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Many statistical models have been proposed in the literature for the analysis of longitudinal data. One may propose to model two or more correlated longitudinal processes simultaneously, with a goal of understanding their association over time. Joint modeling is then required to carefully study the association structure among the outcomes as well as drawing joint inferences about the different outcomes. In this study, we sought to model the associations among six nutrition outcomes while circumventing the computational challenge posed by their clustered and high‐dimensional nature. We analyzed data from a 2 ×$\times$ 2 randomized crossover trial conducted in Kenya, to compare the effect of high‐dose and low‐dose iodine in household salt on systolic blood pressure (SBP) and diastolic blood pressure (DBP) in women of reproductive age and their household matching pair of school‐aged children. Two additional outcomes, namely, urinary iodine concentration (UIC) in women and children were measured repeatedly to monitor the amount of iodine excreted through urine. We extended the model proposed by Mwangi et al. (2021, Communications in Statistics: Case Studies, Data Analysis and Applications, 7(3), 413–431) allowing flexible piecewise joint models for six outcomes to depend on separate random effects, which are themselves correlated. This entailed fitting 15 bivariate general linear mixed models and deriving inference for the joint model using pseudo‐likelihood theory. We analyzed the outcomes separately and jointly using piecewise linear mixed‐effects (PLME) model and further validated the results using current state‐of‐the‐art Jones and Kenward methodology (JKME model) used for analyzing randomized crossover trials. The results indicate that high‐dose iodine in salt significantly reduced blood pressure (BP) compared to low‐dose iodine in salt. Estimates for the random effects and residual error components showed that SBP and DBP had strong positive correlation, with effect of the random slope indicating that significantly related outcomes are strongly associated in their evolution. There was a moderately strong inverse relationship between evolutions of UIC and BP both in women and children. These findings confirmed the original hypothesis that high‐dose iodine salt has significant lowering effect on BP. We further sought to evaluate the performance of our proposed PLME model against the widely used JKME model, within the multivariate joint modeling framework through a simulation study mimicking a 2×2$2\times 2$ crossover design. From our findings, the multivariate joint PLME model performed exceptionally well both in estimation of random‐effects matrix (G) and Hessian matrix (H), allowing satisfactory model convergence during estimation. It allowed a more complex fit to the data with both random intercepts and slopes effects compared to the multivariate joint JKME model that allowed for random intercepts only. When a hierarchical viewpoint is adopted, in the sense that outcomes are specified conditionally upon random effects, the variance–covariance matrix of the random effects must be positive definite. In some cases, additional random effects could explain much variability in the data, thus improving precision in estimation of the estimands (effect size) parameters. The key highlight in this evaluation shows that multivariate joint JKME model is a powerful tool especially while fitting mixed models with random intercepts only, in crossover design settings. Addition of random slopes may lead to model complexities in most cases, resulting in unsatisfactory model convergence during estimation. To circumvent convergence pitfalls, extention of JKME model to PLME model allows a more flexible fit to the data (generated from crossover design settings), especially in the multivariate joint modeling framework. [ABSTRACT FROM AUTHOR]

Composite scores are useful in providing insights and trends about complex and multidimensional quality of care processes. However, missing data in subcomponents may hinder the overall reliability of a composite measure. In this study, strategies for handling missing data in Paediatric Admission Quality of Care (PAQC) score, an ordinal composite outcome, were explored through a simulation study. Specifically, the implications of the conventional method employed in addressing missing PAQC score subcomponents, consisting of scoring missing PAQC score components with a zero, and a multiple imputation (MI)-based strategy, were assessed. The latent normal joint modelling MI approach was used for the latter. Across simulation scenarios, MI of missing PAQC score elements at item level produced minimally biased estimates compared to the conventional method. Moreover, regression coefficients were more prone to bias compared to standards errors. Magnitude of bias was dependent on the proportion of missingness and the missing data generating mechanism. Therefore, incomplete composite outcome subcomponents should be handled carefully to alleviate potential for biased estimates and misleading inferences. Further research on other strategies of imputing at the component and composite outcome level and imputing compatibly with the substantive model in this setting, is needed. [ABSTRACT FROM AUTHOR]

Background: Severe acute malnutrition (SAM) remains a major cause of admission and inpatient mortality worldwide in children aged less than 5 years. In this study, we explored SAM prevalence and outcomes in children admitted in 13 Kenyan hospitals participating in a Clinical Information Network (CIN). We also describe their immediate in-patient management. Methods: We analyzed data for children aged 1–59 months collected retrospectively from medical records after discharge. Mean, median and ranges were used to summarize pooled and age-specific prevalence and mortality associated with SAM. Documentation of key signs and symptoms (S/S) and performance of indicators of quality of care for selected aspects of the WHO management steps were assessed. Logistic regression models were used to evaluate associations between documented S/S and mortality among SAM patients aged 6–59 months. Loess curves were used to explore performance change over time for indicators of selected SAM management steps. Results: 5306/54140 (9.8%) children aged 1–59 months admitted with medical conditions in CIN hospitals between December 2013 and November 2016 had SAM. SAM prevalence identified by clinicians and case fatality varied widely across hospitals with median proportion (range) of 10.1% (4.6–18.2%) and 14.8% (6.0–28.6%) respectively. Seventeen variables were associated with increased mortality. Performance change over time of management steps varied across hospitals and across selected indicators but suggests some effect of regular audit and feedback. Conclusion: Identification of SAM patients, their mortality and adherence to in-patient management recommendations varied across hospitals. An important group of SAM patients are aged less than 6 months. Continued efforts are required to improve management of SAM in routine settings as part of efforts to reduce inpatient mortality. [ABSTRACT FROM AUTHOR]

Voluntary medical male circumcision (VMMC) reduces men's risk of acquiring Human immunodeficiency virus (HIV) through vaginal sex. However, VMMC uptake remains lowest among Kenyan men ages 25-39 years among whom the impact on reducing population-level HIV incidence was estimated to be greatest at the start of the study in 2014. We conducted a pre- and post-intervention survey as part of a cluster randomized controlled trial to determine the effect of two interventions (interpersonal communication (IPC) and dedicated service outlets (DSO), delivered individually or together) on improving VMMC uptake among men ages 25-39 years in western Kenya between 2014 and 2016. The study had three intervention arms and a control arm. In arm one, an IPC toolkit was used to address barriers to VMMC. In arm two, men were referred to DSO that were modified to address their preferences. Arm three combined the IPC and DSO. The control arm had standard of care. At baseline, uncircumcised men ranked the top three reasons for remaining uncircumcised. An IPC demand creation toolkit was used to address the identified barriers and men were referred for VMMC at study-designated facilities. At follow-up, those who remained uncircumcised were again asked to rank the top three reasons for not getting circumcised. There was inconsistency in ranking of reported barriers at pre- and post- intervention: 'time/venue not convenient' was ranked third at baseline and seventh at follow-up; 'too busy to go for circumcision' was tenth at baseline but second at follow-up, and concern about 'what I/family will eat' was ranked first at both baseline and follow-up, but the proportion reduced from 62% to 28%. Men ages 25-39 years cited a variety of logistical and psychosocial barriers to receiving VMMC. After exposure to IPC, most of these barriers shifted while some remained the same. Additional innovative interventions to address on-going and shifting barriers may help improve VMMC uptake among older men., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Agot et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)