Ethnic Disparities in CPAP Adherence in New Zealand: Effects of Socioeconomic Status, Health Literacy and Self-Efficacy

STUDY OBJECTIVES: We aimed to investigate the influence of ethnicity on adherence with continuous positive airway pressure (CPAP) in a sample of New Zealand patients. DESIGN: Observational study over one month. SETTING: A university-based sleep laboratory. PATIENTS: 126 consecutively consenting CPAP-naïve patients (19.8% Māori, mean±SD apnea-hypopnea index 57.9 ± 38.9 events/h, CPAP 11.1 ± 3.1 cm H2O). INTERVENTIONS: Patients underwent a 4-week supervised home trial of CPAP following pressure titration. MEASUREMENTS AND RESULTS: Self-identified ethnicity (Māori/non-Māori), Epworth Sleepiness Scale, Self-Efficacy Measure for Sleep Apnea, Rapid Estimate of Adult Literacy in Medicine, New Zealand Deprivation Index (calculated from residential address), New Zealand Individual Deprivation Index (validated 8-item questionnaire), educational history, income, and employment assessed at baseline were compared to objective CPAP adherence after one month. Māori demonstrated significantly lower usage than non-Māori (median 5.11, interquartile range 2.24 h/night compared with median 5.71, interquartile range 2.61 h/night, P = 0.05). There were no significant relationships between adherence and subjective sleepiness, health literacy, or self-efficacy. In a multivariate logistic regression model incorporating 5 variables (ethnicity, eligibility for government-subsidized healthcare, individual deprivation scores, income, and education), non-completion of tertiary education, and high individual socioeconomic deprivation remained significant independent predictors of average CPAP adherence not reaching ≥ 4 h (odds ratio 0.25, 95% CI 0.08-0.83, P = 0.02; odds ratio 0.10, 95% CI 0.02-0.86, P = 0.04, respectively). The overall model explained approximately 23% of the variance in adherence. CONCLUSIONS: The disparity in CPAP adherence demonstrated between Māori and non-Māori can be explained in part by lower education levels and socioeconomic status.