0552 Predictive Characteristics of Run-In Period Adherence in a Randomized Controlled Trial

Abstract Introduction The run-in period has been used in randomized controlled trials in obstructive sleep apnea (OSA) to assess continuous positive airway pressure (CPAP) adherence. We hypothesize that there are differences in participant characteristics and PAP adherence between those excluded after the run-in period and those included in the final analytic sample of the Sleep Apnea Stress Study (SASS, NCT00607893), a trial designed to examine effect of PAP treatment on intermediate cardiovascular outcomes. Methods The SASS trial was designed to include a 2-week run-in period with a 1-month wash-out period. Patients with CPAP adherence >4 hours of CPAP use for 70% of run-in period nights were randomized. Demographic factors were compared among groups using analysis of variance (ANOVA) or Kruskal-Wallis test in continuous variables, Pearson’s chi-square test or Fisher’s exact test was used for categorical variables. Bonferroni correction was applied for pairwise comparisons. SAS version 9.4 (The SAS Institute Cary, NC) was used to perform all analyses. Results Fifty-nine participants(30.8%) who did not meet PAP adherence threshold were excluded after run-in period and compared to Sham and CPAP treatment group(n=74 in each group). Results are presented as excluded vs sham treatment vs CPAP treatment. Participants excluded after the run-in period were more likely to be female than those who proceeded to randomization: 66% vs. 47% vs. 45%,p=0.031 and of Black race:73% vs. 42% vs. 47%, p=0.002. Participants excluded after the run-in period and those non-adherent to treatment in sham and CPAP were younger than adherent participants: excluded: 48.9±12.0, sham non-adherent 49.7±12.3, CPAP non-adherent 47.7 ± 13.2, sham adherent 58.3±9.3, CPAP non-adherent 54.3 ± 9.4, p=0.014. In the run-in period, participants who were excluded had the median of number of days using the device 12 (IQR 7-15), mean of average daily use 2.8±2.1 hours and median percent of days with 4+ hours use 18.2% (IQR 0-57.1%). Conclusion We identify that age and race are predictors of run-in period non-adherence to PAP therapy underscoring the need to develop pre-randomization PAP adherence optimization strategies specific to these subgroups to ensure representation in the trial. Support (if any) This work was supported by NIH HL079114-02.