Statistical Analysis Plan
Numerical summaries for continuous demographic variables were reported with medians and IQR (interquartile range, 75% th - 25% th) and frequencies and percentages for categorical variables. Demographic, baseline disease, disease complication, and treatment variables between SCD genotype groups and weight status groups were compared using Chi-square tests or Fisher’s exact test with Monte Carlo estimates for categorical variables and Kruskal–Wallis tests for continuous variables. The weight status of patients with SCD at UMMC, who were 10-17 years, was compared to state and national proportions of 10-17 year olds from the 2016-2017 National Survey of Children’s Health using two-sample tests of proportion. Variables that were found to be related to weight status (p < 0.10) were identified as potential risk factors. To examine how these potential risk factors may affect the relationship between SCD genotype and weight status, multiple logistic regressions models were conducted with risk factor groups accounted for sequentially. The odds ratio (OR) and 95% confidence intervals for genotype [HbSS/HbSβ° (ref) vs HbSC/ HbSβ+] were reported for each model. All statistical analyses were performed using Stata 16.0.