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    1676 results match your criteria BMC Medical Research Methodology [Journal]

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    The appropriateness of Bland-Altman's approximate confidence intervals for limits of agreement.
    BMC Med Res Methodol 2018 May 22;18(1):45. Epub 2018 May 22.
    Department of Management Science, National Chiao Tung University, Hsinchu, 30010, Taiwan, Republic of China.
    Background: Percentiles are widely used as reference limits for determining the relative magnitude and substantial importance of quantitative measurements. An important application is the advocated Bland-Altman limits of agreement.

    Methods: To contribute to the data analysis and design planning of reference limit or percentile research, the purpose of this paper is twofold. Read More

    Methods to systematically review and meta-analyse observational studies: a systematic scoping review of recommendations.
    BMC Med Res Methodol 2018 May 21;18(1):44. Epub 2018 May 21.
    Department of Pathology and Biomedical Science, University of Otago, Christchurch, New Zealand.
    Background: Systematic reviews and meta-analyses of observational studies are frequently performed, but no widely accepted guidance is available at present. We performed a systematic scoping review of published methodological recommendations on how to systematically review and meta-analyse observational studies.

    Methods: We searched online databases and websites and contacted experts in the field to locate potentially eligible articles. Read More

    Validation of verbal autopsy methods using hospital medical records: a case study in Vietnam.
    BMC Med Res Methodol 2018 May 18;18(1):43. Epub 2018 May 18.
    Department of Global Health, Research School of Population Health, ANU College of Health and Medicine, Australian National University, Canberra, Australia.
    Background: Information on causes of death (COD) is crucial for measuring the health outcomes of populations and progress towards the Sustainable Development Goals. In many countries such as Vietnam where the civil registration and vital statistics (CRVS) system is dysfunctional, information on vital events will continue to rely on verbal autopsy (VA) methods. This study assesses the validity of VA methods used in Vietnam, and provides recommendations on methods for implementing VA validation studies in Vietnam. Read More

    Simulation-based power calculations for planning a two-stage individual participant data meta-analysis.
    BMC Med Res Methodol 2018 May 18;18(1):41. Epub 2018 May 18.
    Centre for Prognosis Research, Research Institute for Primary Care and Health Sciences, Keele University, Keele, Staffordshire, ST5 5BG, UK.
    Background: Researchers and funders should consider the statistical power of planned Individual Participant Data (IPD) meta-analysis projects, as they are often time-consuming and costly. We propose simulation-based power calculations utilising a two-stage framework, and illustrate the approach for a planned IPD meta-analysis of randomised trials with continuous outcomes where the aim is to identify treatment-covariate interactions.

    Methods: The simulation approach has four steps: (i) specify an underlying (data generating) statistical model for trials in the IPD meta-analysis; (ii) use readily available information (e. Read More

    Influence of blinding on treatment effect size estimate in randomized controlled trials of oral health interventions.
    BMC Med Res Methodol 2018 May 18;18(1):42. Epub 2018 May 18.
    Division of Orthodontics, School of Dentistry, University of Alberta, Edmonton, Canada.
    Background: Recent methodologic evidence suggests that lack of blinding in randomized trials can result in under- or overestimation of the treatment effect size. The objective of this study is to quantify the extent of bias associated with blinding in randomized controlled trials of oral health interventions.

    Methods: We selected all oral health meta-analyses that included a minimum of five randomized controlled trials. Read More

    Informative graphing of continuous safety variables relative to normal reference limits.
    BMC Med Res Methodol 2018 May 16;18(1):40. Epub 2018 May 16.
    Division of Neurology Products, Food and Drug Administration, Silver Spring, MD, USA.
    Background: Interpreting graphs of continuous safety variables can be complicated because differences in age, gender, and testing site methodologies data may give rise to multiple reference limits. Furthermore, data below the lower limit of normal are compressed relative to those points above the upper limit of normal. The objective of this study is to develop a graphing technique that addresses these issues and is visually intuitive. Read More

    Validating the use of veterans affairs tobacco health factors for assessing change in smoking status: accuracy, availability, and approach.
    BMC Med Res Methodol 2018 May 11;18(1):39. Epub 2018 May 11.
    Center for Chronic Disease Outcomes Research, Minneapolis VA Health Care System, Veterans Drive, Minneapolis, MN, 55417, USA.
    Background: Accurate smoking status is key for research purposes, but can be costly and difficult to measure. Within the Veteran's Health Administration (VA), smoking status is recorded as part of routine care as "health factors" (HF)-fields that researchers can query through the electronic health record (EHR). Many researchers are interested in using these fields to track changes in smoking status over time, however the validity of this measure for assessing change is unknown. Read More

    Nature and reporting characteristics of UK health technology assessment systematic reviews.
    BMC Med Res Methodol 2018 May 8;18(1):35. Epub 2018 May 8.
    School of Health and Related Research (ScHARR), University of Sheffield, Regent Court, Regent, Street, Sheffield, S1 4DA, UK.
    Background: A recent study by Page et al. (PLoS Med. 2016;13(5):e1002028) claimed that increasing numbers of reviews are being published and many are poorly-conducted and reported. Read More

    Comparison of methodological quality rating of systematic reviews on neuropathic pain using AMSTAR and R-AMSTAR.
    BMC Med Res Methodol 2018 May 8;18(1):37. Epub 2018 May 8.
    Laboratory for Pain Research, University of Split School of Medicine, Soltanska 2, 21000, Split, Croatia.
    Background: Systematic reviews (SRs) in the field of neuropathic pain (NeuP) are increasingly important for decision-making. However, methodological flaws in SRs can reduce the validity of conclusions. Hence, it is important to assess the methodological quality of NeuP SRs critically. Read More

    Measuring colorectal cancer incidence: the performance of an algorithm using administrative health data.
    BMC Med Res Methodol 2018 May 8;18(1):38. Epub 2018 May 8.
    Department of Social and Preventive Medicine, École de santé publique, Université de Montréal , C.P. 6128, succursale Centre-ville, Montreal, QC, H3C3J7, Canada.
    Background: Certain cancer case ascertainment methods used in Quebec and elsewhere are known to underestimate the burden of cancer, particularly for some subgroups. Algorithms using claims data are a low-cost option to improve the quality of cancer surveillance, but have not frequently been implemented at the population-level. Our objectives were to 1) develop a colorectal cancer (CRC) case ascertainment algorithm using population-level hospitalization and physician billing data, 2) validate the algorithm, and 3) describe the characteristics of cases. Read More

    Colliding ideals - an interview study of how intervention researchers address adherence and adaptations in replication studies.
    BMC Med Res Methodol 2018 May 8;18(1):36. Epub 2018 May 8.
    Medical Management Centre, Department of Learning, Informatics, Management, & Ethics, Karolinska Institutet, Stockholm, Sweden.
    Background: For an intervention to be considered evidence-based, findings need to be replicated. When this is done in new contexts (e.g. Read More

    Writing a discussion section: how to integrate substantive and statistical expertise.
    BMC Med Res Methodol 2018 Apr 17;18(1):34. Epub 2018 Apr 17.
    Faculty of Psychology, Technische Universität Dresden, Dresden, Germany.
    Background: When discussing results medical research articles often tear substantive and statistical (methodical) contributions apart, just as if both were independent. Consequently, reasoning on bias tends to be vague, unclear and superficial. This can lead to over-generalized, too narrow and misleading conclusions, especially for causal research questions. Read More

    Correction to: joint models for longitudinal and time-to-event data: a review of reporting quality with a view to meta-analysis.
    BMC Med Res Methodol 2018 Apr 4;18(1):33. Epub 2018 Apr 4.
    Department of Biostatistics, Block F Waterhouse Building, University of Liverpool, 1-5 Brownlow Street, Liverpool, L69 3GL, UK.
    Following publication of the original article [1] the authors reported that reference 15 (Cella et al.) had been incorrectly replaced with a duplicate of Brombin et al. during publication. Read More

    Sample size determination for mediation analysis of longitudinal data.
    BMC Med Res Methodol 2018 Mar 27;18(1):32. Epub 2018 Mar 27.
    Department of Biostatistics, Department of Biostatistics, Unit 1411, Anderson Cancer Center, The University of Texas MD, 1515 Holcombe Blvd, Houston, TX, 77030, USA.
    Background: Sample size planning for longitudinal data is crucial when designing mediation studies because sufficient statistical power is not only required in grant applications and peer-reviewed publications, but is essential to reliable research results. However, sample size determination is not straightforward for mediation analysis of longitudinal design.

    Methods: To facilitate planning the sample size for longitudinal mediation studies with a multilevel mediation model, this article provides the sample size required to achieve 80% power by simulations under various sizes of the mediation effect, within-subject correlations and numbers of repeated measures. Read More

    Using bundle embeddings to predict daily cortisol levels in human subjects.
    BMC Med Res Methodol 2018 Mar 21;18(1):31. Epub 2018 Mar 21.
    Department of Developmental Psychology, Heymans Institute for Psychological Research, University of Groningen, Faculty of Behavioural and Social Sciences, Grote Kruisstraat 2/1, 9712, TS, Groningen, the Netherlands.
    Background: Many biological variables sampled from human subjects show a diurnal pattern, which poses special demands on the techniques used to analyze such data. Furthermore, most biological variables belong to nonlinear dynamical systems, which may make linear statistical techniques less suitable to analyze their dynamics. The current study investigates the usefulness of two analysis techniques based on nonlinear lagged vector embeddings: sequentially weighted global linear maps (SMAP), and bundle embeddings. Read More

    Quality assessment of systematic reviews on total hip or knee arthroplasty using mod-AMSTAR.
    BMC Med Res Methodol 2018 Mar 16;18(1):30. Epub 2018 Mar 16.
    Department of Evidence-based Medicine and Clinical Epidemiology, West China Hospital, Sichuan University, Chengdu, Sichuan, 610041, China.
    Background: Increasing numbers of systematic reviews (SRs) on total knee arthroplasty (TKA) and total hip arthroplasty (THA) have been published in recent years, but their quality has been unclear. The purpose of this study is to evaluate the methodological quality of SRs on TKA and THA.

    Methods: We searched Ovid-Medline, Ovid-Embase, Cochrane Databases (including HTA, DARE, and CDSR), CBM, CNKI, Wang Fang, and VIP, from January 2014 to December 2015 for THA and TKA. Read More

    Psychometric properties and population norms of the positive mental health instrument in a representative multi-ethnic Asian population.
    BMC Med Res Methodol 2018 Mar 15;18(1):29. Epub 2018 Mar 15.
    Saw Swee Hock School of Public Health and Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore, Singapore.
    Background: Measures of mental well-being and positive mental health (PMH) have been largely developed and used in Western populations, however, data on representative Asian communities are lacking. Using data from a population sample, this study sought to establish psychometric properties and norms of the PMH Instrument (PMH-I), a measure of positive mental health developed in Singapore.

    Methods: We conducted a nationally representative survey among 1925 adults aged 18-79 years of Chinese, Malay, Indian or other ethnicity. Read More

    Methodological and clinical implications of a three-in-one Russian doll design for tracking health trajectories and improving health and function through innovative exercise treatments in adults with disability.
    BMC Med Res Methodol 2018 Mar 14;18(1):28. Epub 2018 Mar 14.
    Department of Health Services Administration, School of Health Professions, University of Alabama at Birmingham, 1716 9th Ave. South, Birmingham, AL, 35294-1212, USA.
    Background: Hybrid research designs targeting adults with neurologic disability are critical for improving the efficiency of models that can identify, track and intervene on identified health issues.

    Methods: Our Russian doll framework encompasses three study phases. Phase 1 involves prospectively following a cohort of participants with disability to examine the relationships between rates of health and functional deficits (e. Read More

    An application of restricted mean survival time in a competing risks setting: comparing time to ART initiation by injection drug use.
    BMC Med Res Methodol 2018 Mar 9;18(1):27. Epub 2018 Mar 9.
    Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, 615 N Wolfe St, Baltimore, MD, 21205, USA.
    Background: Restricted mean survival time (RMST) is an underutilized estimand in time-to-event analyses. Herein, we highlight its strengths by comparing time to (1) all-cause mortality and (2) initiation of antiretroviral therapy (ART) for HIV-infected persons who inject drugs (PWID) and persons who do not inject drugs.

    Methods: RMST to death was determined by integrating the Kaplan-Meier survival curve to 5 years of follow-up. Read More

    Pragmatism in practice: lessons learned during screening and enrollment for a randomised controlled trial in rural northern Ethiopia.
    BMC Med Res Methodol 2018 Mar 7;18(1):26. Epub 2018 Mar 7.
    Wellcome Trust Centre for Global Health Research, Brighton & Sussex Medical School, University of Sussex, Brighton, BN1 9PX, UK.
    Background: We use the example of the Gojjam Lymphoedema Best Practice Trial (GoLBeT), a pragmatic trial in a remote rural setting in northern Ethiopia, to extract lessons relevant to other investigators balancing the demands of practicality and community acceptability with internal and external validity in clinical trials.

    Methods: We explain in detail the preparation for the trial, its setting in northern Ethiopia, the identification and selection of patients (inclusion and exclusion criterion, identifying and screening of patients at home, enrollment of patients at the health centres and health posts), and randomisation.

    Results: We describe the challenges met, together with strategies employed to overcome them. Read More

    Dealing with missing standard deviation and mean values in meta-analysis of continuous outcomes: a systematic review.
    BMC Med Res Methodol 2018 Mar 7;18(1):25. Epub 2018 Mar 7.
    Nursing, Midwifery and Allied Health Professions Research Unit, Glasgow Caledonian University, Glasgow, UK.
    Background: Rigorous, informative meta-analyses rely on availability of appropriate summary statistics or individual participant data. For continuous outcomes, especially those with naturally skewed distributions, summary information on the mean or variability often goes unreported. While full reporting of original trial data is the ideal, we sought to identify methods for handling unreported mean or variability summary statistics in meta-analysis. Read More

    DeepSurv: personalized treatment recommender system using a Cox proportional hazards deep neural network.
    BMC Med Res Methodol 2018 Feb 26;18(1):24. Epub 2018 Feb 26.
    Applied Mathematics Program, Yale University, 51 Prospect Street, New Haven, 06511, CT, USA.
    Background: Medical practitioners use survival models to explore and understand the relationships between patients' covariates (e.g. clinical and genetic features) and the effectiveness of various treatment options. Read More

    Advantages of a multi-state approach in surgical research: how intermediate events and risk factor profile affect the prognosis of a patient with locally advanced rectal cancer.
    BMC Med Res Methodol 2018 Feb 13;18(1):23. Epub 2018 Feb 13.
    Department of Medical Statistics and Bioinformatics, Leiden University Medical Center (LUMC), Leiden, Netherlands.
    Background: Standard survival analysis fails to give insight into what happens to a patient after a first outcome event (like first relapse of a disease). Multi-state models are a useful tool for analyzing survival data when different treatments and results (intermediate events) can occur. Aim of this study was to implement a multi-state model on data of patients with rectal cancer to illustrate the advantages of multi-state analysis in comparison to standard survival analysis. Read More

    Correction to: Multiple Score Comparison: a network meta-analysis approach to comparison and external validation of prognostic scores.
    BMC Med Res Methodol 2018 Feb 12;18(1):21. Epub 2018 Feb 12.
    Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Zurich, Switzerland.
    Correction: Following publication of the original article [1], a member of the writing group reported that his name is misspelt. The paper should appear in Pubmed under "Ter Riet G", bot as "Riet GT". Read More

    The management of children with bronchiolitis in the Australasian hospital setting: development of a clinical practice guideline.
    BMC Med Res Methodol 2018 Feb 12;18(1):22. Epub 2018 Feb 12.
    Children's Emergency Department, Starship Children's Hospital, Private Bag 92024, Auckland, 1142, New Zealand.
    Background: Bronchiolitis is the commonest respiratory infection in children less than 12 months and cause of hospitalisation in infants under 6 months of age in Australasia. Unfortunately there is substantial variation in management, despite high levels of supporting evidence. This paper reports on the process, strengths and challenges of the hybrid approach used to develop the first Australasian management guideline relevant to the local population. Read More

    Value of information methods to design a clinical trial in a small population to optimise a health economic utility function.
    BMC Med Res Methodol 2018 Feb 8;18(1):20. Epub 2018 Feb 8.
    Statistics and Epidemiology, Division of Health Sciences, Warwick Medical School, University of Warwick, Coventry, UK.
    Background: Most confirmatory randomised controlled clinical trials (RCTs) are designed with specified power, usually 80% or 90%, for a hypothesis test conducted at a given significance level, usually 2.5% for a one-sided test. Approval of the experimental treatment by regulatory agencies is then based on the result of such a significance test with other information to balance the risk of adverse events against the benefit of the treatment to future patients. Read More

    Factor structure and psychometric properties of the english version of the trier inventory for chronic stress (TICS-E).
    BMC Med Res Methodol 2018 Feb 6;18(1):18. Epub 2018 Feb 6.
    University Medical Center of the Johannes Gutenberg University Mainz, Langenbeckstraße 1, 55131, Mainz, Germany.
    Background: Demands placed on individuals in occupational and social settings, as well as imbalances in personal traits and resources, can lead to chronic stress. The Trier Inventory for Chronic Stress (TICS) measures chronic stress while incorporating domain-specific aspects, and has been found to be a highly reliable and valid research tool. The aims of the present study were to confirm the German version TICS factorial structure in an English translation of the instrument (TICS-E) and to report its psychometric properties. Read More

    Using an onset-anchored Bayesian hierarchical model to improve predictions for amyotrophic lateral sclerosis disease progression.
    BMC Med Res Methodol 2018 Feb 6;18(1):19. Epub 2018 Feb 6.
    Department of Biostatistics, University of Kansas Medical Center, Kansas City, KS, USA.
    Background: Amyotrophic Lateral Sclerosis (ALS), also known as Lou Gehrig's disease, is a rare disease with extreme between-subject variability, especially with respect to rate of disease progression. This makes modelling a subject's disease progression, which is measured by the ALS Functional Rating Scale (ALSFRS), very difficult. Consider the problem of predicting a subject's ALSFRS score at 9 or 12 months after a given time-point. Read More

    Correction to: On the use of the outcome variable "small for gestational age" when gestational age is a potential mediator: a maternal asthma perspective.
    BMC Med Res Methodol 2018 Jan 29;18(1):17. Epub 2018 Jan 29.
    Department of Mathematics, Université du Québec à Montréal, C.P. 8888, Succursale Centre-ville, Montréal, Québec, H3C 3P8, Canada.
    Correction: Following publication of the original article [1], the authors reported that the following four references in Table 2 are incorrect. Read More

    Defeat and entrapment: more than meets the eye? Applying network analysis to estimate dimensions of highly correlated constructs.
    BMC Med Res Methodol 2018 Jan 25;18(1):16. Epub 2018 Jan 25.
    NIVEL, Netherlands Institute for Health Services Research, Utrecht, the Netherlands.
    Background: Defeat and entrapment have been shown to be of central relevance to the development of different disorders. However, it remains unclear whether they represent two distinct constructs or one overall latent variable. One reason for the unclarity is that traditional factor analytic techniques have trouble estimating the right number of clusters in highly correlated data. Read More

    Studying medical communication with video vignettes: a randomized study on how variations in video-vignette introduction format and camera focus influence analogue patients' engagement.
    BMC Med Res Methodol 2018 Jan 19;18(1):15. Epub 2018 Jan 19.
    Department of Medical Psychology, Academic Medical Center, University of Amsterdam, P.O. Box 22660, 1100, DD, Amsterdam, the Netherlands.
    Background: Video vignettes are used to test the effects of physicians' communication on patient outcomes. Methodological choices in video-vignette development may have far-stretching consequences for participants' engagement with the video, and thus the ecological validity of this design. To supplement the scant evidence in this field, this study tested how variations in video-vignette introduction format and camera focus influence participants' engagement with a video vignette showing a bad news consultation. Read More

    Assessing the effect of a partly unobserved, exogenous, binary time-dependent covariate on survival probabilities using generalised pseudo-values.
    BMC Med Res Methodol 2018 Jan 19;18(1):14. Epub 2018 Jan 19.
    Center for Medical Statistics, Informatics, and Intelligent Systems, Medical University of Vienna, Spitalgasse 23, A-1090, Vienna, Austria.
    Background: Investigating the impact of a time-dependent intervention on the probability of long-term survival is statistically challenging. A typical example is stem-cell transplantation performed after successful donor identification from registered donors. Here, a suggested simple analysis based on the exogenous donor availability status according to registered donors would allow the estimation and comparison of survival probabilities. Read More

    Does different information disclosure on placebo control affect blinding and trial outcomes? A case study of participant information leaflets of randomized placebo-controlled trials of acupuncture.
    BMC Med Res Methodol 2018 Jan 18;18(1):13. Epub 2018 Jan 18.
    Acupuncture and Meridian Science Research Centre, College of Korean Medicine, Kyung Hee University, Seoul, 02447, South Korea.
    Background: While full disclosure of information on placebo control in participant information leaflets (PILs) in a clinical trial is ethically required during informed consent, there have been concerning voices such complete disclosures may increase unnecessary nocebo responses, breach double-blind designs, and/or affect direction of trial outcomes. Taking an example of acupuncture studies, we aimed to examine what participants are told about placebo controls in randomized, placebo-controlled trials, and how it may affect blinding and trial outcomes.

    Methods: Authors of published randomized, placebo-controlled trials of acupuncture were identified from PubMed search and invited to provide PILs for their trials. Read More

    Getting messier with TIDieR: embracing context and complexity in intervention reporting.
    BMC Med Res Methodol 2018 Jan 18;18(1):12. Epub 2018 Jan 18.
    NIHR CLAHRC Greater Manchester, Manchester, UK.
    Background: The Template for Intervention Description and Replication (TIDieR) checklist and guide was developed by an international team of experts to promote full and accurate description of trial interventions. It is now widely used in health research. The aim of this paper is to describe the experience of using TIDieR outside of trials, in a range of applied health research contexts, and make recommendations on its usefulness in such settings. Read More

    Development and validation of self-reported line drawings of the modified Beighton score for the assessment of generalised joint hypermobility.
    BMC Med Res Methodol 2018 Jan 17;18(1):11. Epub 2018 Jan 17.
    Division of Rheumatology, Orthopaedics and Dermatology, School of Medicine, University of Nottingham, Nottingham, England.
    Background: The impracticalities and comparative expense of carrying out a clinical assessment is an obstacle in many large epidemiological studies. The purpose of this study was to develop and validate a series of electronic self-reported line drawing instruments based on the modified Beighton scoring system for the assessment of self-reported generalised joint hypermobility.

    Methods: Five sets of line drawings were created to depict the 9-point Beighton score criteria. Read More

    Reporting of heterogeneity of treatment effect in cohort studies: a review of the literature.
    BMC Med Res Methodol 2018 Jan 12;18(1):10. Epub 2018 Jan 12.
    INSERM U1153, ECAMO, METHODS, 27 rue du faubourg Saint-Jacques, Université Paris-Descartes, 75014, Paris 5, France.
    Background: This article corresponds to a literature review and analyze how heterogeneity of treatment (HTE) is reported and addressed in cohort studies and to evaluate the use of the different measures to HTE analysis.

    Methods: prospective cohort studies, in English language, measuring the effect of a treatment (pharmacological, interventional, or other) published among 119 core clinical journals (defined by the National Library of Medicine) in the last 16 years were selected in the following data source: Medline. One reviewer randomly sampled journal articles with 1: 1 stratification by journal type: high impact journals (the New England Journal of Medicine, JAMA, LANCET, Annals of Internal Medicine, BMJ and Plos Medicine) and low impact journal (the remaining journals) to identify 150 eligible studies. Read More

    A systematic review of comparisons between protocols or registrations and full reports in primary biomedical research.
    BMC Med Res Methodol 2018 Jan 11;18(1). Epub 2018 Jan 11.
    Department of Health Research Methods, Evidence, and Impact, McMaster University, St. Joseph's Healthcare, Hamilton, 501-25 Charlton Avenue East, Hamilton, ON, L8N 1Y2, Canada.
    Background: Prospective study protocols and registrations can play a significant role in reducing incomplete or selective reporting of primary biomedical research, because they are pre-specified blueprints which are available for the evaluation of, and comparison with, full reports. However, inconsistencies between protocols or registrations and full reports have been frequently documented. In this systematic review, which forms part of our series on the state of reporting of primary biomedical, we aimed to survey the existing evidence of inconsistencies between protocols or registrations (i. Read More

    A multiple imputation method based on weighted quantile regression models for longitudinal censored biomarker data with missing values at early visits.
    BMC Med Res Methodol 2018 Jan 11;18(1). Epub 2018 Jan 11.
    Division of Rheumatology, Department of Internal Medicine, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas, USA.
    Background: In patient-based studies, biomarker data are often subject to left censoring due to the detection limits, or to incomplete sample or data collection. In the context of longitudinal regression analysis, inappropriate handling of these issues could lead to biased parameter estimates. We developed a specific multiple imputation (MI) strategy based on weighted censored quantile regression (CQR) that not only accounts for censoring, but also missing data at early visits when longitudinal biomarker data are modeled as a covariate. Read More

    Comparison of nuisance parameters in pediatric versus adult randomized trials: a meta-epidemiologic empirical evaluation.
    BMC Med Res Methodol 2018 Jan 10;18(1). Epub 2018 Jan 10.
    Pediatric Clinical Research Office, Emma Children's Hospital, Academic Medical Centre, Amsterdam, Netherlands.
    Background: We wished to compare the nuisance parameters of pediatric vs. adult randomized-trials (RCTs) and determine if the latter can be used in sample size computations of the former.

    Methods: In this meta-epidemiologic empirical evaluation we examined meta-analyses from the Cochrane Database of Systematic-Reviews, with at least one pediatric-RCT and at least one adult-RCT. Read More

    What kind of systematic review should I conduct? A proposed typology and guidance for systematic reviewers in the medical and health sciences.
    BMC Med Res Methodol 2018 Jan 10;18(1). Epub 2018 Jan 10.
    The Joanna Briggs Institute, The University of Adelaide, 55 King William Road, North Adelaide, Soueth Australia, 5005, Australia.
    Background: Systematic reviews have been considered as the pillar on which evidence-based healthcare rests. Systematic review methodology has evolved and been modified over the years to accommodate the range of questions that may arise in the health and medical sciences. This paper explores a concept still rarely considered by novice authors and in the literature: determining the type of systematic review to undertake based on a research question or priority. Read More

    Structure formats of randomised controlled trial abstracts: a cross-sectional analysis of their current usage and association with methodology reporting.
    BMC Med Res Methodol 2018 Jan 10;18(1). Epub 2018 Jan 10.
    Cochrane Oral Health, Division of Dentistry, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester Academic Health Science Centre, Oxford Road, Manchester, M13 9PL, UK.
    Background: The reporting of randomised controlled trial (RCT) abstracts is of vital importance. The primary objective of this study was to investigate the association between structure format and RCT abstracts' quality of methodology reporting, informed by the current requirement and usage of structure formats by leading general medical/internal medicine journals (secondary objective).

    Methods: A two-part cross-sectional study. Read More

    A comparison of estimators from self-controlled case series, case-crossover design, and sequence symmetry analysis for pharmacoepidemiological studies.
    BMC Med Res Methodol 2018 Jan 8;18(1). Epub 2018 Jan 8.
    Department of Biostatistics, School of Public Health, Graduate School of Medicine, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, Japan.
    Background: Despite the frequent use of self-controlled methods in pharmacoepidemiological studies, the factors that may bias the estimates from these methods have not been adequately compared in real-world settings. Here, we comparatively examined the impact of a time-varying confounder and its interactions with time-invariant confounders, time trends in exposures and events, restrictions, and misspecification of risk period durations on the estimators from three self-controlled methods. This study analyzed self-controlled case series (SCCS), case-crossover (CCO) design, and sequence symmetry analysis (SSA) using simulated and actual electronic medical records datasets. Read More

    Effects of pre-notification, invitation length, questionnaire length and reminder on participation rate: a quasi-randomised controlled trial.
    BMC Med Res Methodol 2018 Jan 5;18(1). Epub 2018 Jan 5.
    Department of Oncology-Pathology, Karolinska Institutet. Karolinska University Hospital, Z1:00, 171 76, Stockholm, Sweden.
    Background: Improving participation rates in epidemiologic studies using questionnaires and biological sampling is important for the generalizability of the outcome. The aim of this study was to examine the effects of pre-notification, invitation length, questionnaire length, and reminder on participation rate and to investigate whether some factors contributed to participants doing both the questionnaire and blood sampling as oppose to only one part.

    Methods: Our study was embedded within the pilot testing of a large population-based study about prostate cancer screening. Read More

    Evaluating screening approaches for hepatocellular carcinoma in a cohort of HCV related cirrhosis patients from the Veteran's Affairs Health Care System.
    BMC Med Res Methodol 2018 Jan 4;18(1). Epub 2018 Jan 4.
    Baylor College of Medicine, Houston, USA.
    Background: Hepatocellular carcinoma (HCC) has limited treatment options in patients with advanced stage disease and early detection of HCC through surveillance programs is a key component towards reducing mortality. The current practice guidelines recommend that high-risk cirrhosis patients are screened every six months with ultrasonography but these are done in local hospitals with variable quality leading to disagreement about the benefit of HCC surveillance. The well-established diagnostic biomarker α-Fetoprotein (AFP) is used widely in screening but the reported performance varies widely across studies. Read More

    A systematic comparison of recurrent event models for application to composite endpoints.
    BMC Med Res Methodol 2018 Jan 4;18(1). Epub 2018 Jan 4.
    Institute of Medical Biometry and Informatics, Universtiy Medical Center Ruprecht-Karls Universtiy Heidelberg, Im Neuenheimer Feld 130.3, Heidelberg, 69120, Germany.
    Background: Many clinical trials focus on the comparison of the treatment effect between two or more groups concerning a rarely occurring event. In this situation, showing a relevant effect with an acceptable power requires the observation of a large number of patients over a long period of time. For feasibility issues, it is therefore often considered to include several event types of interest, non-fatal or fatal, and to combine them within a composite endpoint. Read More

    A scoping review of comparisons between abstracts and full reports in primary biomedical research.
    BMC Med Res Methodol 2017 12 29;17(1):181. Epub 2017 Dec 29.
    Department of Health Research Methods, Evidence, and Impact, McMaster University, Hamilton, ON, Canada.
    Background: Evidence shows that research abstracts are commonly inconsistent with their corresponding full reports, and may mislead readers. In this scoping review, which is part of our series on the state of reporting of primary biomedical research, we summarized the evidence from systematic reviews and surveys, to investigate the current state of inconsistent abstract reporting, and to evaluate factors associated with improved reporting by comparing abstracts and their full reports.

    Methods: We searched EMBASE, Web of Science, MEDLINE, and CINAHL from January 1st 1996 to September 30th 2016 to retrieve eligible systematic reviews and surveys. Read More

    Abstract analysis method facilitates filtering low-methodological quality and high-bias risk systematic reviews on psoriasis interventions.
    BMC Med Res Methodol 2017 12 29;17(1):180. Epub 2017 Dec 29.
    IMIBIC/Reina Sofía University Hospital/UNiversity of Córdoba, Menendez Pidal Ave, Córdoba, 14005, Spain.
    Background: Article summaries' information and structure may influence researchers/clinicians' decisions to conduct deeper full-text analyses. Specifically, abstracts of systematic reviews (SRs) and meta-analyses (MA) should provide structured summaries for quick assessment. This study explored a method for determining the methodological quality and bias risk of full-text reviews using abstract information alone. Read More

    Can statistic adjustment of OR minimize the potential confounding bias for meta-analysis of case-control study? A secondary data analysis.
    BMC Med Res Methodol 2017 12 29;17(1):179. Epub 2017 Dec 29.
    Department of Epidemiology and Biostatistics, School of Public Health, Capital Medical University, Beijing, China.
    Background: Different confounder adjustment strategies were used to estimate odds ratios (ORs) in case-control study, i.e. how many confounders original studies adjusted and what the variables are. Read More

    The alarming problems of confounding equivalence using logistic regression models in the perspective of causal diagrams.
    BMC Med Res Methodol 2017 12 28;17(1):177. Epub 2017 Dec 28.
    Department of Biostatistics, School of Public Health, Shandong University, Jinan, People's Republic of China.
    Background: Confounders can produce spurious associations between exposure and outcome in observational studies. For majority of epidemiologists, adjusting for confounders using logistic regression model is their habitual method, though it has some problems in accuracy and precision. It is, therefore, important to highlight the problems of logistic regression and search the alternative method. Read More

    Compliance of systematic reviews in ophthalmology with the PRISMA statement.
    BMC Med Res Methodol 2017 12 28;17(1):178. Epub 2017 Dec 28.
    Guy's and St. Thomas' NHS Foundation Trust and Balliol College, University of Oxford, Oxford, UK.
    Background: Systematic reviews and meta-analyses are becoming increasingly important methods to summarize published research. Studies of ophthalmology may present additional challenges because of their potentially complex study designs. The aim of this study was to evaluate the reporting quality of systematic reviews and meta-analyses on topics in ophthalmology to determine compliance with the PRISMA guidelines. Read More

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