Background: Cluster randomized control trials (cRCTs) are useful for asking about system-level interventions compared to other types of clinical research design, however they present unique challenges with conduct and delivery. Numerous cRCTs in hospitals have encountered challenges and time delays in enrolling hospitals and launching the trials which contributes to research waste. While each cRCT has unique barriers and enablers to their conduct, it is important to understand and explore these factors at the general level of the cRCT itself. Previous literature has documented factors associated with successful cRCTs, however, these studies focused primarily on the statistical aspect, while neglecting to evaluate the delivery of the trial. Objectives: The goal of this dissertation was to explore barriers and enablers to conducting cRCTs in hospitals, and to identify potential strategies that facilitate their delivery. This research was conducted to identify evidence and generate guidance for researchers aiming to conduct these trials. Specifically, the objectives were: 1) To explore the current knowledge and evidence surrounding the implementation of cRCTs in hospitals; 2) To explore from the perspective of the coordinating site, what influenced the delivery and hospital engagement of an ongoing cRCT, and what challenges were encountered; 3) To identify strategies to facilitate delivery of cRCTs in hospitals; 4) To systematically review reported recruitment strategies of healthcare facilities in cRCTs. Methods: The dissertation employed multiple research methods. To address the first objective, a scoping review was performed of current literature related to hospitals in cRCTs. The second objective was addressed with a qualitative case study. Semi-structured interviews were carried out with six key members of the team to understand their perceptions of the delivery of the trial. For the third objective, a tool matching two implementation concepts (the Consolidated Framework for Implementation Research (CFIR)- Expert Recommendations for Implementing Change (ERIC) matching tool) was used to identify strategies targeted to address barriers and enablers to cRCT conduct identified in the first two studies. Lastly, a systematic review was performed to address the fourth objective, to identify reported strategies used for hospital engagement in cRCTs. The thesis was guided and analyzed using an over-arching implementation framework, CFIR, and an implementation strategies list, the ERIC compilation. This was done to allow comparability and synthesis of results between methodologies from the dissertation, and between the results from the studies and previous literature. Results: Several key CFIR domains were identified in the literature in the scoping review that were determined to being influential for conducting the cRCTs in hospitals: the adaptability to tailor the trial to each site; the engagement of opinion leaders, champions and formally appointed implementation leaders in the cRCT process as facilitators to conducting the trial; the lack of a site perceiving a relative priority for the trial or tension for change for the clinical field presenting barriers to conducting the cRCT; and limited available resources can present barriers to conducting the cRCT. The qualitative case study identified similar CFIR domains and constructs as potentially influential for cRCT conduct, including the emphasis on adaptability of trial, the importance of tension for change in the sites for accepting inclusion in the trial, the availability of resources, and the engagement of leaders. The CFIR-ERIC matching study identified strategies that may be used to overcome barriers and target enablers for cRCT delivery from CFIR domains and constructs identified in the first two studies. A list of strategies was generated, ranked by the number of many determinants for which the strategy was listed as a Level 1 strategy, then by how many determinants for which the strategy was listed as a Level 2 strategy. The top ERIC strategies that were endorsed as a Level 1 strategy for any or multiple CFIR domains were: 1) Identify and prepare champions, 2) Conduct local needs assessment, 3) Conduct educational meetings, 4) Inform local opinion leaders, 5) Build a coalition, 6) Promote adaptability, 7) Develop a formal implementation blueprint, 8) Involve patients/consumers and family members, 9) Obtain and use patients/consumers and family feedback, 10) Develop educational materials, 11) Promote network weaving, 12) Distribute educational materials, 13) Access new funding, and 14) Develop academic partnerships. The systematic review identified literature reporting on the recruitment of healthcare facility sites into cRCTs. Numerous strategies for cRCT site recruitment were identified, and these were coded to the ERIC compilation. Strategies that were commonly cited were: involve executive boards, promote network weaving, conduct educational meetings, inform local opinion leaders, and centralize technical assistance. Conclusions: The results from the dissertation can contribute to the knowledge for facilitating cRCT delivery in hospitals while recognizing the critical limitations in the studies. Key concepts and strategies to facilitate the conduct and delivery of cRCTs in hospitals were identified. Future research should aim to empirically evaluate the identified strategies. Researchers should aim to address the reporting gap for cRCT delivery identified by this dissertation.

Participants in randomized control trials (RCTs) should be representative of those most likely to experience the disorder of focus, yet reviews of psychology research studies consistently find certain demographic groups are overrepresented at the price of others being unincluded. The present review aimed to characterize the demographic representation of US-based RCTs for gambling disorder and compare findings to the population of individuals most likely to experience the disorder. Thirteen US-based RCTs comprising a total of 2,343 participants were reviewed. We found that although gambling disorder is most prevalent among low SES racial minorities, RCTs are mostly conducted among populations who are white, employed, and have some level of college education. Demographic variables that are related to the likelihood of experiencing gambling disorder are not consistently reported, and there are many groups of individuals who experience gambling disorder that have been virtually left out of all treatment study samples to date. We conclude with recommendations for future gambling focused treatment studies, which are geared towards increasing the convergence between characteristics of participants in RCTs and those who experience gambling disorder in the United States.

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Vitamin D inadequacy is highly prevalent among pregnant women worldwide. Inadequacy or deficiency of vitamin D can lead to adverse outcomes during pregnancy such as pre-eclampsia, gestational diabetes, and caesarian section. A systematic review and meta-analysis were conducted to examine the effectiveness of vitamin D supplementation on serum vitamin D status during pregnancy in randomized controlled trials (RCTs). A search was conducted in PubMed, Scopus, ProQuest, EBSCO, Cochrane CENTRAL Database of Controlled Clinical Trials, PsycINFO, CINAHL, and Google Scholar, in addition to searching reference lists in published reviews. A comprehensive list of RCTs of vitamin D status and supplemental use in pregnancy was compiled. The random effects model was used to determine a summary effect size using pre/post means and standard deviations of serum vitamin D levels from intervention and control groups. Sixteen RCTs indicated a large effect size (d = .849, 95% CI .607 – 1.001, p < .001). Serum vitamin D concentration at delivery was higher with vitamin D supplementation, and thereby the metabolic outlook was favorable for the mother and newborn. Heterogeneity of the meta-analysis was significant (Q = 344.418, p < .001); the I-squared statistic showed moderate heterogeneity (61.89%), which warranted subgroup analysis to identify possible sources of variation among the studies. Moderators for subgroup analysis included vitamin D dosages, use of a placebo, use of multivitamins in addition to vitamin D, duration of interventions, age, low or adequate baseline vitamin D status, trimester when supplementation was started, country where the RCT was conducted (USA/UK/AUS versus other countries), and blinded versus non-blinded RCTs. Subgroup analysis only demonstrated a significant impact on heterogeneity from the trimester moderator (p < .001). Women who began vitamin D supplementation during the first trimester had a higher effect size and improved vitamin D status compared to those who began supplementation in the second or third trimester. Since pregnant women with vitamin D inadequacy or deficiency are more susceptible to complications, routine examination of vitamin D status should be conducted in pregnant women.

Parent-implemented interventions (PIIs) can be useful in promoting parents’ knowledge of autism spectrum disorder (ASD) and in transferring necessary skills to children with ASD. Individuals with ASD can directly and indirectly benefit from PIIs in terms of academics, ASD symptom severity, behavior improvement, cognition, communication, and social skills. Many studies have explored the efficacy of PIIs; however, they have tended to report mixed effects. Previous meta-analyses and systematic reviews have been characterized by limited search terms and literature search procedures, emphases on published manuscripts, dependency on parent reports, dated findings, and comparisons across of different types of control groups. This study attempts to improve on the methodology of prior meta-analyses and to update findings of the effectiveness of PIIs for children and youth with ASD. We located 1925 studies at initial manuscript search in 9 databases. After additional search from other sources, 43 studies met the inclusion criteria. Studies with same participants were merged that yield 40 records for final data coding. Eligible studies coded in Dyches et al.’s meta-analysis (2018) combined with current data resulted in 53 randomized controlled trials for data analysis. The random effects model meta-analysis found a moderate and statistically significant effect (g = 0.55, 95% CI 0.35 to 0.65, p < 0.00001) on overall weighted effect size across 53 studies included. PIIs can improve child outcomes in positive behavior/social skill (g = 0.603), maladaptive behavior (g = 0.519), adaptive behavior/life skills (g = 0.239), and language/communication (g = 0.545). These findings are inconclusive and should be interpreted with caution, especially adaptive behavior/life skill because only six studies reported outcomes on that variable. No moderating variables were identified in post hoc random effects weighted analyses. Implications for future research are discussed.

Cluster randomized controlled trials are increasingly used to assess the effectiveness of life-style interventions in improvement of health services or prevention of disease. However, statistical methods in the analysis of cluster randomized controlled trials are not well established especially for analyzing binary outcomes. This project is motivated by the Community Hypertension Assessment Trial (CHAT) to assess the effectiveness of a 12-month community-based blood pressure management program in improving the management and monitoring of high blood pressure (BP) among older people. The study is a paired cluster randomized controlled trial, where the family physicians' practices are the clusters randomly allocated to CHAT intervention or usual practice, and a random sample of 55 patients 65 years and older were selected from the 14 practices in each study arm for health record review. The primary outcome was controlled BP over 12 months defined as systolic BP c:; 140 and diastolic BP c:; 90 for patients without diabetes or target organ damage or systolic BP c:; 130 and diastolic BP c:; 80 for patients with diabetes or target organ damage. Secondary outcomes include frequency of BP monitoring and average BP over a 12 month period. The clinical objective of this project is to evaluate the effectiveness of the CHAT intervention. The statistical objective is to compare Bayesian and classical methods of analyzing cluster-randomized trials using CHAT study as an example. We compared the results of different cluster-level analysis methods: i) un-weighted regression, ii) weighted regression, iii) random-effects meta-analytic approach, and different individual-level analyses: i) standard logistic regression, ii) robust standard errors approach, iii) generalized estimating equations, iv) random-effect logistic regression, v) Bayesian random-effect regression. We find that there is no sufficient evidence in support of the effectiveness of the CHAT intervention on all outcomes. For BP control, odds ratio (95% confidence interval) is 1.14 (0.72, 1.80) from generalized estimating equations. This result remains robust under different methods. We also find that the results from different statistical methods are different. The results from cluster-level analysis methods are quite different, while the results from the individual-level analysis methods are similar. We conclude that using various methods to analyze the trial provide good sensitivity analyses to help in interpreting the results of cluster randomized trials. Extensive simulation studies comparing the statistical powers of the different methods in different situations are required. / Thesis / Master of Science (MS)

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