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BMC Medical Research Methodology

Joaquín Moncho, Pamela Pereyra-Zamora, Nayara Tamayo-Fonseca, Manuel Giron, Manuel Gómez-Beneyto, Andreu Nolasco
BACKGROUND: We explored the impact of 2008 recession on the prevalence of mental health problems in Spain. METHODS: Repeated cross-sectional survey design. Datasets from 2006 and 2011 were used, and temporal change was examined. The study was conducted on the economically active population (16-64 years old). The two surveys included 29,478 and 21,007 people, obtaining a 96 and 89.6% response rate, respectively. Multiple logistic regression models were adjusted to identify poor mental health risk factors...
July 13, 2018: BMC Medical Research Methodology
Jeffrey Gu, Gary Groot
BACKGROUND: Clinical medicine has lagged behind other fields in understanding and utilizing frameworks to guide research. In this article, we introduce a new framework to examine why women choose mastectomy versus breast conserving therapy in early stage breast cancer, and highlight the importance of utilizing a conceptual framework to guide clinical research. METHODS: The framework we present was developed through integrating previous literature, frameworks, theories, models, and the author's past research...
July 9, 2018: BMC Medical Research Methodology
Helene Karcher, Shuai Fu, Jie Meng, Mikkel Zöllner Ankarfeldt, Orestis Efthimiou, Mark Belger, Josep Maria Haro, Lucien Abenhaim, Clementine Nordon
BACKGROUND: Phase III randomized controlled trials (RCT) typically exclude certain patient subgroups, thereby potentially jeopardizing estimation of a drug's effects when prescribed to wider populations and under routine care ("effectiveness"). Conversely, enrolling heterogeneous populations in RCTs can increase endpoint variability and compromise detection of a drug's effect. We developed the "RCT augmentation" method to quantitatively support RCT design in the identification of exclusion criteria to relax to address both of these considerations...
July 6, 2018: BMC Medical Research Methodology
Thomas J Glorioso, Gary K Grunwald, P Michael Ho, Thomas M Maddox
BACKGROUND: Multilevel models for non-normal outcomes are widely used in medical and health sciences research. While methods for interpreting fixed effects are well-developed, methods to quantify and interpret random cluster variation and compare it with other sources of variation are less established. Random cluster variation, sometimes referred to as general contextual effects (GCE), may be the main focus of a study; therefore, easily interpretable methods are needed to quantify GCE...
July 6, 2018: BMC Medical Research Methodology
Holly Tibble, Hsei Di Law, Matthew J Spittal, Rosemary Karmel, Rohan Borschmann, Katie Hail-Jares, Laura A Thomas, Stuart A Kinner
BACKGROUND: Records pertaining to individuals whose identity cannot be verified with legal documentation may contain errors, or be incorrect by intention of the individual. Probabilistic data linkage, especially in vulnerable populations where the incidence of such records may be higher, must be considerate of the usage of these records. METHODS: A data linkage was conducted between Queensland Youth Justice records and the Australian National Death Index. Links were assessed to determine how often they were made using the unverified (alias) records that would not have been made in their absence (i...
July 6, 2018: BMC Medical Research Methodology
Benjamin M Davies, Samuel Goh, Keonwoo Yi, Isla Kuhn, Mark R N Kotter
BACKGROUND: Degenerative cervical myelopathy (DCM) is a common condition with many unmet clinical needs. Pooled analysis of studies is an important tool for advancing medical understanding. This process starts with a systematic search of the literature. Identification of studies in DCM is challenged by a number of factors, including non-specific terminology and index terms. Search filters or HEDGEs, are search strings developed and validated to optimise medical literature searches. We aimed to develop a search filter for DCM for the MEDLINE database...
July 6, 2018: BMC Medical Research Methodology
Justin S Merkow, Janine M Hoerauf, Angela F Moss, Jason Brainard, Lena M Mayes, Ana Fernandez-Bustamante, Susan K Mikulich-Gilbertson, Karsten Bartels
BACKGROUND: Limited translational success in critical care medicine is thought to be in part due to inadequate methodology, study design, and reporting in preclinical studies. The purpose of this study was to compare reporting of core features of experimental rigor: blinding, randomization, and power calculations in critical care medicine animal experimental research. We hypothesized that these study design characteristics were more frequently reported in 2015 versus 2005. METHODS: We performed an observational bibliometric study to grade manuscripts on blinding, randomization, and power calculations...
July 5, 2018: BMC Medical Research Methodology
C Rotejanaprasert, A Lawson, H Rossow, J Sane, O Huitu, H Henttonen, V J Del Rio Vilas
BACKGROUND: There are an increasing number of geo-coded information streams available which could improve public health surveillance accuracy and efficiency when properly integrated. Specifically, for zoonotic diseases, knowledge of spatial and temporal patterns of animal host distribution can be used to raise awareness of human risk and enhance early prediction accuracy of human incidence. METHODS: To this end, we develop a spatiotemporal joint modeling framework to integrate human case data and animal host data to offer a modeling alternative for combining multiple surveillance data streams in a novel way...
July 5, 2018: BMC Medical Research Methodology
Ilyas Bakbergenuly, Elena Kulinskaya
BACKGROUND: Systematic reviews and meta-analyses of binary outcomes are widespread in all areas of application. The odds ratio, in particular, is by far the most popular effect measure. However, the standard meta-analysis of odds ratios using a random-effects model has a number of potential problems. An attractive alternative approach for the meta-analysis of binary outcomes uses a class of generalized linear mixed models (GLMMs). GLMMs are believed to overcome the problems of the standard random-effects model because they use a correct binomial-normal likelihood...
July 4, 2018: BMC Medical Research Methodology
María Abad-Arranz, Ana Moran-Rodríguez, Enrique Mascarós Balaguer, Carmen Quintana Velasco, Laura Abad Polo, Sara Núñez Palomo, Jaime Gonzálvez Rey, Ana María Fernández Vargas, Antonio Hidalgo Requena, Jose Manuel Helguera Quevedo, Marina García Pardo, Jose Luis Lopez-Campos
BACKGROUND: A thorough evaluation of the adequacy of clinical practice in a designated health care setting and temporal context is key for clinical care improvement. This study aimed to perform a clinical audit of primary care to evaluate clinical care delivered to patients with COPD in routine clinical practice. METHODS: The Community Assessment of COPD Health Care (COACH) study was an observational, multicenter, nationwide, non-interventional, retrospective, clinical audit of randomly selected primary care centers in Spain...
July 3, 2018: BMC Medical Research Methodology
Annie M Racine, Yun Gou, Tamara G Fong, Edward R Marcantonio, Eva M Schmitt, Thomas G Travison, Sharon K Inouye, Richard N Jones
BACKGROUND: Few studies have compared methods to correct for retest effects or practice effects in settings where an acute event could influence test performance, such as major surgery. Our goal in this study was to evaluate the use of different methods to correct for the effects of practice or retest on repeated test administration in the context of an observational study of older adults undergoing elective surgery. METHODS: In a cohort of older surgical patients (N = 560) and a non-surgical comparison group (N = 118), we compared changes on repeated cognitive testing using a summary measure of general cognitive performance (GCP) between patients who developed post-operative delirium and those who did not...
July 3, 2018: BMC Medical Research Methodology
Vahé Asvatourian, Clélia Coutzac, Nathalie Chaput, Caroline Robert, Stefan Michiels, Emilie Lanoy
BACKGROUND: Recently, the intervention calculus when the DAG is absent (IDA) method was developed to estimate lower bounds of causal effects from observational high-dimensional data. Originally it was introduced to assess the effect of baseline biomarkers which do not vary over time. However, in many clinical settings, measurements of biomarkers are repeated at fixed time points during treatment and, therefore, this method needs to be extended. The purpose of this paper is to extend the first step of the IDA, the Peter Clarks (PC)-algorithm, to a time-dependent exposure in the context of a binary outcome...
July 3, 2018: BMC Medical Research Methodology
Susanne Schmitz, Áine Maguire, James Morris, Kai Ruggeri, Elisa Haller, Isla Kuhn, Joy Leahy, Natalia Homer, Ayesha Khan, Jack Bowden, Vanessa Buchanan, Michael O'Dwyer, Gordon Cook, Cathal Walsh
BACKGROUND: Network meta-analysis (NMA) allows for the estimation of comparative effectiveness of treatments that have not been studied in head-to-head trials; however, relative treatment effects for all interventions can only be derived where available evidence forms a connected network. Head-to-head evidence is limited in many disease areas, regularly resulting in disconnected evidence structures where a large number of treatments are available. This is also the case in the evidence of treatments for relapsed or refractory multiple myeloma...
June 28, 2018: BMC Medical Research Methodology
Oliver T Stirrup, David T Dunn
BACKGROUND: Minimisation of the delay to diagnosis is critical to achieving optimal outcomes for HIV patients and to limiting the potential for further onward infections. However, investigation of diagnosis delay is hampered by the fact that in most newly diagnosed patients the exact timing of infection cannot be determined and so inferences must be drawn from biomarker data. METHODS: We develop a Bayesian statistical model to evaluate delay-to-diagnosis distributions in HIV patients without known infection date, based on viral sequence genetic diversity and longitudinal viral load and CD4 count data...
June 27, 2018: BMC Medical Research Methodology
Anna Rudvik, Marianne Månsson
BACKGROUND: Impaired insulin sensitivity is a key abnormality underlying the development of type 2 diabetes. Measuring insulin sensitivity is therefore of importance in identifying individuals at risk of developing diabetes and for the evaluation of diabetes-focused interventions. A number of measures have been proposed for this purpose. Among these the hyperinsulinemic euglycemic clamp (HEC) is considered the gold standard. However, as the HEC is a costly, time consuming and invasive method requiring trained staff, there is a need for simpler so called surrogate measures...
June 26, 2018: BMC Medical Research Methodology
Wansu Chen, Lei Qian, Jiaxiao Shi, Meredith Franklin
BACKGROUND: Log-binomial and robust (modified) Poisson regression models are popular approaches to estimate risk ratios for binary response variables. Previous studies have shown that comparatively they produce similar point estimates and standard errors. However, their performance under model misspecification is poorly understood. METHODS: In this simulation study, the statistical performance of the two models was compared when the log link function was misspecified or the response depended on predictors through a non-linear relationship (i...
June 22, 2018: BMC Medical Research Methodology
Catharina G M Groothuis-Oudshoorn, Edwin R van den Heuvel, Paul F M Krabbe
BACKGROUND: A new patient-reported health measurement model has been developed to quantify descriptions of health states. Known as the multi-attribute preference response (MAPR) model, it is based on item response theory. The response task in the MAPR is for a patient to judge whether hypothetical health-state descriptions are better or worse than his/her own health status. METHODS: In its most simple form MAPR is a Rasch model where for each respondent on the same unidimensional health scale values are estimated of their own health status and values of the hypothetical comparator health states...
June 22, 2018: BMC Medical Research Methodology
Babagnidé François Koladjo, Sylvie Escolano, Pascale Tubert-Bitter
BACKGROUND: In pharmacoepidemiology, the prescription preference-based instrumental variables (IV) are often used with linear models to solve the endogeneity due to unobserved confounders even when the outcome and the endogenous treatment are dichotomous variables. Using this instrumental variable, we proceed by Monte-Carlo simulations to compare the IV-based generalized method of moment (IV-GMM) and the two-stage residual inclusion (2SRI) method in this context. METHODS: We established the formula allowing us to compute the instrument's strength and the confounding level in the context of logistic regression models...
June 22, 2018: BMC Medical Research Methodology
Ivar Heuch, Safa Abdalla, Sally El Tayeb
BACKGROUND: Injuries represent an important cause of morbidity and mortality worldwide. In retrospective epidemiological studies, estimated rates of reported injuries often decline considerably when information is included from periods more than a few months before the data collection. Such low rates are usually regarded as a consequence of memory decay. It is largely unknown whether the extent of memory decay depends on external factors otherwise affecting injury rates. METHODS: A statistical model was introduced to separate the influence of external factors on true injury rates from effects on memory decay...
June 20, 2018: BMC Medical Research Methodology
Xiaochen Tai, Alanna M Smith, Allison J McGeer, Eve Dubé, Dorothy Linn Holness, Kevin Katz, Linda McGillis Hall, Shelly A McNeil, Jeff Powis, Brenda L Coleman
BACKGROUND: Web-based surveys have become increasingly popular but response rates are low and may be prone to selection bias. How people are invited to participate may impact response rates and needs further study as previous evidence is contradictory. The purpose of this study was to determine whether response to a web-based survey of healthcare workers would be higher with a posted or an emailed invitation. We also report results of the pilot study, which aims to estimate the percentage of adults vaccinated against influenza who report recurrent systemic adverse events (the same systemic adverse event occurring successively following receipt of influenza vaccines)...
June 20, 2018: BMC Medical Research Methodology
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