Publications by authors named "Sooky Lum"

56 Publications

Associations of the objective built environment along the route to school with children's modes of commuting: A multilevel modelling analysis (the SLIC study).

PLoS One 2020 9;15(4):e0231478. Epub 2020 Apr 9.

Department of Geography, University of Cambridge, Cambridge, England, United Kingdom.

As active commuting levels continue to decline among primary schoolchildren, evidence about which built environmental characteristics influence walking or cycling to school remains inconclusive and is strongly context-dependent. This study aimed to identify the objective built environmental drivers of, and barriers to, active commuting to school for a multi-ethnic sample of 1,889 healthy primary schoolchildren (aged 5-11) in London, UK. Using cross-sectional multilevel ordered logistic regression modelling, supported by the spatial exploration of built environmental characteristics through cartography, the objective built environment was shown to be strongly implicated in children's commuting behaviour. In line with earlier research, proximity to school emerged as the prime variable associated with the choice for active commuting. However, other elements of the urban form were also significantly associated with children's use of active or passive modes of transport. High levels of accidents, crime and air pollution along the route to school were independently correlated with a lower likelihood of children walking or cycling to school. Higher average and minimum walkability and higher average densities of convenience stores along the way were independently linked to higher odds of active commuting. The significance of the relations for crime, air pollution and walkability disappeared in the fully-adjusted model including all built environmental variables. In contrast, relationships with proximity, traffic danger and the food environment were maintained in this comprehensive model. Black children, pupils with obesity, younger participants and those from high socioeconomic families were less likely to actively commute to school. There is thus a particular need to ensure that roads with high volumes of actively commuting children are kept safe and clean, and children's exposure to unhealthy food options along the way is limited. Moreover, as short commuting distances are strongly correlated with walking or cycling, providing high-quality education near residential areas might incite active transport to school.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0231478PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7145202PMC
July 2020

Development and validation of a prediction model for fat mass in children and adolescents: meta-analysis using individual participant data.

BMJ 2019 07 24;366:l4293. Epub 2019 Jul 24.

Population Health Research Institute, St George's, University of London, London SW17 0RE, UK

Objectives: To develop and validate a prediction model for fat mass in children aged 4-15 years using routinely available risk factors of height, weight, and demographic information without the need for more complex forms of assessment.

Design: Individual participant data meta-analysis.

Setting: Four population based cross sectional studies and a fifth study for external validation, United Kingdom.

Participants: A pooled derivation dataset (four studies) of 2375 children and an external validation dataset of 176 children with complete data on anthropometric measurements and deuterium dilution assessments of fat mass.

Main Outcome Measure: Multivariable linear regression analysis, using backwards selection for inclusion of predictor variables and allowing non-linear relations, was used to develop a prediction model for fat-free mass (and subsequently fat mass by subtracting resulting estimates from weight) based on the four studies. Internal validation and then internal-external cross validation were used to examine overfitting and generalisability of the model's predictive performance within the four development studies; external validation followed using the fifth dataset.

Results: Model derivation was based on a multi-ethnic population of 2375 children (47.8% boys, n=1136) aged 4-15 years. The final model containing predictor variables of height, weight, age, sex, and ethnicity had extremely high predictive ability (optimism adjusted R: 94.8%, 95% confidence interval 94.4% to 95.2%) with excellent calibration of observed and predicted values. The internal validation showed minimal overfitting and good model generalisability, with excellent calibration and predictive performance. External validation in 176 children aged 11-12 years showed promising generalisability of the model (R: 90.0%, 95% confidence interval 87.2% to 92.8%) with good calibration of observed and predicted fat mass (slope: 1.02, 95% confidence interval 0.97 to 1.07). The mean difference between observed and predicted fat mass was -1.29 kg (95% confidence interval -1.62 to -0.96 kg).

Conclusion: The developed model accurately predicted levels of fat mass in children aged 4-15 years. The prediction model is based on simple anthropometric measures without the need for more complex forms of assessment and could improve the accuracy of assessments for body fatness in children (compared with those provided by body mass index) for effective surveillance, prevention, and management of clinical and public health obesity.
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http://dx.doi.org/10.1136/bmj.l4293DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6650932PMC
July 2019

Associations of extracurricular physical activity patterns and body composition components in a multi-ethnic population of UK children (the Size and Lung Function in Children study): a multilevel modelling analysis.

BMC Public Health 2019 May 20;19(1):573. Epub 2019 May 20.

Department of Geography, University of Cambridge, Downing Place, Cambridge, CB2 3EN, UK.

Background: Body Mass Index (BMI) is a common outcome when assessing associations between childhood overweight and obesity and physical activity patterns. However, the fat and fat-free components of BMI, measured by the Fat Mass Index (FMI) and Fat-Free Mass Index (FFMI), may show contrasting associations with physical activity, while ethnic groups may vary in both physical activity patterns and body composition. Body composition must therefore be evaluated when assessing the associations between childhood overweight and obesity and physical activity in multi-ethnic populations.

Methods: This cross-sectional study investigated associations of BMI, FMI and FFMI z-scores with extracurricular physical activity for 2171 London primary schoolchildren (aged 5-11 years) of black, South Asian and white/other ethnicity. Multilevel mixed-effects ordered logistic modelling was used, adjusting for age, sex and family and neighbourhood socioeconomic status as potential confounders.

Results: Controlling for ethnicity and individual, family and neighbourhood socioeconomic confounders, actively commuting children had significantly lower Odds Ratios for being in high BMI (Odds Ratio (OR) = 0.678; 95 % Confidence Interval (CI) = 0.531 - 0.865; p - value = 0.002) and FMI z-score groups (OR = 0.679; 95 % CI = 0.499 - 0.922; p = 0.013), but not FFMI z-score groups, than passive commuters. Children doing sports less than once a week had lower Odds Ratios for being in high BMI (OR = 0.435; 95 % CI = 0.236 - 0.802; p = 0.008) and FFMI (OR = 0.455; 95 % CI = 0.214 - 0.969; p = .041) z-score categories compared to daily active children. Differences in FMI between groups did not reach the significance threshold. A trend towards statistical significance was obtained whereby children's complete inactivity was associated with higher odds for being in higher BMI (OR = 2.222 : 95 % CI = 0.977 - 5.052; p = .057) and FMI z-score groups (OR = 2.485 : 95 % CI = 0.961 - 6.429; p = .060). FFMI z-scores did not show a similar trend with complete inactivity.

Conclusions: Active commuting was objectively associated with lower adiposity, while more frequent extracurricular sports participation was correlated with greater fat-free mass accretion. These relationships were independent of ethnicity and individual, family or neighbourhood socioeconomic confounding factors.
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http://dx.doi.org/10.1186/s12889-019-6883-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6526612PMC
May 2019

Preschool Multiple-Breath Washout Testing. An Official American Thoracic Society Technical Statement.

Am J Respir Crit Care Med 2018 03;197(5):e1-e19

Background: Obstructive airway disease is nonuniformly distributed throughout the bronchial tree, although the extent to which this occurs can vary among conditions. The multiple-breath washout (MBW) test offers important insights into pediatric lung disease, not available through spirometry or resistance measurements. The European Respiratory Society/American Thoracic Society inert gas washout consensus statement led to the emergence of validated commercial equipment for the age group 6 years and above; specific recommendations for preschool children were beyond the scope of the document. Subsequently, the focus has shifted to MBW applications within preschool subjects (aged 2-6 yr), where a "window of opportunity" exists for early diagnosis of obstructive lung disease and intervention.

Methods: This preschool-specific technical standards document was developed by an international group of experts, with expertise in both custom-built and commercial MBW equipment. A comprehensive review of published evidence was performed.

Results: Recommendations were devised across areas that place specific age-related demands on MBW systems. Citing evidence where available in the literature, recommendations are made regarding procedures that should be used to achieve robust MBW results in the preschool age range. The present work also highlights the important unanswered questions that need to be addressed in future work.

Conclusions: Consensus recommendations are outlined to direct interested groups of manufacturers, researchers, and clinicians in preschool device design, test performance, and data analysis for the MBW technique.
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http://dx.doi.org/10.1164/rccm.201801-0074STDOI Listing
March 2018

Comparison of facemask and mouthpiece interfaces for multiple breath washout measurements.

J Cyst Fibros 2018 07 2;17(4):511-517. Epub 2018 Mar 2.

Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom; Physiology and Experimental Medicine, Research Institute, Hospital for Sick Children, Toronto, Canada.

Background: Different interfaces (mouthpiece/nose clip vs. facemask) are used during multiple breath washout (MBW) tests in young children.

Methods: We investigated the effect of interface choice and breathing modalities on MBW outcomes in healthy adults and preschool children.

Results: In adults (n = 26) facemask breathing significantly increased LCI, compared to mouthpiece use (mean difference (95% CI) 0.4 (0.2; 0.6)), with results generalizable across sites and different equipment. Exclusively nasal breathing within the facemask increased LCI, as compared to oral breathing. In preschoolers (2-6 years, n = 46), no significant inter-test difference was observed across interfaces for LCI or FRC. Feasibility and breathing stability were significantly greater with facemask (incorporating dead space volume minimization), vs. mouthpiece. This was more pronounced in subjects <4 years of age.

Conclusion: Both nasal vs. oral breathing and mouthpiece vs. facemask affect LCI measurements in adults. This effect was minimal in preschool children, where switching between interfaces is most likely to occur.
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http://dx.doi.org/10.1016/j.jcf.2018.01.003DOI Listing
July 2018

Pulmonary function deficits in newborn screened infants with cystic fibrosis managed with standard UK care are mild and transient.

Eur Respir J 2017 11 9;50(5). Epub 2017 Nov 9.

Clinical Epidemiology, Nutrition and Biostatistics, Population, Policy and Practice Programme, UCL Great Ormond Street Institute of Child Health, London, UK.

With the advent of novel designer molecules for cystic fibrosis (CF) treatment, there is huge need for early-life clinical trial outcomes, such as infant lung function (ILF). We investigated the degree and tracking of ILF abnormality during the first 2 years of life in CF newborn screened infants.Forced expiratory volume in 0.5 s (FEV), lung clearance index (LCI) and plethysmographic functional residual capacity were measured at ∼3 months, 1 year and 2 years in 62 infants with CF and 34 controls.By 2 years there was no significant difference in FEV z-score between CF and controls, whereas mean LCI z-score was 0.81 (95% CI 0.45-1.17) higher in CF. However, there was no significant association between LCI z-score at 2 years with either 3-month or 1-year results. Despite minimal average group changes in any ILF outcome during the second year of life, marked within-subject changes occurred. No child had abnormal LCI or FEV on all test occasions, precluding the ability to identify "high-risk" infants in early life.In conclusion, changes in lung function are mild and transient during the first 2 years of life in newborn screened infants with CF when managed according to a standardised UK treatment protocol. Their potential role in tracking disease to later childhood will be ascertained by ongoing follow-up.
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http://dx.doi.org/10.1183/13993003.00326-2017DOI Listing
November 2017

Longitudinal study of the influence of lung function on vascular health from adolescence to early adulthood in a British multiethnic cohort.

J Hypertens 2017 11;35(11):2185-2191

aDivision of Diabetes and Nutritional Sciences, Cardiovascular Medicine Group, King's College London, London, UK bCentre of Clinical Pharmacy, The Third Xiangya Hospital, Central South University, Changsha, China cRespiratory, Critical Care and Anaesthesia section, University College London Great Ormond Street Institute of Child Health, London, UK dMRC/CSO Social and Public Health Sciences Unit, Institute of Health and Wellbeing, University of Glasgow, Glasgow, Scotland eDepartment Epidemiology and Health, ESRC International Centre for Lifecourse Studies in Society and Health, University College London, London, UK.

Background: Vascular and lung function develop and decline over the life course; both predict cardiovascular events and mortality but little is known of how they develop over time. We analysed their relationship in a multiethnic cohort study to test whether lung function from early adolescence to young adulthood affected vascular indices.

Methods: 'DASH' (http://dash.sphsu.mrc.ac.uk) included 6643 children aged 11-13 years in 2003; a representative 10% sample (n = 665) participated in a pilot follow-up in 2013. Psychosocial, anthropometric, blood pressure (BP), and lung function measures were collected in both surveys; aortic pulse wave velocity (PWV) and augmentation index (AIx) were measured at aged 21-23 years. Relationships between forced expiratory volume Z-scores in 1 s (zFEV1), after global initiative-ethnic adjustments and BP, PWV, and AIx were tested in linear regression and general estimating statistical models.

Results: In total, 488 people with complete data were included. At 11-13 years, SBP was positively associated with zFEV1 (coefficient = 1.90, 95% confidence interval 1.11-2.68, P < 0.001); but not at 21-23 years. The 10-year increase in zFEV1 was associated with rise in SBP (1.38, 0.25-1.51, P < 0.05) in mixed effect models adjusted for age, sex, ethnicity, waist to height ratio, employment, reported racism, smoking, and alcohol use but DBP change was unrelated. In fully adjusted models, neither PWV nor central AIx were associated with zFEV1 at 11-13 years or 21-23 years (P > 0.05).

Conclusion: Forced expiratory volume change is positively and independently associated with SBP change from adolescence to young adulthood, suggesting earlier lung function plays important roles in SBP development. Vascular indices were unrelated to lung function or its change.
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http://dx.doi.org/10.1097/HJH.0000000000001455DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5625963PMC
November 2017

The bronchodilator response in preschool children: A systematic review.

Pediatr Pulmonol 2016 11 6;51(11):1242-1250. Epub 2016 Jun 6.

Respiratory, Critical Care and Anaesthesia Section, University College London Institute of Child Health, 30 Guilford Street, London, WC1N 1EH, United Kingdom.

Background: The bronchodilator response (BDR) is frequently used to support diagnostic and therapeutic decision-making for children who wheeze. However, there is little evidence-based guidance describing the role of BDR testing in preschool children and it is unclear whether published cut-off values, which are derived from adult data, can be applied to this population.

Methods: We searched MEDLINE, EMBASE, Web of Science, and Cochrane databases (inception-September 2015) for studies reporting response to a bronchodilator in healthy preschool children, response following placebo inhalation, and the diagnostic efficacy of BDR compared with a clinical diagnosis of asthma/recurrent wheezing.

Findings: We included 14 studies. Thirteen studies provided BDR data from healthy preschool children. Two studies reported response to placebo in preschool children with asthma/recurrent wheezing. Twelve studies compared BDR measurements from preschool children with asthma/recurrent wheeze to those from healthy children and seven of these studies reported diagnostic efficacy. Significant differences between the BDR measured in healthy preschool children compared with that in children with asthma/recurrent wheeze were demonstrated in some, but not all studies. Techniques such as interrupter resistance, oscillometry, and plethysmography were more consistently successfully completed than spirometry. Between study heterogeneity precluded determination of an optimum technique.

Interpretation: There is little evidence to suggest spirometry-based BDR can be used in the clinical assessment of preschool children who wheeze. Further evaluation of simple alternative techniques is required. Future studies should recruit children in whom airways disease is suspected and should evaluate the ability of BDR testing to predict treatment response. Pediatr Pulmonol. 2016;51:1242-1250. © 2016 Wiley Periodicals, Inc.
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http://dx.doi.org/10.1002/ppul.23459DOI Listing
November 2016

Challenges in Collating Spirometry Reference Data for South-Asian Children: An Observational Study.

PLoS One 2016 27;11(4):e0154336. Epub 2016 Apr 27.

Respiratory, Critical Care & Anaesthesia section (Portex Unit), UCL, Institute of Child Health, London, United Kingdom.

Methods: Spirometry datasets from South-Asian children were collated from four centres in India and five within the UK. Records with transcription errors, missing values for height or spirometry, and implausible values were excluded(n = 110).

Results: Following exclusions, cross-sectional data were available from 8,124 children (56.3% male; 5-17 years). When compared with GLI-predicted values from White Europeans, forced expired volume in 1s (FEV1) and forced vital capacity (FVC) in South-Asian children were on average 15% lower, ranging from 4-19% between centres. By contrast, proportional reductions in FEV1 and FVC within all but two datasets meant that the FEV1/FVC ratio remained independent of ethnicity. The 'GLI-Other' equation fitted data from North India reasonably well while 'GLI-Black' equations provided a better approximation for South-Asian data than the 'GLI-White' equation. However, marked discrepancies in the mean lung function z-scores between centres especially when examined according to socio-economic conditions precluded derivation of a single South-Asian GLI-adjustment.

Conclusion: Until improved and more robust prediction equations can be derived, we recommend the use of 'GLI-Black' equations for interpreting most South-Asian data, although 'GLI-Other' may be more appropriate for North Indian data. Prospective data collection using standardised protocols to explore potential sources of variation due to socio-economic circumstances, secular changes in growth/predictors of lung function and ethnicities within the South-Asian classification are urgently required.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0154336PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4847904PMC
March 2017

Back to school: challenges and rewards of engaging young children in scientific research.

Arch Dis Child 2016 09 26;101(9):785-7. Epub 2016 Apr 26.

Respiratory, Critical Care and Anaesthesia section (Portex Unit), UCL Institute of Child Health, London, UK.

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http://dx.doi.org/10.1136/archdischild-2015-310347DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5013085PMC
September 2016

Natural variability of lung function in young healthy school children.

Eur Respir J 2016 08 13;48(2):411-9. Epub 2016 Apr 13.

Respiratory, Critical Care and Anaesthesia section in Portex Unit, University College London, Institute of Child Health, London, UK.

Knowledge about long-term variability of lung function in healthy children is essential when monitoring and treating those with respiratory disease over time. The aim of this study was to define the natural variability in spirometry in young children after an interval of 12 months.The Size and Lung function In Children study was a prospective study designed to assess spirometry and body size, shape and composition in a multi-ethnic population of London school children. 14 schools with a wide range of socioeconomic circumstances were recruited. Spirometric and anthropometric assessments and parental questionnaires pertaining to respiratory symptoms, previous medical history, pubertal status and socioeconomic circumstances were completed at baseline and ∼1 year later.Technically acceptable spirometry data on two occasions ∼1 year apart (range 9-16 months) were available in 758 children (39% boys, mean±sd age 8.1±1.6 years), 593 of whom were classified as "healthy". Mean±sd within-subject between-test variability was 0.05±0.6 z-scores, with 95% of all the children achieving a between-test variability within ±1.2 z-scores (equating to ∼13% predicted).Natural variations of up to 1.2 z-scores occur in healthy children over ∼1 year. These must be considered when interpreting results from annual reviews in those with lung disease who are otherwise stable, if unnecessary further investigations or changes in treatment are to be avoided.
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http://dx.doi.org/10.1183/13993003.01795-2015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4950968PMC
August 2016

Inclusion of children with airway disease for the development of spirometry reference data.

Eur Respir J 2016 Apr;47(4):1292-3

Respiratory, Critical Care and Anaesthesia section (Portex Unit), UCL, Institute of Child Health, London, UK.

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http://dx.doi.org/10.1183/13993003.02028-2015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4834992PMC
April 2016

New reference ranges for interpreting forced expiratory manoeuvres in infants and implications for clinical interpretation: a multicentre collaboration.

Thorax 2016 Mar 2;71(3):276-83. Epub 2015 Nov 2.

Respiratory, Critical Care & Anaesthesia section in IIIP Programme, UCL, Institute of Child Health, London, UK.

Unlabelled: The raised volume rapid thoracoabdominal compression (RVRTC) technique is commonly used to obtain full forced expiratory manoeuvres from infants, but reference equations derived from 'in-house' equipment have been shown to be inappropriate for current commercially available devices.

Aim: To explore the impact of equipment differences on RVRTC outcomes, derive robust equipment-specific RVRTC reference ranges and investigate their potential clinical impact on data interpretation.

Method: RVRTC data from healthy subjects using Jaeger BabyBody or the 'Respiratory Analysis Software Program, RASP' systems were collated from four centres internationally. Data were excluded if gestational age <37 weeks or birth weight <2.5 kg. Reference equations for RVRTC outcomes were constructed using the LMS (lambda-mu-sigma) method, and compared with published equations using data from newborn screened infants with cystic fibrosis (CF).

Results: RVRTC data from 429 healthy infants (50.3% boys; 88% white infants) on 639 occasions aged 4-118 weeks were available. When plotted against length, flows were significantly higher with RASP than Jaeger, requiring construction of separate equipment-specific regression equations. When comparing results derived from the new equations with those from widely used published equations based on different equipments, discrepancies in forced expiratory volumes and flows of up to 2.5 z-scores were observed, the magnitude of which increased with age. According to published equations, 25% of infants with CF fell below the 95% limits of normal for FEV0.5, compared with only 10% when using the new equations.

Conclusions: Use of equipment-specific prediction equations for RVRTC outcomes will enhance interpretation of infant lung function results; particularly during longitudinal follow-up.
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http://dx.doi.org/10.1136/thoraxjnl-2015-207278DOI Listing
March 2016

Lung function in children in relation to ethnicity, physique and socioeconomic factors.

Eur Respir J 2015 Dec 22;46(6):1662-71. Epub 2015 Oct 22.

Respiratory, Critical Care & Anaesthesia Section in IIIP Programme, UCL Institute of Child Health, London, UK.

Can ethnic differences in spirometry be attributed to differences in physique and socioeconomic factors?Assessments were undertaken in 2171 London primary schoolchildren on two occasions 1 year apart, whenever possible, as part of the Size and Lung function In Children (SLIC) study. Measurements included spirometry, detailed anthropometry, three-dimensional photonic scanning for regional body shape, body composition, information on ethnic ancestry, birth and respiratory history, socioeconomic circumstances, and tobacco smoke exposure.Technically acceptable spirometry was obtained from 1901 children (mean (range) age 8.3 (5.2-11.8) years, 46% boys, 35% White, 29% Black-African origin, 24% South-Asian, 12% Other/mixed) on 2767 test occasions. After adjusting for sex, age and height, forced expiratory volume in 1 s was 1.32, 0.89 and 0.51 z-score units lower in Black-African origin, South-Asian and Other/mixed ethnicity children, respectively, when compared with White children, with similar decrements for forced vital capacity (p<0.001 for all). Although further adjustment for sitting height and chest width reduced differences attributable to ethnicity by up to 16%, significant differences persisted after adjusting for all potential determinants, including socioeconomic circumstances.Ethnic differences in spirometric lung function persist despite adjusting for a wide range of potential determinants, including body physique and socioeconomic circumstances, emphasising the need to use ethnic-specific equations when interpreting results.
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http://dx.doi.org/10.1183/13993003.00415-2015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4668600PMC
December 2015

Acceptability, Precision and Accuracy of 3D Photonic Scanning for Measurement of Body Shape in a Multi-Ethnic Sample of Children Aged 5-11 Years: The SLIC Study.

PLoS One 2015 28;10(4):e0124193. Epub 2015 Apr 28.

Respiratory, Critical Care and Anaesthesia section (Portex Unit), UCL Institute of Child Health, London, United Kingdom.

Background: Information on body size and shape is used to interpret many aspects of physiology, including nutritional status, cardio-metabolic risk and lung function. Such data have traditionally been obtained through manual anthropometry, which becomes time-consuming when many measurements are required. 3D photonic scanning (3D-PS) of body surface topography represents an alternative digital technique, previously applied successfully in large studies of adults. The acceptability, precision and accuracy of 3D-PS in young children have not been assessed.

Methods: We attempted to obtain data on girth, width and depth of the chest and waist, and girth of the knee and calf, manually and by 3D-PS in a multi-ethnic sample of 1484 children aged 5-11 years. The rate of 3D-PS success, and reasons for failure, were documented. Precision and accuracy of 3D-PS were assessed relative to manual measurements using the methods of Bland and Altman.

Results: Manual measurements were successful in all cases. Although 97.4% of children agreed to undergo 3D-PS, successful scans were only obtained in 70.7% of these. Unsuccessful scans were primarily due to body movement, or inability of the software to extract shape outputs. The odds of scan failure, and the underlying reason, differed by age, size and ethnicity. 3D-PS measurements tended to be greater than those obtained manually (p < 0.05), however ranking consistency was high (r2 > 0.90 for most outcomes).

Conclusions: 3D-PS is acceptable in children aged ≥ 5 years, though with current hardware/software, and body movement artefacts, approximately one third of scans may be unsuccessful. The technique had poorer technical success than manual measurements, and had poorer precision when the measurements were viable. Compared to manual measurements, 3D-PS showed modest average biases but acceptable limits of agreement for large surveys, and little evidence that bias varied substantially with size. Most of the issues we identified could be addressed through further technological development.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0124193PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4412635PMC
April 2016

How "healthy" should children be when selecting reference samples for spirometry?

Eur Respir J 2015 Jun 19;45(6):1576-81. Epub 2015 Feb 19.

Respiratory, Critical Care and Anaesthesia section (Portex Unit), University College London, Institute of Child Health, London, UK.

How "healthy" do children need to be when selecting reference samples for spirometry? Anthropometry and spirometry were measured in an unselected, multi-ethnic population of school children aged 5-11 years in London, UK, with follow-up assessments 12 months later. Parents provided information on children's birth data and health status. Forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) were adjusted for sex, age, height and ethnicity using the 2012 Global Lungs Initiative equations, and the effects of potential exclusion criteria on the z-score distributions were examined. After exclusions for current and chronic lung disease, acceptable data were available for 1901 children on 2767 occasions. Healthy children were defined as those without prior asthma or hospitalisation for respiratory problems, who were born at full-term with a birthweight ≥2.5 kg and who were asymptomatic at testing. Mean±sd z-scores for FEV1 and FVC approximated 0±1, indicating the 2012 Global Lungs Initiative equations were appropriate for this healthy population. However, if children born preterm or with low birthweight, children with prior asthma or children mildly symptomatic at testing were included in the reference, overall results were similar to those for healthy children, while increasing the sample size by 25%. With the exception of clear-cut factors, such as current and chronic respiratory disease, paediatric reference samples for spirometry can be relatively inclusive and hence more generalisable to the target population.
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http://dx.doi.org/10.1183/09031936.00223814DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4452263PMC
June 2015

Birth data accessibility via primary care health records to classify health status in a multi-ethnic population of children: an observational study.

NPJ Prim Care Respir Med 2015 Jan 22;25:14112. Epub 2015 Jan 22.

Respiratory, Critical Care & Anaesthesia Section (Portex Unit), UCL, Institute of Child Health, London, UK.

Background: Access to reliable birth data (birthweight (BW) and gestational age (GA)) is essential for the identification of individuals who are at subsequent health risk.

Aims: This study aimed to explore the feasibility of retrospectively collecting birth data for schoolchildren from parental questionnaires (PQ) and general practitioners (GPs) in primary care clinics, in inner city neighbourhoods with high density of ethnic minority and disadvantaged populations.

Methods: Attempts were made to obtain birth data from parents and GPs for 2,171 London primary schoolchildren (34% White, 29% Black African origin, 25% South Asians, 12% Other) as part of a larger study of respiratory health.

Results: Information on BW and/or GA were obtained from parents for 2,052 (95%) children. Almost all parents (2,045) gave consent to access their children's health records held by GPs. On the basis of parental information, GPs of 1,785 children were successfully contacted, and GPs of 1,202 children responded. Birth data were retrieved for only 482 children (22% of 2,052). Missing birth data from GPs were associated with non-white ethnicity, non-UK born, English not the dominant language at home or socioeconomic disadvantage. Paired data were available in 376 children for BW and in 407 children for GA. No significant difference in BW or GA was observed between PQ and GP data, with <5% difference between sources regardless of normal or low birth weight, or term or preterm status.

Conclusions: Parental recall of birth data for primary schoolchildren yields high quality and rapid return of data, and it should be considered as a viable alternative in which there is limited access to birth records. It provides the potential to include children with an increased risk of health problems within epidemiological studies.
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http://dx.doi.org/10.1038/npjpcrm.2014.112DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4353844PMC
January 2015

Ethnic variability in body size, proportions and composition in children aged 5 to 11 years: is ethnic-specific calibration of bioelectrical impedance required?

PLoS One 2014 5;9(12):e113883. Epub 2014 Dec 5.

Childhood Nutrition Research Centre, UCL Institute of Child Health, London, United Kingdom.

Background: Bioelectrical Impedance Analysis (BIA) has the potential to be used widely as a method of assessing body fatness and composition, both in clinical and community settings. BIA provides bioelectrical properties, such as whole-body impedance which ideally needs to be calibrated against a gold-standard method in order to provide accurate estimates of fat-free mass. UK studies in older children and adolescents have shown that, when used in multi-ethnic populations, calibration equations need to include ethnic-specific terms, but whether this holds true for younger children remains to be elucidated. The aims of this study were to examine ethnic differences in body size, proportions and composition in children aged 5 to 11 years, and to establish the extent to which such differences could influence BIA calibration.

Methods: In a multi-ethnic population of 2171 London primary school-children (47% boys; 34% White, 29% Black African/Caribbean, 25% South Asian, 12% Other) detailed anthropometric measurements were performed and ethnic differences in body size and proportion were assessed. Ethnic differences in fat-free mass, derived by deuterium dilution, were further evaluated in a subsample of the population (n = 698). Multiple linear regression models were used to calibrate BIA against deuterium dilution.

Results: In children < 11 years of age, Black African/Caribbean children were significantly taller, heavier and had larger body size than children of other ethnicities. They also had larger waist and limb girths and relatively longer legs. Despite these differences, ethnic-specific terms did not contribute significantly to the BIA calibration equation (Fat-free mass = 1.12+0.71*(height2/impedance)+0.18*weight).

Conclusion: Although clear ethnic differences in body size, proportions and composition were evident in this population of young children aged 5 to 11 years, an ethnic-specific BIA calibration equation was not required.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0113883PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4257615PMC
July 2015

Disparities in pulmonary function in healthy children across the Indian urban-rural continuum.

Am J Respir Crit Care Med 2015 Jan;191(1):79-86

1 Respiratory, Critical Care, and Anaesthesia Section (Portex Unit) and.

Rationale: Marked socioeconomic health-care disparities are recognized in India, but lung health inequalities between urban and rural children have not been studied.

Objectives: We investigated whether differences exist in spirometric pulmonary function in healthy children across the Indian urban-rural continuum and compared results with those from Indian children living in the UK.

Methods: Indian children aged 5 to 12 years were recruited from Indian urban, semiurban, and rural schools, and as part of the Size and Lung Function in Children study, London. Anthropometric and spirometric assessments were undertaken.

Measurements And Main Results: Acceptable spirometric data were obtained from 728 (58% boys) children in India and 311 (50% boys) UK-Indian children. As an entire group, the India-resident children had significantly lower z FEV1 and z FVC than UK-Indian children (P < 0.0005), when expressed using Global Lung Function Initiative-2012 equations. However, when India-resident children were categorized according to residence, there were no differences in z FEV1 and z FVC between Indian-urban and UK-Indian children. There were, however, significant reductions of ∼ 0.5 z scores and 0.9 z scores in both FEV1 and FVC (with no difference in FEV1/FVC) in Indian-semiurban and Indian-rural children, respectively, when compared with Indian-urban children (P < 0.0005). z Body mass index, socioeconomic circumstances, tobacco, and biomass exposure were individually significantly associated with z FEV1 and z FVC (P < 0.0005).

Conclusions: The presence of an urban-rural continuum of lung function within a specific ethnic group emphasizes the impact of environmental factors on lung growth in emerging nations such as India, which must be taken into account when developing ethnic-specific reference values or designing studies to optimize lung health.
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http://dx.doi.org/10.1164/rccm.201406-1049OCDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4299630PMC
January 2015

Assessing pubertal status in multi-ethnic primary schoolchildren.

Acta Paediatr 2015 Jan 17;104(1):e45-8. Epub 2014 Nov 17.

Respiratory, Critical Care & Anaesthesia Section (Portex Unit), UCL Institute of Child Health, London, UK.

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http://dx.doi.org/10.1111/apa.12850DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4463762PMC
January 2015

Lung function testing in children: importance of race and ethnic-specific reference equations.

Expert Rev Respir Med 2014 Oct 26;8(5):527-31. Epub 2014 Jun 26.

Respiratory, Critical Care and Anaesthesia Section (Portex Unit), UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK.

Marked differences in lung function occur between children of different racial and ethnic backgrounds even when all known confounders including socioeconomic circumstances have been taken into account. Use of ethnic-specific equations, such as those recently published by the Global Lung Function Initiative, help to minimize such differences, thereby improving the accuracy with which lung disease can be identified and treated during childhood, as well as enabling the true impact of adverse environmental or socioeconomic exposures to be assessed, irrespective of ethnic background. In future, incorporation of ancestry and, within emerging nations undergoing secular changes in anthropometry, sitting height, into normative equations may further improve the accuracy of predicting lung function and hence assessment of disease severity within any given individual.
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http://dx.doi.org/10.1586/17476348.2014.927317DOI Listing
October 2014

How to avoid misinterpreting lung function tests in children: a few practical tips.

Paediatr Respir Rev 2014 Jun 13;15(2):170-80. Epub 2014 Feb 13.

Portex Respiratory Unit, UCL, Institute of Child Health, London, UK.

Assessments of pulmonary function play an integral part in the clinical management of school age children as well as providing objective outcome measures in clinical and epidemiological research studies. Pulmonary function tests (PFTs) can also be undertaken in sleeping infants and in awake young children from 3 years of age. However, the clinical utility of such assessments, which are generally confined to specialist centres, has yet to be established. Whether requesting or undertaking paediatric PFTs, or simply reading about how these tests have been applied in research studies, it is essential to question whether results have been interpreted in a meaningful way. This review summarises some of the issues that need to be considered, including: why the tests are being performed; which tests are most likely to detect the suspected pathophysiology; how often such tests should be repeated; whether results are likely to be reliable (in terms of data quality, repeatability and the availability of suitable reference equations with which to distinguish the effects of disease from those of growth and development), and whether the selected tests are likely to be feasible in the individual child or study group under investigation.
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http://dx.doi.org/10.1016/j.prrv.2014.02.001DOI Listing
June 2014

Impact of ethnicity and extreme prematurity on infant pulmonary function.

Pediatr Pulmonol 2014 Jul 30;49(7):679-87. Epub 2013 Sep 30.

Portex Respiratory Unit, UCL Institute of Child Health, London, WC1N 1EH, UK; Paediatric Respiratory Medicine Unit, Great Ormond Street Hospital for Children NHS Foundation Trust, London, WC1N 3JH, UK.

The impact of birth before 27 completed weeks of gestation on infant pulmonary function (PF) was explored in a multi-ethnic population in comparison to more mature preterm controls (PTC) and healthy fullterm infants. Plethysmographic lung volume (FRCpleth ) and forced expired volume (FEV0.5 ) were obtained at ∼12 months post-term age in 52 extremely preterm (EP) infants (median [range] gestational age [GA]: 26 [23-27] weeks; 40% White mothers; 79% with BPD), 41 PTC (GA:35 [30-36] weeks; 37% White mothers) and 95 fullterm infants (GA:40 [37-42] weeks; 86% White mothers). Using reference equations based on identical equipment and techniques, results were expressed as z-scores to adjust for age, sex and body size. FEV0.5 was significantly lower in EP infants when compared with PTC (mean difference [95% CI]: -1.02[-1.60; -0.44] z-scores, P < 0.001), as was forced vital capacity (FVC) but there were no significant differences in FRCpleth or FEV0.5 /FVC ratio. FEV0.5 , FVC, and FEV0.5 /FVC were significantly lower in both preterm groups when compared with fullterm controls. On multivariable analyses of the combined preterm dataset: FEV0.5 at ∼1 year was 0.11 [0.05; 0.17] z-scores higher/week GA, and 1.28 (0.49; 2.08) z-scores lower in EP infants with prior BPD. Among non-white preterm infants, FEV0.5 was 0.70 (0.17; 1.24) z-scores lower, with similar reductions in FVC, such that there were no ethnic differences in FEV0.5 /FVC. Similar ethnic differences were observed among fullterm infants. These results confirm the negative impact of preterm birth on subsequent lung development, especially following a diagnosis of BPD, and emphasize the importance of taking ethnic background into account when interpreting results during infancy as in older subjects.
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http://dx.doi.org/10.1002/ppul.22882DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4285893PMC
July 2014

Evolution of lung function during the first year of life in newborn screened cystic fibrosis infants.

Thorax 2014 Oct 26;69(10):910-7. Epub 2013 Sep 26.

Portex Unit: Respiratory Physiology and Medicine, UCL Institute of Child Health, London, UK.

Rationale: Newborn screening (NBS) for cystic fibrosis (CF) allows early intervention. Design of randomised controlled trials (RCT) is currently impeded by uncertainty regarding evolution of lung function, an important trial end point in such infants.

Objective: To assess changes in pulmonary function during the first year of life in CF NBS infants.

Methods: Observational longitudinal study. CF NBS infants and healthy controls were recruited between 2009 and 2011. Lung Clearance Index (LCI), plethysmographic lung volume (plethysmographic functional residual capacity (FRCpleth)) and forced expired volume (FEV₀.₅) were measured at 3 months and 1 year of age.

Main Results: Paired measurements were obtained from 72 CF infants and 44 controls. At 3 months, CF infants had significantly worse lung function for all tests. FEV₀.₅ improved significantly (0.59 (95% CI 0.18 to 0.99) z-scores; p<0.01) in CF infants between 3 months and 1 year, and by 1 year, FEV₀.₅ was only 0.52 (0.89 to 0.15) z-scores less than in controls. LCI and FRCpleth remained stable throughout the first year of life, being on average 0.8 z-scores higher in infants with CF. Pulmonary function at 1 year was predicted by that at 3 months. Among the 45 CF infants with entirely normal LCI and FEV₀.₅ at 3 months, 80% remained so at 1 year, while 74% of those with early abnormalities remained abnormal at 1 year.

Conclusions: This is the first study reporting improvements in FEV₀.₅ over time in stable NBS CF infants treated with standard therapy. Milder changes in lung function occurred by 1 year than previously reported. Lung function at 3 months predicts a high-risk group, who should be considered for intensification of treatment and enrolment into RCTs.
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http://dx.doi.org/10.1136/thoraxjnl-2013-204023DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4174068PMC
October 2014

An official American Thoracic Society workshop report: optimal lung function tests for monitoring cystic fibrosis, bronchopulmonary dysplasia, and recurrent wheezing in children less than 6 years of age.

Ann Am Thorac Soc 2013 Apr;10(2):S1-S11

Although pulmonary function testing plays a key role in the diagnosis and management of chronic pulmonary conditions in children under 6 years of age, objective physiologic assessment is limited in the clinical care of infants and children less than 6 years old, due to the challenges of measuring lung function in this age range. Ongoing research in lung function testing in infants, toddlers, and preschoolers has resulted in techniques that show promise as safe, feasible, and potentially clinically useful tests. Official American Thoracic Society workshops were convened in 2009 and 2010 to review six lung function tests based on a comprehensive review of the literature (infant raised-volume rapid thoracic compression and plethysmography, preschool spirometry, specific airway resistance, forced oscillation, the interrupter technique, and multiple-breath washout). In these proceedings, the current state of the art for each of these tests is reviewed as it applies to the clinical management of infants and children under 6 years of age with cystic fibrosis, bronchopulmonary dysplasia, and recurrent wheeze, using a standardized format that allows easy comparison between the measures. Although insufficient evidence exists to recommend incorporation of these tests into the routine diagnostic evaluation and clinical monitoring of infants and young children with cystic fibrosis, bronchopulmonary dysplasia, or recurrent wheeze, they may be valuable tools with which to address specific concerns, such as ongoing symptoms or monitoring response to treatment, and as outcome measures in clinical research studies.
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http://dx.doi.org/10.1513/AnnalsATS.201301-017STDOI Listing
April 2013

Reference standards for forced expiratory indices in Chinese preschool children.

Pediatr Pulmonol 2013 Nov 8;48(11):1119-26. Epub 2013 Feb 8.

Department of Pediatrics, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong.

Spirometric testing is traditionally achievable in children of school-age and beyond. Incorporation of interactive incentives motivates preschool children to facilitate measurement of forced expiratory indices. Validated spirometric reference standards are available for Caucasian preschoolers but lacking in Asians. We established spirometric references in Chinese children aged 2-7 years, who were recruited from 19 randomly selected nurseries and kindergartens in Hong Kong. Parents completed International Study of Asthma and Allergies in Childhood questionnaire, and children concurrently performed incentive spirometry on-site according to international guideline. Prediction equations for spirometric indices were formulated by linear regression. One thousand four hundred two (72.9%) of 1,922 consented children, with mean (SD) age 4.4 (1.0) years, successfully performed spirometry. Following exclusions due to medical and technical reasons, 895 (63.8%) children contributed spirometric data to our references. Girls had lower FEV0.5 , FEV0.75 , FEV1 , FVC, and PEF but similar FEF25-75 than boys, adjusted for age, weight, and standing height as covariates. Standing height was the most important predictor for FEV0.5 , FEV0.75 , FEV1 , FVC, and PEF in both boys (adjusted R(2) 0.525-0.734) and girls (adjusted R(2) 0.583-0.721), whereas the best prediction model for both gender is formed by standing height, weight, and age. At various standing heights, our preschoolers had FEV1 Z-scores 0.13-1.00 higher than those of collaborative Caucasian reference. This study justifies the need for ethnic-specific reference equations and presents spirometry references in young Chinese children. Their forced expiratory indices are determined by gender, age, weight and standing height, and standing height is the best anthropometric index to predict all spirometric indices.
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http://dx.doi.org/10.1002/ppul.22773DOI Listing
November 2013

Consensus statement for inert gas washout measurement using multiple- and single- breath tests.

Eur Respir J 2013 Mar 8;41(3):507-22. Epub 2013 Feb 8.

Dept of Respiratory Medicine, The Children’s Hospital at Westmead, Westmead, Sydney, Australia.

Inert gas washout tests, performed using the single- or multiple-breath washout technique, were first described over 60 years ago. As measures of ventilation distribution inhomogeneity, they offer complementary information to standard lung function tests, such as spirometry, as well as improved feasibility across wider age ranges and improved sensitivity in the detection of early lung damage. These benefits have led to a resurgence of interest in these techniques from manufacturers, clinicians and researchers, yet detailed guidelines for washout equipment specifications, test performance and analysis are lacking. This manuscript provides recommendations about these aspects, applicable to both the paediatric and adult testing environment, whilst outlining the important principles that are essential for the reader to understand. These recommendations are evidence based, where possible, but in many places represent expert opinion from a working group with a large collective experience in the techniques discussed. Finally, the important issues that remain unanswered are highlighted. By addressing these important issues and directing future research, the hope is to facilitate the incorporation of these promising tests into routine clinical practice.
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http://dx.doi.org/10.1183/09031936.00069712DOI Listing
March 2013

Age and height dependence of lung clearance index and functional residual capacity.

Eur Respir J 2013 Jun 8;41(6):1371-7. Epub 2012 Nov 8.

Portex Respiratory Unit, UCL Institute of Child Health, London, UK.

The lung clearance index (LCI) is more sensitive than spirometry in detecting abnormal lung function in children with cystic fibrosis. LCI is thought to be independent of age, but recent evidence suggests that the upper limit of normal is higher in infants and preschool children than in older subjects. This study examines whether LCI remains independent of body size throughout childhood. Multiple-breath washout data from healthy children and adolescents were collated from three centres using the mass spectrometer system and the inert gas sulfur hexafluoride. Reference equations for LCI and functional residual capacity (FRC) were constructed using the LMS (lambda-mu-sigma) method. Data were available from 497 subjects (2 weeks to 19 years of age) tested on 659 occasions. LCI was dependent on body size, decreasing in a nonlinear pattern as height increased. Changes were particularly marked in the first 5 years of life. Height, age and sex were all independent predictors of FRC. Minimal between-centre differences allowed unified reference equations to be developed. LCI is not independent of body size. Although a constant upper normal limit would suffice for cross-sectional clinical assessments from 6 years of age, appropriate reference equations are essential for accurate interpretation of results during early childhood.
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http://dx.doi.org/10.1183/09031936.00005512DOI Listing
June 2013