BMC Medical Research Methodology
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Published By Springer (Biomed Central Ltd.)

1471-2288, 1471-2288

2022 ◽  
Vol 22 (1) ◽  
Author(s):  
Gilma Hernández-Herrera ◽  
David Moriña ◽  
Albert Navarro

Abstract Background When dealing with recurrent events in observational studies it is common to include subjects who became at risk before follow-up. This phenomenon is known as left censoring, and simply ignoring these prior episodes can lead to biased and inefficient estimates. We aimed to propose a statistical method that performs well in this setting. Methods Our proposal was based on the use of models with specific baseline hazards. In this, the number of prior episodes were imputed when unknown and stratified according to whether the subject had been at risk of presenting the event before t = 0. A frailty term was also used. Two formulations were used for this “Specific Hazard Frailty Model Imputed” based on the “counting process” and “gap time.” Performance was then examined in different scenarios through a comprehensive simulation study. Results The proposed method performed well even when the percentage of subjects at risk before follow-up was very high. Biases were often below 10% and coverages were around 95%, being somewhat conservative. The gap time approach performed better with constant baseline hazards, whereas the counting process performed better with non-constant baseline hazards. Conclusions The use of common baseline methods is not advised when knowledge of prior episodes experienced by a participant is lacking. The approach in this study performed acceptably in most scenarios in which it was evaluated and should be considered an alternative in this context. It has been made freely available to interested researchers as R package miRecSurv.


2022 ◽  
Vol 22 (1) ◽  
Author(s):  
Sean Randall ◽  
Helen Wichmann ◽  
Adrian Brown ◽  
James Boyd ◽  
Tom Eitelhuber ◽  
...  

Abstract Background Privacy preserving record linkage (PPRL) methods using Bloom filters have shown promise for use in operational linkage settings. However real-world evaluations are required to confirm their suitability in practice. Methods An extract of records from the Western Australian (WA) Hospital Morbidity Data Collection 2011–2015 and WA Death Registrations 2011–2015 were encoded to Bloom filters, and then linked using privacy-preserving methods. Results were compared to a traditional, un-encoded linkage of the same datasets using the same blocking criteria to enable direct investigation of the comparison step. The encoded linkage was carried out in a blinded setting, where there was no access to un-encoded data or a ‘truth set’. Results The PPRL method using Bloom filters provided similar linkage quality to the traditional un-encoded linkage, with 99.3% of ‘groupings’ identical between privacy preserving and clear-text linkage. Conclusion The Bloom filter method appears suitable for use in situations where clear-text identifiers cannot be provided for linkage.


2022 ◽  
Vol 22 (1) ◽  
Author(s):  
Shabab Noor Islam ◽  
Tanvir Ahammed ◽  
Aniqua Anjum ◽  
Olayan Albalawi ◽  
Md. Jamal Uddin

Abstract Background Mendelian randomization (MR) studies using Genetic risk scores (GRS) as an instrumental variable (IV) have increasingly been used to control for unmeasured confounding in observational healthcare databases. However, proper reporting of methodological issues is sparse in these studies. We aimed to review published papers related to MR studies and identify reporting problems. Methods We conducted a systematic review using the clinical articles published between 2009 and 2019. We searched PubMed, Scopus, and Embase databases. We retrieved information from every MR study, including the tests performed to evaluate assumptions and the modelling approach used for estimation. Using our inclusion/exclusion criteria, finally, we identified 97 studies to conduct the review according to the PRISMA statement. Results Only 66 (68%) of the studies empirically verified the first assumption (Relevance assumption), and 40 (41.2%) studies reported the appropriate tests (e.g., R2, F-test) to investigate the association. A total of 35.1% clearly stated and discussed theoretical justifications for the second and third assumptions. 30.9% of the studies used a two-stage least square, and 11.3% used the Wald estimator method for estimating IV. Also, 44.3% of the studies conducted a sensitivity analysis to illuminate the robustness of estimates for violations of the untestable assumptions. Conclusions We found that incompleteness of the justification of the assumptions for the instrumental variable in MR studies was a common problem in our selected studies. This may misdirect the findings of the studies.


2022 ◽  
Vol 22 (1) ◽  
Author(s):  
Saeed Akhtar ◽  
Eisa Aldhafeeri ◽  
Farah Alshammari ◽  
Hana Jafar ◽  
Haya Malhas ◽  
...  

Abstract Background The aims of this cross-sectional study were to i) assess one-year period prevalence of one, two, three or more road traffic crashes (RTCs) as an ordinal outcome and ii) identify the drivers’ characteristics associated with this ordinal outcome among young adult drivers with propensity to recurrent RTCs in Kuwait. Methods During December 2016, 1465 students, 17 years old or older from 15 colleges of Kuwait University participated in this cross-sectional study. A self-administered questionnaire was used for data collection. One-year period prevalence (95% confidence interval (CI)) of one, two, three or more RTCs was computed. Multivariable proportional odds model was used to identify the drivers’ attributes associated with the ordinal outcome. Results One-year period prevalence (%) of one, two and three or more RTCs respectively was 23.1 (95% CI: 21.2, 25.6), 10.9 (95% CI: 9.4, 12.6), and 4.6 (95% CI: 3.6, 5.9). Participants were significantly (p < 0.05) more likely to be in higher RTCs count category than their current or lower RCTs count, if they habitually violated speed limit (adjusted proportional odds ratio (pORadjusted) = 1.40; 95% Cl: 1.13, 1.75), ran through red lights (pORadjusted = 1.64; 95%CI: 1.30, 2.06), frequently (≥ 3) received multiple (> 3) speeding tickets (pORadjusted = 1.63; 95% CI: 1.12, 2.38), frequently (> 10 times) violated no-parking zone during the past year (pORadjusted = 1.64; 95% CI: 1.06, 2.54) or being a patient with epilepsy (pORadjusted = 4.37; 95% CI: 1.63, 11.70). Conclusion High one-year period prevalence of one, two and three or more RTCs was recorded. Targeted education based on identified drivers’ attributes and stern enforcement of traffic laws may reduce the recurrent RTCs incidence in this and other similar populations in the region.


2022 ◽  
Vol 22 (1) ◽  
Author(s):  
Jingyu Cui ◽  
Jingwei Lu ◽  
Yijia Weng ◽  
Grace Y. Yi ◽  
Wenqing He

Abstract Background The coronavirus disease 2019 (COVID-19) pandemic has posed a significant influence on public mental health. Current efforts focus on alleviating the impacts of the disease on public health and the economy, with the psychological effects due to COVID-19 relatively ignored. In this research, we are interested in exploring the quantitative characterization of the pandemic impact on public mental health by studying an online survey dataset of the United States. Methods The analyses are conducted based on a large scale of online mental health-related survey study in the United States, conducted over 12 consecutive weeks from April 23, 2020 to July 21, 2020. We are interested in examining the risk factors that have a significant impact on mental health as well as in their estimated effects over time. We employ the multiple imputation by chained equations (MICE) method to deal with missing values and take logistic regression with the least absolute shrinkage and selection operator (Lasso) method to identify risk factors for mental health. Results Our analysis shows that risk predictors for an individual to experience mental health issues include the pandemic situation of the State where the individual resides, age, gender, race, marital status, health conditions, the number of household members, employment status, the level of confidence of the future food affordability, availability of health insurance, mortgage status, and the information of kids enrolling in school. The effects of most of the predictors seem to change over time though the degree varies for different risk factors. The effects of risk factors, such as States and gender show noticeable change over time, whereas the factor age exhibits seemingly unchanged effects over time. Conclusions The analysis results unveil evidence-based findings to identify the groups who are psychologically vulnerable to the COVID-19 pandemic. This study provides helpful evidence for assisting healthcare providers and policymakers to take steps for mitigating the pandemic effects on public mental health, especially in boosting public health care, improving public confidence in future food conditions, and creating more job opportunities. Trial registration This article does not report the results of a health care intervention on human participants.


2022 ◽  
Vol 22 (1) ◽  
Author(s):  
Azhar Farooqi ◽  
Karan Jutlla ◽  
Raghu Raghavan ◽  
Andrew Wilson ◽  
Mohammud Shams Uddin ◽  
...  

Abstract Background It is recognised that Black, Asian and Minority Ethnic (BAME) populations are generally underrepresented in research studies. The key objective of this work was to develop an evidence based, practical toolkit to help researchers maximise recruitment of BAME groups in research. Methods Development of the toolkit was an iterative process overseen by an expert steering group. Key steps included a detailed literature review, feedback from focus groups (including researchers and BAME community members) and further workshops and communication with participants to review the draft and final versions. Results Poor recruitment of BAME populations in research is due to complex reasons, these include factors such as inadequate attention to recruitment strategies and planning, poor engagement with communities and individuals due to issues such as cultural competency of researchers, historical poor experience of participating in research, and lack of links with community networks. Other factors include language issues, relevant expertise in research team and a lack of adequate resources that might be required in recruitment of BAME populations. Conclusions A toolkit was developed with key sections providing guidance on planning research and ensuring adequate engagement of communities and individuals. Together with sections suggesting how the research team can address training needs and adopt best practice. Researchers highlighted the issue of funding and how best to address BAME recruitment in grant applications, so a section on preparing a grant application was also included. The final toolkit document is practical, and includes examples of best practice and ‘top tips’ for researchers.


2022 ◽  
Vol 22 (1) ◽  
Author(s):  
Dai Su ◽  
Qinmengge Li ◽  
Tao Zhang ◽  
Philip Veliz ◽  
Yingchun Chen ◽  
...  

Abstract Background Early screening and accurately identifying Acute Appendicitis (AA) among patients with undifferentiated symptoms associated with appendicitis during their emergency visit will improve patient safety and health care quality. The aim of the study was to compare models that predict AA among patients with undifferentiated symptoms at emergency visits using both structured data and free-text data from a national survey. Methods We performed a secondary data analysis on the 2005-2017 United States National Hospital Ambulatory Medical Care Survey (NHAMCS) data to estimate the association between emergency department (ED) patients with the diagnosis of AA, and the demographic and clinical factors present at ED visits during a patient’s ED stay. We used binary logistic regression (LR) and random forest (RF) models incorporating natural language processing (NLP) to predict AA diagnosis among patients with undifferentiated symptoms. Results Among the 40,441 ED patients with assigned International Classification of Diseases (ICD) codes of AA and appendicitis-related symptoms between 2005 and 2017, 655 adults (2.3%) and 256 children (2.2%) had AA. For the LR model identifying AA diagnosis among adult ED patients, the c-statistic was 0.72 (95% CI: 0.69–0.75) for structured variables only, 0.72 (95% CI: 0.69–0.75) for unstructured variables only, and 0.78 (95% CI: 0.76–0.80) when including both structured and unstructured variables. For the LR model identifying AA diagnosis among pediatric ED patients, the c-statistic was 0.84 (95% CI: 0.79–0.89) for including structured variables only, 0.78 (95% CI: 0.72–0.84) for unstructured variables, and 0.87 (95% CI: 0.83–0.91) when including both structured and unstructured variables. The RF method showed similar c-statistic to the corresponding LR model. Conclusions We developed predictive models that can predict the AA diagnosis for adult and pediatric ED patients, and the predictive accuracy was improved with the inclusion of NLP elements and approaches.


2022 ◽  
Vol 22 (1) ◽  
Author(s):  
Mingyue Li ◽  
Ziyue Wang ◽  
Baisong Zhang ◽  
Tiantian Wei ◽  
Dan Hu ◽  
...  

Abstract Background A major challenge of prospective cohort studies is attrition in follow-up surveys. This study investigated attrition in a prospective cohort comprised of medical graduates in China. We described status of attrition, identified participants with higher possibility of attrition, and examined if attrition affect the estimation of the key outcome measures. Methods The cohort study recruited 3,620 new medical graduates from four medical universities in central and western China between 2015 and 2019. Online follow-up surveys were conducted on an annual basis. Follow-up status was defined as complete (meaning that the participant completed all the follow-up surveys) and incomplete, while incomplete follow-up was further divided into ‘always-out’, ‘rejoin’ and ‘other’. Multivariable logistic and linear regressions were used to examine factors predicting attrition and the influence on the outcome measures of career development. Results 2364 (65.3%) participants completed all follow-up surveys. For those with incomplete follow-up, 520 (14.4%) were ‘always-out’, 276 (7.6%) rejoined in the 2020 survey. Willingness to participate in residency training (OR=0.80, 95%CI[0.66 - 0.98]) and willingness to provide sensitive information in the baseline survey predicted a lower rate of attrition (providing scores for university entrance exam OR=0.82, 95%CI[0.69 - 0.97]]; providing contact information (OR=0.46, 95%CI[0.32 - 0.66]); providing household income (OR=0.60, 95%CI[0.43 - 0.84]). Participants with compulsory rural service (OR=1.52, 95%CI[1.05 - 2.19]) and those providing university entrance scores (OR=1.64, 95%CI[1.15-2.33)) were more likely to rejoin in the follow-up survey. These factors associated with follow-up status did not have significant impact on key outcome measures of career development. Conclusions Graduates who were unwilling to participate in residency training or not providing sensitive information should be targeted early in the cohort study to reduce attrition. More information about the study should be provided to those graduates early to facilitate their understanding of the meaning in participation. On the contrary, medical graduates with compulsory rural service and those who provided university entrance scores were more likely to rejoin in the cohort. The research team should invest more effort in contacting those graduates and returned them to the cohort.


2022 ◽  
Vol 22 (1) ◽  
Author(s):  
Rachel Visontay ◽  
Matthew Sunderland ◽  
Tim Slade ◽  
Jack Wilson ◽  
Louise Mewton

Abstract Background Research has long found ‘J-shaped’ relationships between alcohol consumption and certain health outcomes, indicating a protective effect of moderate consumption. However, methodological limitations in most studies hinder causal inference. This review aimed to identify all observational studies employing improved approaches to mitigate confounding in characterizing alcohol–long-term health relationships, and to qualitatively synthesize their findings. Methods Eligible studies met the above description, were longitudinal (with pre-defined exceptions), discretized alcohol consumption, and were conducted with human populations. MEDLINE, PsycINFO, Embase and SCOPUS were searched in May 2020, yielding 16 published manuscripts reporting on cancer, diabetes, dementia, mental health, cardiovascular health, mortality, HIV seroconversion, and musculoskeletal health. Risk of bias of cohort studies was evaluated using the Newcastle-Ottawa Scale, and a recently developed tool was used for Mendelian Randomization studies. Results A variety of functional forms were found, including reverse J/J-shaped relationships for prostate cancer and related mortality, dementia risk, mental health, and certain lipids. However, most outcomes were only evaluated by a single study, and few studies provided information on the role of alcohol consumption pattern. Conclusions More research employing enhanced causal inference methods is urgently required to accurately characterize alcohol–long-term health relationships. Those studies that have been conducted find a variety of linear and non-linear functional forms, with results tending to be discrepant even within specific health outcomes. Trial registration PROSPERO registration number CRD42020185861.


2022 ◽  
Vol 22 (1) ◽  
Author(s):  
Julia Ledien ◽  
Zulma M. Cucunubá ◽  
Gabriel Parra-Henao ◽  
Eliana Rodríguez-Monguí ◽  
Andrew P. Dobson ◽  
...  

AbstractAge-stratified serosurvey data are often used to understand spatiotemporal trends in disease incidence and exposure through estimating the Force-of-Infection (FoI). Typically, median or mean FoI estimates are used as the response variable in predictive models, often overlooking the uncertainty in estimated FoI values when fitting models and evaluating their predictive ability. To assess how this uncertainty impact predictions, we compared three approaches with three levels of uncertainty integration. We propose a performance indicator to assess how predictions reflect initial uncertainty.In Colombia, 76 serosurveys (1980–2014) conducted at municipality level provided age-stratified Chagas disease prevalence data. The yearly FoI was estimated at the serosurvey level using a time-varying catalytic model. Environmental, demographic and entomological predictors were used to fit and predict the FoI at municipality level from 1980 to 2010 across Colombia.A stratified bootstrap method was used to fit the models without temporal autocorrelation at the serosurvey level. The predictive ability of each model was evaluated to select the best-fit models within urban, rural and (Amerindian) indigenous settings. Model averaging, with the 10 best-fit models identified, was used to generate predictions.Our analysis shows a risk of overconfidence in model predictions when median estimates of FoI alone are used to fit and evaluate models, failing to account for uncertainty in FoI estimates. Our proposed methodology fully propagates uncertainty in the estimated FoI onto the generated predictions, providing realistic assessments of both central tendency and current uncertainty surrounding exposure to Chagas disease.


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