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BMC Medical Research Methodology

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https://www.readbyqxmd.com/read/28494765/duration-of-the-common-cold-and-similar-continuous-outcomes-should-be-analyzed-on-the-relative-scale-a-case-study-of-two-zinc-lozenge-trials
#1
Harri Hemilä
BACKGROUND: The relative scale has been used for decades in analysing binary data in epidemiology. In contrast, there has been a long tradition of carrying out meta-analyses of continuous outcomes on the absolute, original measurement, scale. The biological rationale for using the relative scale in the analysis of binary outcomes is that it adjusts for baseline variations; however, similar baseline variations can occur in continuous outcomes and relative effect scale may therefore be often useful also for continuous outcomes...
May 12, 2017: BMC Medical Research Methodology
https://www.readbyqxmd.com/read/28486955/changes-in-affect-after-completing-a-mailed-survey-about-trauma-two-pre-and-post-test-studies-in-former-disability-applicants-for-posttraumatic-stress-disorder
#2
Maureen Murdoch, Shannon Marie Kehle-Forbes, Melissa Ruth Partin
BACKGROUND: One potential concern with using mailed surveys containing trauma-related content is the possibility of re-traumatizing survivors without a trained mental health professional present. Prior research provides insufficient guidance regarding the prevalence and magnitude of this risk because the psychological harms of trauma-related surveys have typically been estimated using single post-test observations. Post-test observations cannot quantify magnitude of change in participants' emotional states and may over or under estimate associations between participants' characteristics (risk factors) and post-survey upset...
May 10, 2017: BMC Medical Research Methodology
https://www.readbyqxmd.com/read/28482809/on-the-impact-of-nonresponse-in-logistic-regression-application-to-the-45-and-up-study
#3
Joanna J J Wang, Mark Bartlett, Louise Ryan
BACKGROUND: In longitudinal studies, nonresponse to follow-up surveys poses a major threat to validity, interpretability and generalisation of results. The problem of nonresponse is further complicated by the possibility that nonresponse may depend on the outcome of interest. We identified sociodemographic, general health and wellbeing characteristics associated with nonresponse to the follow-up questionnaire and assessed the extent and effect of nonresponse on statistical inference in a large-scale population cohort study...
May 8, 2017: BMC Medical Research Methodology
https://www.readbyqxmd.com/read/28464839/on-comparison-of-net-survival-curves
#4
Klemen Pavlič, Maja Pohar Perme
BACKGROUND: Relative survival analysis is a subfield of survival analysis where competing risks data are observed, but the causes of death are unknown. A first step in the analysis of such data is usually the estimation of a net survival curve, possibly followed by regression modelling. Recently, a log-rank type test for comparison of net survival curves has been introduced and the goal of this paper is to explore its properties and put this methodological advance into the context of the field...
May 2, 2017: BMC Medical Research Methodology
https://www.readbyqxmd.com/read/28454568/double-adjustment-in-propensity-score-matching-analysis-choosing-a-threshold-for-considering-residual-imbalance
#5
Tri-Long Nguyen, Gary S Collins, Jessica Spence, Jean-Pierre Daurès, P J Devereaux, Paul Landais, Yannick Le Manach
BACKGROUND: Double-adjustment can be used to remove confounding if imbalance exists after propensity score (PS) matching. However, it is not always possible to include all covariates in adjustment. We aimed to find the optimal imbalance threshold for entering covariates into regression. METHODS: We conducted a series of Monte Carlo simulations on virtual populations of 5,000 subjects. We performed PS 1:1 nearest-neighbor matching on each sample. We calculated standardized mean differences across groups to detect any remaining imbalance in the matched samples...
April 28, 2017: BMC Medical Research Methodology
https://www.readbyqxmd.com/read/28446140/measurement-properties-of-the-danish-version-of-the-awareness-and-beliefs-about-cancer-abc-measure
#6
Line Hvidberg, Anette Fischer Pedersen, Christian Nielsen Wulff, Anders Helles Carlsen, Peter Vedsted
BACKGROUND: The International Cancer Benchmarking Partnership aims to study international differences in cancer survival and the possible causes. Participating countries are Australia, Canada, Norway, Sweden, Denmark and the UK and a particular focus area is differences in awareness and beliefs about cancer. In this connection, the Awareness and Beliefs about Cancer (ABC) measure has been translated into multiple languages. The aim of this study is to appraise the translation process and measurement properties of the Danish version of the ABC measure...
April 26, 2017: BMC Medical Research Methodology
https://www.readbyqxmd.com/read/28446138/assessing-the-complexity-of-interventions-within-systematic-reviews-development-content-and-use-of-a-new-tool-icat_sr
#7
Simon Lewin, Maggie Hendry, Jackie Chandler, Andrew D Oxman, Susan Michie, Sasha Shepperd, Barnaby C Reeves, Peter Tugwell, Karin Hannes, Eva A Rehfuess, Vivien Welch, Joanne E Mckenzie, Belinda Burford, Jennifer Petkovic, Laurie M Anderson, Janet Harris, Jane Noyes
BACKGROUND: Health interventions fall along a spectrum from simple to more complex. There is wide interest in methods for reviewing 'complex interventions', but few transparent approaches for assessing intervention complexity in systematic reviews. Such assessments may assist review authors in, for example, systematically describing interventions and developing logic models. This paper describes the development and application of the intervention Complexity Assessment Tool for Systematic Reviews (iCAT_SR), a new tool to assess and categorise levels of intervention complexity in systematic reviews...
April 26, 2017: BMC Medical Research Methodology
https://www.readbyqxmd.com/read/28446131/the-effectiveness-of-a-monetary-incentive-offer-on-survey-response-rates-and-response-completeness-in-a-longitudinal-study
#8
Shengchao Yu, Howard E Alper, Angela-Maithy Nguyen, Robert M Brackbill, Lennon Turner, Deborah J Walker, Carey B Maslow, Kimberly C Zweig
BACKGROUND: Achieving adequate response rates is an ongoing challenge for longitudinal studies. The World Trade Center Health Registry is a longitudinal health study that periodically surveys a cohort of ~71,000 people exposed to the 9/11 terrorist attacks in New York City. Since Wave 1, the Registry has conducted three follow-up surveys (Waves 2-4) every 3-4 years and utilized various strategies to increase survey participation. A promised monetary incentive was offered for the first time to survey non-respondents in the recent Wave 4 survey, conducted 13-14 years after 9/11...
April 26, 2017: BMC Medical Research Methodology
https://www.readbyqxmd.com/read/28446127/sample-size-and-power-determination-when-limited-preliminary-information-is-available
#9
Christine E McLaren, Wen-Pin Chen, Thomas D O'Sullivan, Daniel L Gillen, Min-Ying Su, Jeon H Chen, Bruce J Tromberg
BACKGROUND: We describe a novel strategy for power and sample size determination developed for studies utilizing investigational technologies with limited available preliminary data, specifically of imaging biomarkers. We evaluated diffuse optical spectroscopic imaging (DOSI), an experimental noninvasive imaging technique that may be capable of assessing changes in mammographic density. Because there is significant evidence that tamoxifen treatment is more effective at reducing breast cancer risk when accompanied by a reduction of breast density, we designed a study to assess the changes from baseline in DOSI imaging biomarkers that may reflect fluctuations in breast density in premenopausal women receiving tamoxifen...
April 26, 2017: BMC Medical Research Methodology
https://www.readbyqxmd.com/read/28441932/an-experimental-comparison-of-web-push-vs-paper-only-survey-procedures-for-conducting-an-in-depth-health-survey-of-military-spouses
#10
Hope Seib McMaster, Cynthia A LeardMann, Steven Speigle, Don A Dillman
BACKGROUND: Previous research has found that a "web-push" approach to data collection, which involves contacting people by mail to request an Internet survey response while withholding a paper response option until later in the contact process, consistently achieves lower response rates than a "paper-only" approach, whereby all respondents are contacted and requested to respond by mail. METHOD: An experiment was designed, as part of the Millennium Cohort Family Study, to compare response rates, sample representativeness, and cost between a web-push and a paper-only approach; each approach comprised 3 stages of mail contacts...
April 26, 2017: BMC Medical Research Methodology
https://www.readbyqxmd.com/read/28431517/sharp-bounds-on-sufficient-cause-interactions-under-the-assumption-of-no-redundancy
#11
Wen-Chung Lee
BACKGROUND: Sufficient-cause interaction is a type of interaction that has received much attention recently. The sufficient component cause model on which the sufficient-cause interaction is based is however a non-identifiable model. Estimating the interaction parameters from the model is mathematically impossible. METHODS: In this paper, I derive bounding formulae for sufficient-cause interactions under the assumption of no redundancy. RESULTS: Two real data sets are used to demonstrate the method (R codes provided)...
April 21, 2017: BMC Medical Research Methodology
https://www.readbyqxmd.com/read/28431516/evaluation-of-the-impact-of-disease-prevention-measures-a-methodological-note-on-defining-incidence-rates
#12
Yin-Bun Cheung, Ying Xu, Matthew Cairns, Paul Milligan
BACKGROUND: In studies of recurrent events, it is common to consider a person who has suffered a disease episode and received curative treatment to be not at risk of suffering a new episode for a duration of time. It is a common practice to deduct this duration from the person's observation time in the statistical analysis of the incidence data. METHODS: We examined the concepts of incidence and protective efficacy from a real life point of view. We developed simple formulae to show the relationship between the incidence rate and protective efficacy between analyses with and without deducting the curative treatment time from the observation time...
April 21, 2017: BMC Medical Research Methodology
https://www.readbyqxmd.com/read/28431505/using-evaluability-assessment-to-assess-local-community-development-health-programmes-a-scottish-case-study
#13
Melissa Belford, Tony Robertson, Ruth Jepson
BACKGROUND: Evaluation of the potential effectiveness of a programme's objectives (health or otherwise) is important in demonstrating how programmes work. However, evaluations are expensive and can focus on unrealistic outcomes not grounded in strong theory, especially where there is pressure to show effectiveness. The aim of this research was to demonstrate that the evaluability assessment (a cost-effective pre-evaluation tool that primarily gives quick, constructive feedback) can be used to help develop programme and outcome objectives to improve programmes while they run and to assist in producing more effective evaluations...
April 21, 2017: BMC Medical Research Methodology
https://www.readbyqxmd.com/read/28427353/assessing-the-impact-of-natural-policy-experiments-on-socioeconomic-inequalities-in-health-how-to-apply-commonly-used-quantitative-analytical-methods
#14
Yannan Hu, Frank J van Lenthe, Rasmus Hoffmann, Karen van Hedel, Johan P Mackenbach
BACKGROUND: The scientific evidence-base for policies to tackle health inequalities is limited. Natural policy experiments (NPE) have drawn increasing attention as a means to evaluating the effects of policies on health. Several analytical methods can be used to evaluate the outcomes of NPEs in terms of average population health, but it is unclear whether they can also be used to assess the outcomes of NPEs in terms of health inequalities. The aim of this study therefore was to assess whether, and to demonstrate how, a number of commonly used analytical methods for the evaluation of NPEs can be applied to quantify the effect of policies on health inequalities...
April 20, 2017: BMC Medical Research Methodology
https://www.readbyqxmd.com/read/28427350/evaluation-of-a-modified-version-of-the-posttraumatic-growth-inventory-short-form
#15
Navjot Kaur, Ben Porter, Cynthia A LeardMann, Laura E Tobin, Hector Lemus, David D Luxton
BACKGROUND: Posttraumatic growth is the positive change resulting from traumatic experiences and is typically assessed with retrospective measures like the Posttraumatic Growth Inventory (PTGI). The PTGI was designed to include reference to a specific traumatic event, making it difficult to implement, without change, in prospective survey studies. Thus, a modified Posttraumatic Growth Inventory-Short Form (PTGI-SF) was included in a large prospective study of current and former U.S. military personnel...
April 20, 2017: BMC Medical Research Methodology
https://www.readbyqxmd.com/read/28427340/does-the-association-between-adherence-to-statin-medications-and-mortality-depend-on-measurement-approach-a-retrospective-cohort-study
#16
Mhd Wasem Alsabbagh, Dean Eurich, Lisa M Lix, Thomas W Wilson, David F Blackburn
BACKGROUND: The aim of this study was to examine the relationship between mortality and statin adherence using two different approaches to adherence measurement (summary versus repeated-measures). METHODS: A retrospective cohort study was conducted using administrative data from Saskatchewan, Canada between 1994 and 2008. Eligible individuals received a prescription for a statin following hospitalization for acute coronary syndrome (ACS). Adherence was measured using proportion of days covered (PDC) expressed either as: 1) a fixed summary measure, or 2) as a repeatedly measured covariate...
April 20, 2017: BMC Medical Research Methodology
https://www.readbyqxmd.com/read/28427337/treatment-seeking-behaviour-in-low-and-middle-income-countries-estimated-using-a-bayesian-model
#17
Victor A Alegana, Jim Wright, Carla Pezzulo, Andrew J Tatem, Peter M Atkinson
BACKGROUND: Seeking treatment in formal healthcare for uncomplicated infections is vital to combating disease in low- and middle-income countries (LMICs). Healthcare treatment-seeking behaviour varies within and between communities and is modified by socio-economic, demographic, and physical factors. As a result, it remains a challenge to quantify healthcare treatment-seeking behaviour using a metric that is comparable across communities. Here, we present an application for transforming individual categorical responses (actions related to fever) to a continuous probabilistic estimate of fever treatment for one country in Sub-Saharan Africa (SSA)...
April 20, 2017: BMC Medical Research Methodology
https://www.readbyqxmd.com/read/28427334/the-impact-of-the-mode-of-survey-administration-on-estimates-of-daily-smoking-for-mobile-phone-only-users
#18
Joseph Hanna, Damien V Cordery, David G Steel, Walter Davis, Timothy C Harrold
BACKGROUND: Over the past decade, there have been substantial changes in landline and mobile phone ownership, with a substantial increase in the proportion of mobile-only households. Estimates of daily smoking rates for the mobile phone only (MPO) population have been found to be substantially higher than the rest of the population and telephone surveys that use a dual sampling frame (landline and mobile phones) are now considered best practice. Smoking is seen as an undesirable behaviour; measuring such behaviours using an interviewer may lead to lower estimates when using telephone based surveys compared to self-administered approaches...
April 20, 2017: BMC Medical Research Methodology
https://www.readbyqxmd.com/read/28420349/grey-literature-in-systematic-reviews-a-cross-sectional-study-of-the-contribution-of-non-english-reports-unpublished-studies-and-dissertations-to-the-results-of-meta-analyses-in-child-relevant-reviews
#19
Lisa Hartling, Robin Featherstone, Megan Nuspl, Kassi Shave, Donna M Dryden, Ben Vandermeer
BACKGROUND: Systematic reviews (SRs) are an important source of information about healthcare interventions. A key component of a well-conducted SR is a comprehensive literature search. There is limited evidence on the contribution of non-English reports, unpublished studies, and dissertations and their impact on results of meta-analyses. METHODS: Our sample included SRs from three Cochrane Review Groups: Acute Respiratory Infections (ARI), Infectious Diseases (ID), Developmental Psychosocial and Learning Problems (DPLP) (n = 129)...
April 19, 2017: BMC Medical Research Methodology
https://www.readbyqxmd.com/read/28420347/kappa-statistic-to-measure-agreement-beyond-chance-in-free-response-assessments
#20
Marc Carpentier, Christophe Combescure, Laura Merlini, Thomas V Perneger
BACKGROUND: The usual kappa statistic requires that all observations be enumerated. However, in free-response assessments, only positive (or abnormal) findings are notified, but negative (or normal) findings are not. This situation occurs frequently in imaging or other diagnostic studies. We propose here a kappa statistic that is suitable for free-response assessments. METHOD: We derived the equivalent of Cohen's kappa statistic for two raters under the assumption that the number of possible findings for any given patient is very large, as well as a formula for sampling variance that is applicable to independent observations (for clustered observations, a bootstrap procedure is proposed)...
April 19, 2017: BMC Medical Research Methodology
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