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    1599 results match your criteria BMC Medical Research Methodology [Journal]

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    Design considerations and analysis planning of a phase 2a proof of concept study in rheumatoid arthritis in the presence of possible non-monotonicity.
    BMC Med Res Methodol 2017 Oct 2;17(1):149. Epub 2017 Oct 2.
    Medical Statistics Group, University of Sheffield, Sheffield, UK.
    Background: It is important to quantify the dose response for a drug in phase 2a clinical trials so the optimal doses can then be selected for subsequent late phase trials. In a phase 2a clinical trial of new lead drug being developed for the treatment of rheumatoid arthritis (RA), a U-shaped dose response curve was observed. In the light of this result further research was undertaken to design an efficient phase 2a proof of concept (PoC) trial for a follow-on compound using the lessons learnt from the lead compound. Read More

    Item response models for the longitudinal analysis of health-related quality of life in cancer clinical trials.
    BMC Med Res Methodol 2017 Sep 26;17(1):148. Epub 2017 Sep 26.
    Biometrics Unit, Institut du Cancer Montpellier, 208 Avenue des Apothicaires, Montpellier, 34298, France.
    Background: The use of health-related quality of life (HRQoL) as an endpoint in cancer clinical trials is growing rapidly. Hence, research into the statistical approaches used to analyze HRQoL data is of major importance, and could lead to a better understanding of the impact of treatments on the everyday life and care of patients. Amongst the models that are used for the longitudinal analysis of HRQoL, we focused on the mixed models from item response theory, to directly analyze raw data from questionnaires. Read More

    Predicting the multi-domain progression of Parkinson's disease: a Bayesian multivariate generalized linear mixed-effect model.
    BMC Med Res Methodol 2017 Sep 25;17(1):147. Epub 2017 Sep 25.
    Department of Neurology, Pennsylvania State University Hershey Medical Center, Hershey, PA, 17033, USA.
    Background: It is challenging for current statistical models to predict clinical progression of Parkinson's disease (PD) because of the involvement of multi-domains and longitudinal data.

    Methods: Past univariate longitudinal or multivariate analyses from cross-sectional trials have limited power to predict individual outcomes or a single moment. The multivariate generalized linear mixed-effect model (GLMM) under the Bayesian framework was proposed to study multi-domain longitudinal outcomes obtained at baseline, 18-, and 36-month. Read More

    Systematic review of statistical approaches to quantify, or correct for, measurement error in a continuous exposure in nutritional epidemiology.
    BMC Med Res Methodol 2017 Sep 19;17(1):146. Epub 2017 Sep 19.
    Population Health & Occupational Disease, National Heart and Lung Institute, Imperial College London, London, UK.
    Background: Several statistical approaches have been proposed to assess and correct for exposure measurement error. We aimed to provide a critical overview of the most common approaches used in nutritional epidemiology.

    Methods: MEDLINE, EMBASE, BIOSIS and CINAHL were searched for reports published in English up to May 2016 in order to ascertain studies that described methods aimed to quantify and/or correct for measurement error for a continuous exposure in nutritional epidemiology using a calibration study. Read More

    Pragmatic clinical trials embedded in healthcare systems: generalizable lessons from the NIH Collaboratory.
    BMC Med Res Methodol 2017 Sep 18;17(1):144. Epub 2017 Sep 18.
    Duke Clinical Research Institute, 2400 Pratt St., Durham, NC, 27710, USA.
    Background: The clinical research enterprise is not producing the evidence decision makers arguably need in a timely and cost effective manner; research currently involves the use of labor-intensive parallel systems that are separate from clinical care. The emergence of pragmatic clinical trials (PCTs) poses a possible solution: these large-scale trials are embedded within routine clinical care and often involve cluster randomization of hospitals, clinics, primary care providers, etc. Interventions can be implemented by health system personnel through usual communication channels and quality improvement infrastructure, and data collected as part of routine clinical care. Read More

    Patients' beliefs regarding informed consent for low-risk pragmatic trials.
    BMC Med Res Methodol 2017 Sep 18;17(1):145. Epub 2017 Sep 18.
    Section on Research Ethics, Department of Bioethics, NIH Clinical Center, 10 Center Dr, Bethesda, MD, 20814, USA.
    Background: The requirement to obtain written informed consent may undermine the potential of pragmatic randomized clinical trials (pRCTs) to improve evidence-based care. This requirement could compromise trials statistical power or even force it to close them down prematurely. However, recent data from the U. Read More

    Repeat: a framework to assess empirical reproducibility in biomedical research.
    BMC Med Res Methodol 2017 Sep 18;17(1):143. Epub 2017 Sep 18.
    Institute of Clinical and Translational Sciences, Washington University in St. Louis School of Medicine, 660 S. Euclid Ave, Box 8066, St. Louis, 63110, MO, USA.
    Background: The reproducibility of research is essential to rigorous science, yet significant concerns of the reliability and verifiability of biomedical research have been recently highlighted. Ongoing efforts across several domains of science and policy are working to clarify the fundamental characteristics of reproducibility and to enhance the transparency and accessibility of research.

    Methods: The aim of the proceeding work is to develop an assessment tool operationalizing key concepts of research transparency in the biomedical domain, specifically for secondary biomedical data research using electronic health record data. Read More

    Assessment of consent models as an ethical consideration in the conduct of prehospital ambulance randomised controlled clinical trials: a systematic review.
    BMC Med Res Methodol 2017 Sep 16;17(1):142. Epub 2017 Sep 16.
    Community and Health Research Unit, College of Social Science, University of Lincoln, Brayford Pool, Lincoln, LN6 7TS, UK.
    Background: We sought to understand the main ethical considerations when conducting clinical trials in the prehospital ambulance based setting.

    Methods: A systematic review of the literature on randomised controlled trials in ambulance settings was undertaken. A search of eight databases identified published studies involving recruitment of ambulance service users. Read More

    Reporting of the translation and cultural adaptation procedures of the Addenbrooke's Cognitive Examination version III (ACE-III) and its predecessors: a systematic review.
    BMC Med Res Methodol 2017 Sep 13;17(1):141. Epub 2017 Sep 13.
    Centre for Primary Care, The University of Manchester, Suite 6, 5th Floor, Williamson Building, Oxford Road, Manchester, M13 9PL, UK.
    Background: The ACE-III, a gold standard for screening cognitive impairment, is restricted by language and culture, with no uniform set of guidelines for its adaptation. To develop guidelines a compilation of all the adaptation procedures undertaken by adapters of the ACE-III and its predecessors is needed.

    Methods: We searched EMBASE, Medline and PsychINFO and screened publications from a previous review. Read More

    Conducting a team-based multi-sited focused ethnography in primary care.
    BMC Med Res Methodol 2017 Sep 12;17(1):139. Epub 2017 Sep 12.
    Nuffield Department of Primary Care Health Sciences, University of Oxford, Radcliffe Primary Care Building, Radcliffe Observatory Quarter, Woodstock Rd, Oxford, OX2 6GG, UK.
    Focused ethnography is an applied and pragmatic form of ethnography that explores a specific social phenomenon as it occurs in everyday life. Based on the literature a problem-focused research question is formulated before the data collection. The data generation process targets key informants and situations so that relevant results on the pre-defined topic can be obtained within a relatively short time-span. Read More

    Measuring the burden of treatment for chronic disease: implications of a scoping review of the literature.
    BMC Med Res Methodol 2017 Sep 12;17(1):140. Epub 2017 Sep 12.
    Menzies Health Institute Queensland, Griffith University, University Drive, Meadowbrook, QLD, Australia.
    Background: Although there has been growing research on the burden of treatment, the current state of evidence on measuring this concept is unknown. This scoping review aimed to provide an overview of the current state of knowledge as well as clear recommendations for future research, within the context of chronic disease.

    Methods: Four health-based databases, Scopus, CINAHL, Medline, and PsychInfo, were comprehensively searched for peer-reviewed articles published between the periods of 2000-2016. Read More

    Towards evidence-based computational statistics: lessons from clinical research on the role and design of real-data benchmark studies.
    BMC Med Res Methodol 2017 Sep 9;17(1):138. Epub 2017 Sep 9.
    Institute of Medical Statistics and Epidemiology, Technical University Munich, Ismaninger Str. 22, Munich, 81675, Germany.
    Background: The goal of medical research is to develop interventions that are in some sense superior, with respect to patient outcome, to interventions currently in use. Similarly, the goal of research in methodological computational statistics is to develop data analysis tools that are themselves superior to the existing tools. The methodology of the evaluation of medical interventions continues to be discussed extensively in the literature and it is now well accepted that medicine should be at least partly "evidence-based". Read More

    Evidence mapping based on systematic reviews of therapeutic interventions for gastrointestinal stromal tumors (GIST).
    BMC Med Res Methodol 2017 Sep 7;17(1):135. Epub 2017 Sep 7.
    Iberoamerican Cochrane Centre - Sant Pau Biomedical Research Institute, (IIB Sant Pau), CIBER Epidemiología y Salud Pública (CIBERESP), Universitat Autònoma de Barcelona, Barcelona, Spain.
    Background: Gastrointestinal Stromal Tumours (GISTs) are the most common mesenchymal tumours. Currently, different pharmacological and surgical options are used to treat localised and metastatic GISTs, although this research field is broad and the body of evidence is scattered and expanding. Our objectives are to identify, describe and organise the current available evidence for GIST through an evidence mapping approach. Read More

    Addressing data privacy in matched studies via virtual pooling.
    BMC Med Res Methodol 2017 Sep 7;17(1):136. Epub 2017 Sep 7.
    Biostatistics and Computational Biology Branch, National Institutes of Environmental Health Sciences, NIH, 111 T.W. Alexander Drive, RTP, Durham, NC, USA.
    Background: Data confidentiality and shared use of research data are two desirable but sometimes conflicting goals in research with multi-center studies and distributed data. While ideal for straightforward analysis, confidentiality restrictions forbid creation of a single dataset that includes covariate information of all participants. Current approaches such as aggregate data sharing, distributed regression, meta-analysis and score-based methods can have important limitations. Read More

    Monte Carlo simulation-based estimation for the minimum mortality temperature in temperature-mortality association study.
    BMC Med Res Methodol 2017 Sep 7;17(1):137. Epub 2017 Sep 7.
    Department of Mathematical Sciences, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea.
    Background: Rich literature has reported that there exists a nonlinear association between temperature and mortality. One important feature in the temperature-mortality association is the minimum mortality temperature (MMT). The commonly used approach for estimating the MMT is to determine the MMT as the temperature at which mortality is minimized in the estimated temperature-mortality association curve. Read More

    Longitudinal studies that use data collected as part of usual care risk reporting biased results: a systematic review.
    BMC Med Res Methodol 2017 Sep 6;17(1):133. Epub 2017 Sep 6.
    Child Health Evaluative Sciences, The Hospital for Sick Children, Toronto, ON, M5G 1X8, Canada.
    Background: Longitudinal studies using data collected as part of usual care risk providing biased results if visit times are related to the outcome of interest. Statistical methods for mitigating this bias are available but rarely used. This lack of use could be attributed to a lack of need or to a lack of awareness of the issue. Read More

    Multiple imputation for handling missing outcome data when estimating the relative risk.
    BMC Med Res Methodol 2017 Sep 6;17(1):134. Epub 2017 Sep 6.
    The University of Adelaide, School of Public Health, Adelaide, SA, Australia.
    Background: Multiple imputation is a popular approach to handling missing data in medical research, yet little is known about its applicability for estimating the relative risk. Standard methods for imputing incomplete binary outcomes involve logistic regression or an assumption of multivariate normality, whereas relative risks are typically estimated using log binomial models. It is unclear whether misspecification of the imputation model in this setting could lead to biased parameter estimates. Read More

    Factors associated with attrition in a longitudinal online study: results from the HaBIDS panel.
    BMC Med Res Methodol 2017 Aug 31;17(1):132. Epub 2017 Aug 31.
    Department of Epidemiology, Helmholtz Centre for Infection Research (HZI), Inhoffenstraße 7, 38124, Braunschweig, Germany.
    Background: Knowing about predictors of attrition in a panel is important to initiate early measures against loss of participants. We investigated attrition in both early and late phase of an online panel with special focus on preferences regarding mode of participation.

    Methods: We used data from the HaBIDS panel that was designed to investigate knowledge, attitudes, and practice regarding infections in the German general population. Read More

    Validity and reliability of a performance evaluation tool based on the modified Barthel Index for stroke patients.
    BMC Med Res Methodol 2017 Aug 25;17(1):131. Epub 2017 Aug 25.
    Department of Health Informatics, Kyoto University School of Public Health, Yoshida-Konoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan.
    Background: The Barthel Index (BI) is a measure of independence in activities of daily living (ADL). In the modified Barthel Index (MBI), a five-point system replaced the original two or three or four point rating system. Based on this modified measure, the performance evaluation tool MBI (PET-MBI) was developed in Japan. Read More

    Trends in the number and the quality of trial protocols involving children submitted to a French Institutional Review Board.
    BMC Med Res Methodol 2017 Aug 23;17(1):130. Epub 2017 Aug 23.
    Evolutive Biology and Biometric Laboratory UMR5558 CNRS, Université Claude Bernard Lyon 1, 8 rue Guillaume Paradin, BP8071, 69376-CEDEX-08, Lyon, France.
    Background: There is a great need for high quality clinical research for children. The European Pediatric Regulation aimed to improve the quality of clinical trials in order to increase the availability of treatments for children. The main purpose of this study was to assess the evolution of both the number and the quality of pediatric trial protocols that were submitted to a French Institutional Review Board (IRB00009118) before and after the initiation of the EU Pediatric Regulation. Read More

    Methods for significance testing of categorical covariates in logistic regression models after multiple imputation: power and applicability analysis.
    BMC Med Res Methodol 2017 Aug 22;17(1):129. Epub 2017 Aug 22.
    Department of Epidemiology & Biostatistics, VU University Medical Center, Amsterdam, The Netherlands.
    Background: Multiple imputation is a recommended method to handle missing data. For significance testing after multiple imputation, Rubin's Rules (RR) are easily applied to pool parameter estimates. In a logistic regression model, to consider whether a categorical covariate with more than two levels significantly contributes to the model, different methods are available. Read More

    Using Bayesian statistics to estimate the likelihood a new trial will demonstrate the efficacy of a new treatment.
    BMC Med Res Methodol 2017 Aug 22;17(1):128. Epub 2017 Aug 22.
    INSERM U1153, Paris, France.
    Background: The common frequentist approach is limited in providing investigators with appropriate measures for conducting a new trial. To answer such important questions and one has to look at Bayesian statistics.

    Methods: As a worked example, we conducted a Bayesian cumulative meta-analysis to summarize the benefit of patient-specific instrumentation on the alignment of total knee replacement from previously published evidence. Read More

    Statistical methods for elimination of guarantee-time bias in cohort studies: a simulation study.
    BMC Med Res Methodol 2017 Aug 22;17(1):126. Epub 2017 Aug 22.
    Department of Biostatistics and Medical Informatics, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul, 50-1, South Korea.
    Background: Aspirin has been considered to be beneficial in preventing cardiovascular diseases and cancer. Several pharmaco-epidemiology cohort studies have shown protective effects of aspirin on diseases using various statistical methods, with the Cox regression model being the most commonly used approach. However, there are some inherent limitations to the conventional Cox regression approach such as guarantee-time bias, resulting in an overestimation of the drug effect. Read More

    Why statistical inference from clinical trials is likely to generate false and irreproducible results.
    BMC Med Res Methodol 2017 Aug 22;17(1):127. Epub 2017 Aug 22.
    Department of Mathematics and Statistics, Idaho State University, 921 S. 8th Avenue, Stop 8085, Pocatello, ID, 83209-8085, USA.
    One area of biomedical research where the replication crisis is most visible and consequential is clinical trials. Why do outcomes of so many clinical trials contradict each other? Why is the effectiveness of many drugs and other medical interventions so low? Why have prescription medications become the third leading cause of death in the US and Europe after cardiovascular diseases and cancer? In answering these questions, the main culprits identified so far have been various biases and conflicts of interest in planning, execution and analysis of clinical trials as well as reporting their outcomes. In this work, we take an in-depth look at statistical methodology used in planning clinical trials and analyzing trial data. Read More

    Estimating correlation between multivariate longitudinal data in the presence of heterogeneity.
    BMC Med Res Methodol 2017 Aug 17;17(1):124. Epub 2017 Aug 17.
    Division of Biostatistics, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO, 63110, USA.
    Background: Estimating correlation coefficients among outcomes is one of the most important analytical tasks in epidemiological and clinical research. Availability of multivariate longitudinal data presents a unique opportunity to assess joint evolution of outcomes over time. Bivariate linear mixed model (BLMM) provides a versatile tool with regard to assessing correlation. Read More

    The impact of self-interviews on response patterns for sensitive topics: a randomized trial of electronic delivery methods for a sexual behaviour questionnaire in rural South Africa.
    BMC Med Res Methodol 2017 Aug 17;17(1):125. Epub 2017 Aug 17.
    Africa Health Research Institute, Mtubatuba, South Africa.
    Background: Self-interviews, where the respondent rather than the interviewer enters answers to questions, have been proposed as a way to reduce social desirability bias associated with interviewer-led interviews. Computer-assisted self-interviews (CASI) are commonly proposed since the computer programme can guide respondents; however they require both language and computer literacy. We evaluated the feasibility and acceptability of using electronic methods to administer quantitative sexual behaviour questionnaires in the Somkhele demographic surveillance area (DSA) in rural KwaZulu-Natal, South Africa. Read More

    Applied Swarm-based medicine: collecting decision trees for patterns of algorithms analysis.
    BMC Med Res Methodol 2017 Aug 16;17(1):123. Epub 2017 Aug 16.
    Department of Radiation Oncology, Kantonsspital St. Gallen, Rorschacherstrasse 95, 9007, St. Gallen, Switzerland.
    Background: The objective consensus methodology has recently been applied in consensus finding in several studies on medical decision-making among clinical experts or guidelines. The main advantages of this method are an automated analysis and comparison of treatment algorithms of the participating centers which can be performed anonymously.

    Methods: Based on the experience from completed consensus analyses, the main steps for the successful implementation of the objective consensus methodology were identified and discussed among the main investigators. Read More

    Trading certainty for speed - how much uncertainty are decisionmakers and guideline developers willing to accept when using rapid reviews: an international survey.
    BMC Med Res Methodol 2017 Aug 14;17(1):121. Epub 2017 Aug 14.
    Department for Evidence-based Medicine and Clinical Epidemiology, Danube University Krems, Cochrane Austria, Dr. Karl Dorrek Strasse 30, 3500, Krems, Austria.
    Background: Decisionmakers and guideline developers demand rapid syntheses of the evidence when time sensitive evidence-informed decisions are required. A potential trade-off of such rapid reviews is that their results can have less reliability than results of systematic reviews that can lead to an increased risk of making incorrect decisions or recommendations. We sought to determine how much incremental uncertainty about the correctness of an answer guideline developers and health policy decisionmakers are willing to accept in exchange for a rapid evidence-synthesis. Read More

    The impact of the lookback period and definition of confirmatory events on the identification of incident cancer cases in administrative data.
    BMC Med Res Methodol 2017 Aug 14;17(1):122. Epub 2017 Aug 14.
    Leibniz Institute for Prevention Research and Epidemiology - BIPS, Drug Safety Unit, Achterstrasse 30, 28359, Bremen, Germany.
    Background: This cohort study examined the impact of the lengths of lookback and confirmation periods as well as the definition of confirmatory events on the number of incident cancer cases identified and age-standardized cumulative incidences (ACI) estimated in administrative data using German cancer registry data as a benchmark.

    Methods: ACI per 100,000 insured persons for breast, prostate and colorectal cancer were estimated using BARMER Statutory Health Insurance claims data. Incident cancer cases were defined as having an in- or outpatient diagnosis in 2013, no diagnosis in a lookback period of 1 year and a second diagnosis (or death) in a confirmation period of 1 quarter. Read More

    Using classification and regression tree modelling to investigate response shift patterns in dentine hypersensitivity.
    BMC Med Res Methodol 2017 Aug 14;17(1):120. Epub 2017 Aug 14.
    School of Oral and Dental Sciences, University of Bristol, Bristol, UK.
    Background: Dentine hypersensitivity (DH) affects people's quality of life (QoL). However changes in the internal meaning of QoL, known as Response shift (RS) may undermine longitudinal assessment of QoL. This study aimed to describe patterns of RS in people with DH using Classification and Regression Trees (CRT) and to explore the convergent validity of CRT with the then-test and ideals approaches. Read More

    Choice of futility boundaries for group sequential designs with two endpoints.
    BMC Med Res Methodol 2017 Aug 8;17(1):119. Epub 2017 Aug 8.
    Institute of Medical Biometry and Informatics, University of Heidelberg, Im Neuenheimer Feld 130.3, Heidelberg, 69120, Germany.
    Background: In clinical trials, the opportunity for an early stop during an interim analysis (either for efficacy or for futility) may relevantly save time and financial resources. This is especially important, if the planning assumptions required for power calculation are based on a low level of evidence. For example, when including two primary endpoints in the confirmatory analysis, the power of the trial depends on the effects of both endpoints and on their correlation. Read More

    Programme Reporting Standards (PRS) for improving the reporting of sexual, reproductive, maternal, newborn, child and adolescent health programmes.
    BMC Med Res Methodol 2017 Aug 3;17(1):117. Epub 2017 Aug 3.
    Department of Reproductive Health and Research, including the UNDP/UNFPA/UNICEF/WHO/World Bank Special Programme of Research, Development and Research Training in Human Reproduction, World Health Organization, Geneva, Switzerland.
    Background: Information about design, implementation, monitoring and evaluation is central to understand the impact of programmes within the field of sexual, reproductive, maternal, newborn, child and adolescent health (SRMNCAH). Existing reporting guidelines do not orient on reporting of contextual and implementation issues in sufficient detail. We therefore developed Programme Reporting Standards (PRS) to be used by SRMNCAH programme implementers and researchers. Read More

    Validity and reliability of a Malay version of the brief illness perception questionnaire for patients with type 2 diabetes mellitus.
    BMC Med Res Methodol 2017 Aug 3;17(1):118. Epub 2017 Aug 3.
    Julius Center for Health Sciences and Primary Care, Department of General Practice, University Medical Center Utrecht, Huispost Str.6.131, P.O. Box 85500, 3508, GA, Utrecht, The Netherlands.
    Background: Illness perceptions involve the personal beliefs that patients have about their illness and may influence health behaviours considerably. Since an instrument to measure these perceptions for Malay population in Malaysia is lacking, we translated and examined the psychometric properties of the Malay version of the Brief Illness Perception Questionnaire (MBIPQ) in adult patients with type 2 diabetes mellitus.

    Methods: The MBIPQ has nine items, all use a 0-10 response scale, except the ninth item about causal factors, which is an open-ended item. Read More

    A mega-ethnography of eleven qualitative evidence syntheses exploring the experience of living with chronic non-malignant pain.
    BMC Med Res Methodol 2017 Aug 1;17(1):116. Epub 2017 Aug 1.
    Nuffield Orthopaedic Centre, Oxford University Hospitals NHS Foundation Trust, Oxford, UK.
    Background: Each year over five million people develop chronic non-malignant pain and can experience healthcare as an adversarial struggle. The aims of this study were: (1) to bring together qualitative evidence syntheses that explore patients' experience of living with chronic non-malignant pain and develop conceptual understanding of what it is like to live with chronic non-malignant pain for improved healthcare; (2) to undertake the first mega-ethnography of qualitative evidence syntheses using the methods of meta-ethnography.

    Methods: We used the seven stages of meta-ethnography refined for large studies. Read More

    A comparison of the conditional inference survival forest model to random survival forests based on a simulation study as well as on two applications with time-to-event data.
    BMC Med Res Methodol 2017 Jul 28;17(1):115. Epub 2017 Jul 28.
    Division of Epidemiology and Biostatistics, School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa.
    Background: Random survival forest (RSF) models have been identified as alternative methods to the Cox proportional hazards model in analysing time-to-event data. These methods, however, have been criticised for the bias that results from favouring covariates with many split-points and hence conditional inference forests for time-to-event data have been suggested. Conditional inference forests (CIF) are known to correct the bias in RSF models by separating the procedure for the best covariate to split on from that of the best split point search for the selected covariate. Read More

    A comparison of multiple imputation methods for handling missing values in longitudinal data in the presence of a time-varying covariate with a non-linear association with time: a simulation study.
    BMC Med Res Methodol 2017 Jul 25;17(1):114. Epub 2017 Jul 25.
    Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, VIC, Australia.
    Background: Missing data is a common problem in epidemiological studies, and is particularly prominent in longitudinal data, which involve multiple waves of data collection. Traditional multiple imputation (MI) methods (fully conditional specification (FCS) and multivariate normal imputation (MVNI)) treat repeated measurements of the same time-dependent variable as just another 'distinct' variable for imputation and therefore do not make the most of the longitudinal structure of the data. Only a few studies have explored extensions to the standard approaches to account for the temporal structure of longitudinal data. Read More

    Implementing the EffTox dose-finding design in the Matchpoint trial.
    BMC Med Res Methodol 2017 Jul 20;17(1):112. Epub 2017 Jul 20.
    Cancer Research UK Clinical Trials Unit, Institute of Cancer & Genomic Sciences, University of Birmingham, Birmingham, B15 2TT, UK.
    Background: The Matchpoint trial aims to identify the optimal dose of ponatinib to give with conventional chemotherapy consisting of fludarabine, cytarabine and idarubicin to chronic myeloid leukaemia patients in blastic transformation phase. The dose should be both tolerable and efficacious. This paper describes our experience implementing EffTox in the Matchpoint trial. Read More

    Basic parametric analysis for a multi-state model in hospital epidemiology.
    BMC Med Res Methodol 2017 Jul 20;17(1):111. Epub 2017 Jul 20.
    Institute for Medical Biometry and Statistics, Faculty of Medicine and Medical Center - University of Freiburg, Stefan-Meier Str. 26, Freiburg, 79104, Germany.
    Background: The extended illness-death model is a useful tool to study the risks and consequences of hospital-acquired infections (HAIs). The statistical quantities of interest are the transition-specific hazard rates and the transition probabilities as well as attributable mortality (AM) and the population-attributable fraction (PAF). In the most general case calculation of these expressions is mathematically complex. Read More

    Integrating data from randomized controlled trials and observational studies to predict the response to pregabalin in patients with painful diabetic peripheral neuropathy.
    BMC Med Res Methodol 2017 Jul 20;17(1):113. Epub 2017 Jul 20.
    Pfizer Inc, 235 E 42nd St, New York, NY, 10017, USA.
    Background: More patient-specific medical care is expected as more is learned about variations in patient responses to medical treatments. Analytical tools enable insights by linking treatment responses from different types of studies, such as randomized controlled trials (RCTs) and observational studies. Given the importance of evidence from both types of studies, our goal was to integrate these types of data into a single predictive platform to help predict response to pregabalin in individual patients with painful diabetic peripheral neuropathy (pDPN). Read More

    Binomial outcomes in dataset with some clusters of size two: can the dependence of twins be accounted for? A simulation study comparing the reliability of statistical methods based on a dataset of preterm infants.
    BMC Med Res Methodol 2017 Jul 20;17(1):110. Epub 2017 Jul 20.
    Division of Health and Social Care Research King's College London and NIHR Biomedical Research Centre at Guy's and St Thomas' NHS Foundation Trust and King's College London, London, UK.
    Background: The analysis of perinatal outcomes often involves datasets with some multiple births. These are datasets mostly formed of independent observations and a limited number of clusters of size two (twins) and maybe of size three or more. This non-independence needs to be accounted for in the statistical analysis. Read More

    A random effects meta-analysis model with Box-Cox transformation.
    BMC Med Res Methodol 2017 Jul 19;17(1):109. Epub 2017 Jul 19.
    Research Institute for Primary Care and Health Sciences, Keele University, Staffordshire, ST5 5BG, UK.
    Background: In a random effects meta-analysis model, true treatment effects for each study are routinely assumed to follow a normal distribution. However, normality is a restrictive assumption and the misspecification of the random effects distribution may result in a misleading estimate of overall mean for the treatment effect, an inappropriate quantification of heterogeneity across studies and a wrongly symmetric prediction interval.

    Methods: We focus on problems caused by an inappropriate normality assumption of the random effects distribution, and propose a novel random effects meta-analysis model where a Box-Cox transformation is applied to the observed treatment effect estimates. Read More

    A literature review of applied adaptive design methodology within the field of oncology in randomised controlled trials and a proposed extension to the CONSORT guidelines.
    BMC Med Res Methodol 2017 Jul 18;17(1):108. Epub 2017 Jul 18.
    Warwick Clinical Trials Unit, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK.
    Background: The application of adaptive design methodology within a clinical trial setting is becoming increasingly popular. However the application of these methods within trials is not being reported as adaptive designs hence making it more difficult to capture the emerging use of these designs. Within this review, we aim to understand how adaptive design methodology is being reported, whether these methods are explicitly stated as an 'adaptive design' or if it has to be inferred and to identify whether these methods are applied prospectively or concurrently. Read More

    Nonlinear joint models for individual dynamic prediction of risk of death using Hamiltonian Monte Carlo: application to metastatic prostate cancer.
    BMC Med Res Methodol 2017 Jul 17;17(1):105. Epub 2017 Jul 17.
    IAME, UMR 1137, INSERM, Université Paris Diderot, Sorbonne Paris Cité, 16, rue Henri Huchard, Paris, 75018, France.
    Background: Joint models of longitudinal and time-to-event data are increasingly used to perform individual dynamic prediction of a risk of event. However the difficulty to perform inference in nonlinear models and to calculate the distribution of individual parameters has long limited this approach to linear mixed-effect models for the longitudinal part. Here we use a Bayesian algorithm and a nonlinear joint model to calculate individual dynamic predictions. Read More

    Protocol adherence for continuously titrated interventions in randomized trials: an overview of the current methodology and case study.
    BMC Med Res Methodol 2017 Jul 17;17(1):106. Epub 2017 Jul 17.
    Department of Medicine, Université de Sherbrooke, Sherbrooke, Québec, Canada.
    Background: The standard definition for protocol adherence is the proportion of all scheduled doses that are delivered. In clinical research, this definition has several limitations when evaluating protocol adherence in trials that study interventions requiring continuous titration.

    Discussion: Building upon a specific case study, we analyzed a recent trial of a continuously titrated intervention to assess the impact of different definitions of protocol deviations on the interpretation of protocol adherence. Read More

    Clarifying the distinction between case series and cohort studies in systematic reviews of comparative studies: potential impact on body of evidence and workload.
    BMC Med Res Methodol 2017 Jul 17;17(1):107. Epub 2017 Jul 17.
    Institute for Research in Operative Medicine, Chair of Surgical Research, Faculty of Health, School of Medicine, Witten/Herdecke University, Ostmerheimer Str. 200, 51109, Cologne, Germany.
    Distinguishing cohort studies from case series is difficult.We propose a conceptualization of cohort studies in systematic reviews of comparative studies. The main aim of this conceptualization is to clarify the distinction between cohort studies and case series. Read More

    Using structural equation modeling for network meta-analysis.
    BMC Med Res Methodol 2017 Jul 14;17(1):104. Epub 2017 Jul 14.
    Department of Public Health and Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, Taipei, Taiwan.
    Background: Network meta-analysis overcomes the limitations of traditional pair-wise meta-analysis by incorporating all available evidence into a general statistical framework for simultaneous comparisons of several treatments. Currently, network meta-analyses are undertaken either within the Bayesian hierarchical linear models or frequentist generalized linear mixed models. Structural equation modeling (SEM) is a statistical method originally developed for modeling causal relations among observed and latent variables. Read More

    Accounting for treatment use when validating a prognostic model: a simulation study.
    BMC Med Res Methodol 2017 Jul 14;17(1):103. Epub 2017 Jul 14.
    Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, PO Box 85500, 3508, GA, Utrecht, the Netherlands.
    Background: Prognostic models often show poor performance when applied to independent validation data sets. We illustrate how treatment use in a validation set can affect measures of model performance and present the uses and limitations of available analytical methods to account for this using simulated data.

    Methods: We outline how the use of risk-lowering treatments in a validation set can lead to an apparent overestimation of risk by a prognostic model that was developed in a treatment-naïve cohort to make predictions of risk without treatment. Read More

    Cost and yield considerations when expanding recruitment for genetic studies: the primary open-angle African American glaucoma genetics study.
    BMC Med Res Methodol 2017 Jul 14;17(1):101. Epub 2017 Jul 14.
    Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA.
    Background: African Americans have been historically under-represented in genetic studies. More research is needed on effective recruitment strategies for this population, especially on approaches that supplement traditional clinic enrollment. This study evaluates the cost and efficacy of four supplemental recruitment methods employed by the Primary Open-Angle African American Glaucoma Genetics (POAAGG) study. Read More

    Sample size re-estimation in paired comparative diagnostic accuracy studies with a binary response.
    BMC Med Res Methodol 2017 Jul 14;17(1):102. Epub 2017 Jul 14.
    Institute of Primary Care and Health Sciences, Keele University, David Weatherall Building, Stoke-on-Trent, ST5 5BG, UK.
    Background: The sample size required to power a study to a nominal level in a paired comparative diagnostic accuracy study, i.e. studies in which the diagnostic accuracy of two testing procedures is compared relative to a gold standard, depends on the conditional dependence between the two tests - the lower the dependence the greater the sample size required. Read More

    Implementation fidelity of a self-management course for epilepsy: method and assessment.
    BMC Med Res Methodol 2017 Jul 11;17(1):100. Epub 2017 Jul 11.
    King's College London, Institute of Psychiatry, Psychology and Neuroscience, De Crespigny Park, London, SE5 8AF, UK.
    Background: Complex interventions such as self-management courses are difficult to evaluate due to the many interacting components. The way complex interventions are delivered can influence the effect they have for patients, and can impact the interpretation of outcomes of clinical trials. Implementation fidelity evaluates whether complex interventions are delivered according to protocol. Read More

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