Browsing by Subject "meta-analysis"
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Item A bias correction method in meta-analysis of randomized clinical trials with no adjustments for zero-inflated outcomes(John Wiley & Sons, Inc., 2021-09-03) Zhou, Zhengyang; Xie, Minge; Huh, David; Mun, Eun-YoungMany clinical endpoint measures, such as the number of standard drinks consumed per week or the number of days that patients stayed in the hospital, are count data with excessive zeros. However, the zero-inflated nature of such outcomes is sometimes ignored in analyses of clinical trials. This leads to biased estimates of study-level intervention effect and, consequently, a biased estimate of the overall intervention effect in a meta-analysis. The current study proposes a novel statistical approach, the Zero-inflation Bias Correction (ZIBC) method, that can account for the bias introduced when using the Poisson regression model, despite a high rate of inflated zeros in the outcome distribution of a randomized clinical trial. This correction method only requires summary information from individual studies to correct intervention effect estimates as if they were appropriately estimated using the zero-inflated Poisson regression model, thus it is attractive for meta-analysis when individual participant-level data are not available in some studies. Simulation studies and real data analyses showed that the ZIBC method performed well in correcting zero-inflation bias in most situations.Item Do brief motivational interventions increase motivation for change in drinking among college students? A meta-analysis of individual participant data(2022-08) Tan, Zhengqi; Mun, Eun-Young; Walters, Scott T.; Zhou, Zhengyang; Huh, David; Nandy, Rajesh R.Brief Motivational Interventions (BMIs) have been identified as one of the most effective individually focused alcohol intervention strategies for college students in the United States. Despite the central role of motivation for change in BMIs, whether BMIs increase motivation for change has rarely been investigated. The current study conducted a meta-analysis of individual participant data (IPD; 15 studies, N = 5,903) from Project INTEGRATE (Mun et al., 2015) to examine whether BMIs increase motivation for change in drinking. Different measures and responses used in the original trials were harmonized across studies, and effect size estimates were derived from a model that adjusted for baseline motivation and demographic variables for each study (step 1) and subsequently combined in a random-effects meta-analysis model (step 2). After adjustment for baseline levels of motivation level and demographic variables, the intervention effects of BMIs on motivation for change was not statistically significant (standard mean difference [SMD]: 0.026, 95% CI: [-0.001, 0.053], p = .06, k = 19). Subsequent metaregression analyses among BMI subtypes indicated that the intervention effect did not differ between individually delivered motivational interviewing with personalized feedback (MI+PF), stand-alone personalized feedback (PF), and group-based motivational interviewing (GMI). Among all BMI subtypes, only GMI had a statistically significant intervention effect on motivation compared to controls (SMD: 0.055, 95% CI: [0.007, 0.103], p = .025, k = 5). Within the first three months post-intervention, there was a decrease in SMD of 0.05 (95% CI: [0.01, 0.08]) in motivation per month. However, no statistically significant difference in the intervention effects was found between studies with short-term vs. long-term follow-up. Although the results from the current study do not support the hypothesis that BMIs improve motivation for change, the evidence as a whole suggests ways in which motivation may be improved following intervention and can be tested in future studies.Item Public Opinion of the Uninsured: Who Are They? Can They Get Care? Should Insurance be Publically Provided(2001-07-01) Miller, Rachel; Kristine Lykens; Doug A. Mains; Karan SinghThe United States is at the pinnacle of medical expertise and exploration. Many people from around the world come here to receive that outstanding care. Unfortunately, many of our own citizens are unable to enjoy that same privilege. With mounting technological and research costs, Health Maintenance Organizations, State-funded health insurance, and federally funded programs, such as Medicaid, are struggling to meet the expanding numbers of uninsured. The public is the driving force behind the policy debate in this country, and the debate over the uninsured may be lacking some very important information. It was the aim of this study to evaluate the public’s view of the uninsured. Meta-analysis was used to evaluate three questions regarding the public’s opinions of the status of the uninsured in the country to better understand the true perception held.Item Variation in the Branching Pattern of the Internal Iliac Artery(2016-05-01) Chase, Jeff; Claire A. Kirchhoff; Patricia A. Gwirtz; Rustin E. ReevesThe purpose of this project is to report, analyze and interpret the anatomical variability of the branches of the internal iliac artery, while exploring clinical correlations and forming solutions to alleviate potential student confusion. Branching patterns were observed and recorded by medical students using anatomical variation data sheets (n=111). A meta-analysis of anatomy textbooks and atlases (n=20) was conducted to find out how often the variability of the internal iliac artery is mentioned or depicted. This provided proxy data on whether or not students might have had knowledge of possible variation, and if so what kind of information was given. Internal pudendal artery, inferior gluteal artery and middle rectal artery all variably share trunks with one or more of the other arteries. This variability was commonly found in research publications but was inconsistently explained or depicted in textbooks and atlases. When it was mentioned or shown, statistical evidence of frequencies was not used adequately. Providing students, clinicians and researchers with an accurate representation of the branching pattern will enable better understanding, improving educational and clinical outcomes.