Statistical Analysis
SECONDARY
The effective SDs for the change in physical health and psychological QOL scores from preliminary data (baseline to after treatment, 14.7 and 10.4 units, respectivelyWe used SAS, version 9.4 (SAS Institute Inc), for analyses. We used intention-to-treat principles. We applied a shared-baseline, linear mixed model with completely unstructured covariance (selected through examination of model fit indices) among up to 4 repeated measurements (baseline, after treatment, and 6- and 12-month follow-up) and unstructured random visit-specific effects by session cohort to examine treatment effects on the primary and secondary outcomes. We ran a series of contrasts to assess the specific hypotheses about the within-group and between-group differences in the outcome variables at different time points. The model included all available data, including data from participants with incomplete evaluations and those lost to follow-up. The estimated covariance among repeated measurements implicitly imputes missing data and yields unbiased estimates under a missing-at-random assumption. The shared-baseline assumption represents the actual state of the population before randomization. It has the advantage of adjusting for chance differences at baseline in the same way as analysis of covariance.Treatment-dependent differences on changes from baseline to after treatment and to 6- and 12-month follow-up, and persistence of a benefit after treatment to the 6- and 12-month follow-up for each outcome were estimated from linear contrasts of least-square means and reported as point estimates and their unadjusted 95% CIs. Superiority of 3RP-NF at baseline to after treatment was based on a 2-tailed We performed sensitivity analyses. We tested treatment-dependent differences in the change of score from baseline to after treatment and at 6- and 12-month follow-up using the Wilcoxon rank-sum test to relax the parametric assumptions of the mixed model. We investigated more parsimonious covariance structures using random participant-specific intercepts, slopes, and quadratic terms (ie, growth curve analysis).Primary inference of efficacy was based on the estimated mean difference between 3RP-NF and HEP-NF in change from baseline to after treatment for primary outcomes of physical health and psychological QOL scores, testing each at a 2-tailed 