Study objective: The aim of this study was to compare 2 groups of patients with severe obstructive sleep apnea (OSA) who were taking medication for cardiovascular disease: those who were compliant with nasal continuous positive airway pressure (CPAP) treatment and those who refused treatment or were noncompliant with CPAP treament.
Methods: In a cohort of 2158 patients with severe OSA (apnea-hypopnea index >30) a 2-year prospective longitudinal assessment of adherence and persistence with 3 medication categories (antihypertensives, statins, and antiplatelets) was carried out using the administrative database of the National Health Service. Medication adherence was evaluated by calculating the medication possession ratio (%MPR = days supplylactual days to refill x 100) for each drug. Medication persistency was defined as the proportion of subjects having filled a prescription in the last 30 days of the 2-year period. CPAP use was assessed at every follow-up visit after the treatment was prescribed. Medication adherence was compared between patients who had adequate CPAP adherence (> 4 h/day) and those who declined CPAP therapy or had discontinued CPAP due to an average use of less than 4 hours per day.
Results: The average 2-year MPR for antihypertensives, statins, and antiplatelets was not different among patients who used CPAP (88%, 81%, 95%) or did not use CPAP (86%, 77%, 93%). Female sex and increased number of comorbidities were predictors of good medication adherence (MPR > 80%). The rates of persistence for the 3 studied medications after the 2-year observation period were not different between the 2 groups (patients with or without CPAP).
Conclusions: Medication adherence and persistence during a 2-year period for 3 well-known protective cardiovascular medications were not different in patients with severe OSA, whether or not they were treated with CPAP.