Publications by authors named "Jamie M Madden"

12 Publications

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Protective immunity against tuberculosis in a free-living badger population vaccinated orally with Mycobacterium bovis Bacille Calmette-Guérin.

Transbound Emerg Dis 2021 Jul 31. Epub 2021 Jul 31.

Tuberculosis Diagnostics and Immunology Research Laboratory, School of Veterinary Medicine, University College Dublin (UCD), Dublin, Ireland.

Vaccination of badgers with Mycobacterium bovis Bacille Calmette-Guérin (BCG) has been shown to protect badgers against tuberculosis in experimental trials. During the 3-year County Kilkenny BCG vaccine field study, badgers were treated orally with placebo (100% in Zone A), BCG (100% in Zone C) or randomly assigned 50%: 50% treatment with BCG or placebo (Zone B). At the end of the study, 275 badgers were removed from the trial area and subjected to detailed post-mortem examination followed by histology and culture for M. bovis. Among these badgers, 83 (30.2%) were captured for the first time across the three zones, representing a non-treated proportion of the population. Analysis of the data based on the infection status of treated animals showed a prevalence of 52% (95% CI: 40%-63%) infection in Zone A (placebo), 39% (95% CI: 17%-64%) in Zone B (placebo) and 44% (95% CI: 20%-70%) in Zone B (BCG vaccinated) and 24% (95% CI: 14%-36%) in Zone C (BCG vaccinated). There were no statistically significant differences in the proportion of animals with infection involving the lung and thoracic lymph nodes, extra-thoracic infection or in the distribution and severity scores of histological lesions. Among the 83 non-treated badgers removed at the end of the study, the infection prevalence of animals in Zone A (prevalence = 46%, 95% CI: 32%-61%) and Zone B (prevalence = 44%, 95% CI: 23%-67%) was similar to the treated animals in these zones. However, in Zone C, no evidence of infection was found in any of the untreated badgers (prevalence = 0%, 95% CI: 0%-14%). This is consistent with an indirect protective effect in the non-vaccinated badgers leading to a high level of population immunity. The results suggest that BCG vaccination of badgers could be a highly effective means of reducing the incidence of tuberculosis in badger populations.
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http://dx.doi.org/10.1111/tbed.14254DOI Listing
July 2021

Population Mobility Trends, Deprivation Index and the Spatio-Temporal Spread of Coronavirus Disease 2019 in Ireland.

Int J Environ Res Public Health 2021 06 10;18(12). Epub 2021 Jun 10.

Centre for Veterinary Epidemiology and Risk Analysis (CVERA), School of Veterinary Medicine, University College Dublin, D04 W6F6 Dublin, Ireland.

Like most countries worldwide, the coronavirus disease (COVID-19) has adversely affected Ireland. The aim of this study was to (i) investigate the spatio-temporal trend of COVID-19 incidence; (ii) describe mobility trends as measured by aggregated mobile phone records; and (iii) investigate the association between deprivation index, population density and COVID-19 cases while accounting for spatial and temporal correlation. Standardised incidence ratios of cases were calculated and mapped at a high spatial resolution (electoral division level) over time. Trends in the percentage change in mobility compared to a pre-COVID-19 period were plotted to investigate the impact of lockdown restrictions. We implemented a hierarchical Bayesian spatio-temporal model (Besag, York and Mollié (BYM)), commonly used for disease mapping, to investigate the association between covariates and the number of cases. There have been three distinct "waves" of COVID-19 cases in Ireland to date. Lockdown restrictions led to a substantial reduction in human movement, particularly during the 1st and 3rd wave. Despite adjustment for population density (incidence ratio (IR) = 1.985 (1.915-2.058)) and the average number of persons per room (IR = 10.411 (5.264-22.533)), we found an association between deprivation index and COVID-19 incidence (IR = 1.210 (CI: 1.077-1.357) for the most deprived quintile compared to the least deprived). There is a large range of spatial heterogeneity in COVID-19 cases in Ireland. The methods presented can be used to explore locally intensive surveillance with the possibility of localised lockdown measures to curb the transmission of infection, while keeping other, low-incidence areas open. Our results suggest that prioritising densely populated deprived areas (that are at increased risk of comorbidities) during vaccination rollout may capture people that are at risk of infection and, potentially, also those at increased risk of hospitalisation.
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http://dx.doi.org/10.3390/ijerph18126285DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8296107PMC
June 2021

Future Risk of Bovine Tuberculosis () Breakdown in Cattle Herds 2013-2018: A Dominance Analysis Approach.

Microorganisms 2021 May 6;9(5). Epub 2021 May 6.

Ruminant Animal Health Division, Department of Agriculture, Food and the Marine, Backweston Co., W23 X3PH Kildare, Ireland.

Bovine tuberculosis (bTB) remains a significant endemic pathogen of cattle herds, despite multi-decadal control programmes being in place in several countries. Understanding the risks of future bTB breakdown (BD) and the associated characteristics of herds and index breakdowns could help inform risk categorisation. Such risk categories could then contribute to tailored management and policies. Here, we estimated the future risk of herd BD for the cohort of herds that were derestricted during 2013 in Ireland using multivariable logit regression models, with a dominance analysis approach. One third of herds that were derestricted in 2013 experienced a breakdown during the follow-up five year period (1469/4459; 33%). BD length was a significant predictor of future risk, primarily driven by long BDs > 230 days relative to short BDs < 130 days (OR 95%CI: 1.157-1.851), as was having had a previous BD (OR 95%CI: 1.012-1.366). Herd-size was the dominant predictor of future risk (accounted for 46% of predicted variance), suggesting significant increase in risk of future breakdown with increasing (log) herd-size (OR 95%CI: 1.378-1.609). There was significant spatial variation in future risk across counties, and it was the second most dominant predictor of future risk (25% of predicted variance). The size of index breakdowns was not a strong predictor of future risk over a 5-year period. These findings can inform a risk-based policy development.
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http://dx.doi.org/10.3390/microorganisms9051004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8148532PMC
May 2021

Bovine Tuberculosis () Outbreak Duration in Cattle Herds in Ireland: A Retrospective Observational Study.

Pathogens 2020 Oct 5;9(10). Epub 2020 Oct 5.

Ruminant Animal Health Division, Department of Agriculture, Food and the Marine, Backweston, W23 VW2C Co. Kildare, Ireland.

Bovine tuberculosis (bTB) outbreaks, caused by infection, are a costly animal health challenge. Understanding factors associated with the duration of outbreaks, known as breakdowns, could lead to better disease management policy development. We undertook a retrospective observational study (2012-2018) and employed Finite Mixture Models (FMM) to model the outcome parameter, and to investigate how factors were associated with duration for differing subpopulations identified. In addition to traditional risk factors (e.g., herd size, bTB history), we also explored farm geographic area, parcels/farm fragmentation, metrics of intensity via nitrogen loading, and whether herds were designated controlled beef finishing units (CBFU) as potential risk factors for increased duration. The final model fitted log-normal distributions, with two latent classes (k) which partitioned the population into a subpopulation around the central tendency of the distribution, and a second around the tails of the distribution. The latter subpopulation included longer breakdowns of policy interest. Increasing duration was positively associated with recent (<3 years) TB history and the number of reactors disclosed, (log) herd size, beef herd-type relative to other herd types, number of land parcels, area, being designated a CBFU ("feedlot") and having high annual inward cattle movements within the "tails" subpopulation. Breakdown length was negatively associated with the year of commencement of breakdown (i.e., a decreasing trend) and non-significantly with the organic nitrogen produced on the farm (N kg/hectare), a measure of stocking density. The latter finding may be due to confounding effects with herd size and area. Most variables contributed only moderately to explaining variation in breakdown duration, that is, they had moderate size effects on duration. Herd-size and CBFU had greater effect sizes on the outcome. The findings contribute to evidence-based policy formation in Ireland.
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http://dx.doi.org/10.3390/pathogens9100815DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7650827PMC
October 2020

Spatial and network characteristics of Irish cattle movements.

Prev Vet Med 2020 Oct 17;183:105095. Epub 2020 Aug 17.

UCD Centre for Veterinary Epidemiology and Risk Analysis, UCD School of Veterinary Medicine, University College Dublin, Ireland.

Our aim was to examine, for the first time, the spatial and network characteristics of cattle movements between herds in the Republic of Ireland (ROI), to inform policy and research of relevance to the surveillance and management of disease in Irish cattle. We analysed movements in 2016 as discrete herd to herd pairings (degree), herd to herd pairings by date of move (contacts) and herd to herd pairings by date and individual animal (transfers), and looked at each of these as movements out of a herd (out degree, out contacts, out transfers) and into a herd (in degree, in contacts, in transfers). We found that the frequency distributions, by herd, of these six move types were all heavily right skewed but in the case of the 'out' data types more closely followed a log-normal than the scale free distribution often reported for livestock movement data. For each distinct herd to herd contact in a given direction, over 90 % occurred only once, whereas the maximum number of occurrences was 62. Herd-level Spearman rank correlations between inward moves (represented as in degree, in contacts, in transfers) and outward moves (out degree, out contacts, out transfers) were weak or even negative whereas correlations between different measures of outward moves or inward moves (e.g. out degree vs. out contacts, in transfers vs. in degree) were stronger. Correlations between these variables and the network measure betweenness varied between r = 0.513 and r = 0.587. Some herds took part in a relatively large number of movements whilst also retaining their cattle for long periods (> 100 days) between moves. In and out degree, contacts and transfers were mapped across Ireland on a 5 km grid, and additionally normalized per 1000 animals and per herd. We found considerable variation in the number of movements by county. Approximately half of transfers were conducted within a single county, but the number and distance of between county movements varied considerably by county of origin and county of destination, with the proportion of moves completed within a single county correlated with its size. Herds exchanging cattle via a market were generally further apart than when moves were made directly herd to herd. For contacts, the distances moved away from the herd were on average greater for origin herds in the west of ROI whereas distances moved to a herd were generally greater for destination herds in the centre-east and the north-west.
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http://dx.doi.org/10.1016/j.prevetmed.2020.105095DOI Listing
October 2020

Post-mortem surveillance of bovine tuberculosis in Ireland: herd-level variation in the probability of herds disclosed with lesions at routine slaughter to have skin test reactors at follow-up test.

Vet Res Commun 2020 Nov 24;44(3-4):131-136. Epub 2020 Jun 24.

Ruminant Animal Health Division, Department of Agriculture, Food and the Marine, Backweston, Co. Dublin, Ireland.

Post-mortem surveillance in Ireland discloses skin-test negative cattle with presumptive evidence of infection of Mycobacterium bovis (lesions at routine slaughter (LRS)), the causative agent of bovine tuberculosis (bTB). Laboratory confirmation of lesions has impacts on trade restrictions for herds, therefore if laboratory capacity was diminished, how herds are treated would require an informed risk policy. Here we report the proportion of herds with subsequent evidence of within-herd transmission, based on skin-test results. We assess how herd-size, herd-type, and bTB-history affect the probability of additional reactors at follow-up test using univariable and multivariable random-effects models. The study represents a rapid response to developing an evidential base for policy demands during an extraordinary event, the COVID-19 epidemic in Ireland. A dataset from 2005 to 2019 of breakdowns were collated. Overall, 20,116 breakdowns were initiated by LRS cases. During the index tests of these breakdowns, 3931 revealed ≥1 skin-test reactor animals (19.54%; ≥1 standard reactors: 3827; 19.02%). Increasing herd-size was associated with reactor disclosure on follow-up. For small herds (<33 animals), 11.74% of follow-up tests disclosed ≥1 reactor; 24.63% of follow-up tests from very large herds (>137) disclosed ≥1 reactors. Beef (13.87%) and "other" (13%) herd production types had lower proportion of index tests with reactors in comparison with dairy (28.27%) or suckler (20.48%) herds. Historic breakdown size during the previous 3-years was associated reactor disclosure risk on follow-up. Our results are useful for rapid tailored policy development aimed at identifying higher risk herds.
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http://dx.doi.org/10.1007/s11259-020-09777-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7312117PMC
November 2020

Fitting Marginal Structural and G-Estimation Models Under Complex Treatment Patterns: Investigating the Association Between De Novo Vitamin D Supplement Use After Breast Cancer Diagnosis and All-Cause Mortality Using Linked Pharmacy Claim and Registry Data.

Am J Epidemiol 2020 03;189(3):224-234

Studies have shown that accounting for time-varying confounding through time-dependent Cox proportional hazards models may provide biased estimates of the causal effect of treatment when the confounder is also a mediator. We explore 2 alternative approaches to addressing this problem while examining the association between vitamin D supplementation initiated after breast cancer diagnosis and all-cause mortality. Women aged 50-80 years were identified in the National Cancer Registry Ireland (n = 5,417) between 2001 and 2011. Vitamin D use was identified from linked prescription data (n = 2,570). We sought to account for the time-varying nature of vitamin D use and time-varying confounding by bisphosphonate use using 1) marginal structural models (MSMs) and 2) G-estimation of structural nested accelerated failure-time models (SNAFTMs). Using standard adjusted Cox proportional hazards models, we found a reduction in all-cause mortality in de novo vitamin D users compared with nonusers (hazard ratio (HR) = 0.84, 95% confidence interval (CI): 0.73, 0.99). Additional adjustment for vitamin D and bisphosphonate use in the previous month reduced the hazard ratio (HR = 0.45, 95% CI: 0.33, 0.63). Results derived from MSMs (HR = 0.44, 95% CI: 0.32, 0.61) and SNAFTMs (HR = 0.45, 95% CI: 0.34, 0.52) were similar. Utilizing MSMs and SNAFTMs to account for time-varying bisphosphonate use did not alter conclusions in this example.
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http://dx.doi.org/10.1093/aje/kwz243DOI Listing
March 2020

Exploring diurnal variation using piecewise linear splines: an example using blood pressure.

Emerg Themes Epidemiol 2017 2;14. Epub 2017 Feb 2.

Department of Epidemiology and Public Health, University College Cork, Cork, Ireland.

Background: There are many examples of physiological processes that follow a circadian cycle and researchers are interested in alternative methods to illustrate and quantify this diurnal variation. Circadian blood pressure (BP) deserves additional attention given uncertainty relating to the prognostic significance of BP variability in relation to cardiovascular disease. However, the majority of studies exploring variability in ambulatory blood pressure monitoring (ABPM) collapse the data into single readings ignoring the temporal nature of the data. Advanced statistical techniques are required to explore complete variation over 24 h.

Methods: We use piecewise linear splines in a mixed-effects model with a constraint to ensure periodicity as a novel application for modelling daily blood pressure. Data from the Mitchelstown Study, a cross-sectional study of Irish adults aged 47-73 years (n = 2047) was utilized. A subsample (1207) underwent 24-h ABPM. We compared patterns between those with and without evidence of subclinical target organ damage (microalbuminuria).

Results: We were able to quantify the steepest rise and fall in SBP, which occurred just after waking (2.23 mmHg/30 min) and immediately after falling asleep (-1.93 mmHg/30 min) respectively. The variation about an individual's trajectory over 24 h was 12.3 mmHg (standard deviation). On average those with microalbuminuria were found to have significantly higher SBP (7.6 mmHg, 95% CI 5.0-10.1) after adjustment for age, sex and BMI. Including an interaction term between each linear spline and microalbuminuria did not improve model fit.

Conclusion: We have introduced a practical method for the analysis of ABPM where we can determine the rate of increase or decrease for different periods of the day. This may be particularly useful in examining chronotherapy effects of antihypertensive medication. It offers new measures of short-term BP variability as we can quantify the variation about an individual's trajectory but also allows examination of the variation in slopes between individuals (random-effects).
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http://dx.doi.org/10.1186/s12982-017-0055-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5290604PMC
February 2017

Correlation between short-term blood pressure variability and left-ventricular mass index: a meta-analysis.

Hypertens Res 2016 Mar 19;39(3):171-7. Epub 2015 Nov 19.

Department of Epidemiology and Public Health, University College Cork, Cork, Ireland.

Long-term blood pressure variability (BPV) has been associated with cardiovascular events but the prognostic significance of short-term BPV remains uncertain, including its influence on the presence of target-organ damage, specifically left-ventricular hypertrophy. A meta-analysis exploring the correlation between short-term BPV and left-ventricular mass index was performed. Studies were identified by systematic searches in Pubmed and EMBASE. Any summary measure of short-term BPV obtained from ambulatory blood pressure monitoring was included. Twelve studies were included. Average real variability (ARV), s.d., weighted s.d. and coefficient of variation across 24 h/day/night periods were identified as measures of variability. Meta-analysis showed the pooled subgroup correlation coefficients of LVMI with 24 h systolic blood pressure (SBP) s.d., day SBP s.d., weighted s.d. SBP and 24 h ARV SBP were 0.22 (95% confidence interval (CI): 0.12-0.31), 0.19 (95% CI: 0.15-0.25), 0.23 (95% CI: 0.13-0.33), 0.37 (95% CI: 0.01-0.65), respectively. This meta-analysis suggests there is a weak positive correlation, between BPV and LVMI.
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http://dx.doi.org/10.1038/hr.2015.126DOI Listing
March 2016

Isolated nocturnal hypertension and subclinical target organ damage: a systematic review of the literature.

Hypertens Res 2015 Aug 2;38(8):570-5. Epub 2015 Apr 2.

Department of Epidemiology and Public Health, University College Cork, Cork, Ireland.

Isolated nocturnal hypertension (INH) is associated with greater mortality and cardiovascular events. Subclinical target organ damage (TOD) is a prognostic marker for cardiovascular events. Our objective is to systematically summarize evidence on the association between INH and subclinical TOD. Observational population studies were considered. INH was defined as nighttime blood pressure (BP) ⩾120 and/or 70 mm Hg with daytime BP <135/85 mm Hg. We systematically searched Pubmed, EMBASE and the Cochrane Library. Abstracts were reviewed by two assessors. Potentially eligible articles were compared with inclusion criteria. The search yielded 954 titles, 13 abstracts were selected for review and four articles fulfilled inclusion criteria. INH was associated with higher ambulatory arterial stiffness index (0.4 unit vs. 0.35 unit, P<0.05), pulse wave velocity (16.2 m s(-1) vs. 14.7 m s(-1), P<0.05), central (140.4% vs. 134.0%, P<0.05) and peripheral (82.6% vs. 76.5%, P<0.01) augmentation index in a Chinese study. In the same population there was no association with left ventricular hypertrophy documented by electrocardiogram. INH was not associated with increased arterial stiffness or left venticular mass index in a Swedish study. An American study demonstrated higher left ventricular mass (152.46 g vs. 136.16 g, P=0.01) and greater odds of left ventricular hypertrophy (odds ratio 3.03, 95% confidence interval 1.02-9.05) in unadjusted analysis. There was no association with proteinuria. Evidence is inconclusive regarding the association between INH and subclinical TOD. Future research should focus on trying to elucidate the mechanisms that generate INH and contribute to the higher mortality associated with this BP pattern.
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http://dx.doi.org/10.1038/hr.2015.43DOI Listing
August 2015

Applying the ideal cardiovascular health metrics to couples: a cross-sectional study in primary care.

Clin Cardiol 2015 Jan 5;38(1):32-8. Epub 2015 Jan 5.

Department of Epidemiology and Public Health, University College Cork, Cork, Ireland.

Background: There is little research on overall cardiovascular (CV) health among couples. Our aim was to examine concordance levels for CV health among couples, using the American Heart Association ideal health metrics, and to investigate if the CV health of an individual is associated with that of his or her partner.

Hypothesis: There is a positive association between the overall cardiovascular health of an individual and that of his/her partner.

Methods: The Mitchelstown Study is a community-based cohort study of middle-aged Irish adults. Potential couples were identified as 2 study participants living at the same address. This list was cross-referenced with self-reported marital status and telephone number in the electronic patient record. Information on CV health metrics (smoking, body mass index, physical activity, diet, blood pressure, cholesterol, and glucose) was collected using standardized methods. Participants were categorized as ideal, intermediate, or poor for each of the metrics and for overall CV health. The 0- to 14-point CV health metrics score was compared within couples using linear regression.

Results: Of 2047 participants, 191 potential couples were identified. We excluded 6 sibling pairs, 1 divorced couple, and 3 couples who self-reported being single. The analysis includes 181 couples. There were significant associations between partners for smoking, diet, blood pressure, cholesterol, and glucose (P < 0.05). No couple had ideal CV health (ie, both partners with 7 ideal metrics). Most couples (n = 127, 69%) were concordant for poor CV health. There was a significant relationship between partners for the CV health metrics score (P < 0.05).

Conclusions: Our results suggest an individual's CV health is associated with that of his or her partner. Therefore, prevention strategies targeting couples and families may be appropriate.
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http://dx.doi.org/10.1002/clc.22350DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6711025PMC
January 2015

Prevalence of diabetes in the Republic of Ireland: results from the National Health Survey (SLAN) 2007.

PLoS One 2013 16;8(10):e78406. Epub 2013 Oct 16.

Institute of Public Health in Ireland, Dublin, Ireland.

Background: Current estimates of diabetes prevalence in the Republic of Ireland (RoI) are based on UK epidemiological studies. This study uses Irish data to describe the prevalence of doctor-diagnosed diabetes amongst all adults aged 18+ years and undiagnosed diabetes amongst those aged 45+ years.

Methods: The survey of lifestyle attitudes and nutrition (SLAN) 2007 is based on a nationally representative sample of Irish adults aged 18+ years (n = 10,364). Self-reported doctor-diagnosed diabetes was recorded for respondents in the full sample. Diabetes medication use, measured height and weight, and non-fasting blood samples were variously recorded in sub-samples of younger (n = 967) and older (n = 1,207) respondents.

Results: The prevalence of doctor-diagnosed diabetes amongst adults aged 18+ years was 3.5% (95% CI 3.1%-3.9%). After adjustment for other explanatory variables; the risk of self-reported doctor-diagnosed diabetes was significantly related to age (p < 0.0001), employment status (p = 0.0003) and obesity (p = 0.0003).Amongst adults aged 45+ years, the prevalence of doctor-diagnosed diabetes was 6.1% (95% CI 5.3% - 6.9% ) [corrected] and undiagnosed diabetes was 2.8% (95% CI 1.4% - 4.1%). This represented 31.2% of diabetes cases in this age group.

Conclusion: Notwithstanding methodological differences, these prevalence estimates are consistent with those in the UK and France. However, the percentage of undiagnosed cases amongst adults aged 45+ years appears to be higher in the RoI. Increased efforts to improve early detection and population level interventions to address adverse diet and lifestyle factors are urgently needed.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0078406PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3797781PMC
June 2014
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