Health belief model predicts adherence to CPAP before experience with CPAP

Adherence to Continuous Positive Airway Pressure (CPAP) therapy for Obstructive Sleep Apnoea (OSA) is often poor. Biomedical indices explain little of the variance in CPAP use. This study tested a Health Beliefs model of adherence to determine the contribution of psychological constructs as compared to biomedical indices in the prediction of CPAP adherence. 77 consecutive patients newly diagnosed with OSA and were naive to CPAP treatment (had never tried CPAP before) completed questionnaires at baseline (prior to CPAP treatment). Questionnaires assessed; outcome expectancy with treatment, self-efficacy, functional outcomes of sleepiness, and perceived risk of negative health outcomes. Physiological data from standard clinical diagnostic sleep study was obtained. CPAP adherence was assessed at 4 month follow-up. Health Beliefs Model constructs alone explained 21.8% of the variance in CPAP adherence (p<.01), whilst Health Beliefs Model constructs and biomedical indices together explained 31.8% of the variance in CPAP adherence (p=.01). The greatest proportion of CPAP adherence was explained by higher outcome expectancies with treatment, greater functional limitations as a result of sleepiness and lower risk perception. Results suggest that patients have developed beliefs and expectations about OSA and CPAP even before they have tried CPAP treatment. These beliefs and expectations predict patients’ adherence to effective therapy