To adhere or not to adhere--patients selectively decide

Predictors of continuous positive airway pressure adherence

Continuous positive airway pressure (CPAP) is the leading treatment for obstructive sleep apnoea (OSA), a prevalent disorder of breathing in sleep strongly associated with obesity. OSA has serious adverse health, social and community effects arising from disturbed breathing, loud snoring, poor quality sleep and cardiovascular sequelae. When used appropriately, CPAP treatment is highly effective in normalising breathing and sleep, improving symptoms and lowering adverse event risk. However, patients do not necessarily accept, tolerate or comply with treatment, with many factors influencing CPAP uptake and longer term use. Although knowledge to address challenges affecting CPAP adherence and CPAP mask and machine technologies continue to improve incrementally, optimising CPAP treatment adherence is an ongoing challenge in sleep medicine.

Adherence to sleep apnea therapy and use of lipid-lowering drugs: a study of the healthy-user effect

BACKGROUND

Evidence that continuous positive airway pressure (CPAP) reduces cardiovascular morbidity comes largely from observational studies. This association may be confounded if CPAP adherents are healthier in ways not measured by investigators. We assessed whether patients adhering to lipid-lowering medications were more adherent to CPAP.

METHODS

This was a retrospective cohort study undertaken at the Philadelphia Veterans Affairs (VA) Medical Center (2005-2006) of consecutive patients on lipid-lowering therapy newly initiating CPAP for obstructive sleep apnea. Adherence to medications dispensed via the VA closed-pharmacy system was measured as the proportion of days covered (>/=80% vs < 80%) in the year prior to CPAP initiation. CPAP adherence was defined as >/= 4 h/d of "mask-on" time, measured electronically daily during the first week of CPAP. We examined the association between medication adherence and CPAP adherence using multivariable logistic regression.

RESULTS

Complete data were available for 117 of 142 (81.5%) subjects. After adjustment for age, race, medical comorbidity, and sleep apnea-related clinical factors, subjects with low medication adherence demonstrated a 40.1% (95% CI, 30.0-51.0) probability of using CPAP >/= 4 h/d compared with 55.2% (95% CI, 46.9-63.1) for subjects with adequate (>/=80%) medication adherence (adjusted for comparison, odds ratio (OR) = 1.8 [95% CI, 1.0-3.3], P = .04). Married patients were more adherent to medications and CPAP; inclusion of this factor reduced to nonsignificance the association of medication and CPAP adherence (OR = 1.6 [95% CI, 0.9-2.8], P = .12).

CONCLUSION

Patients consistently refilling lipid-lowering medications were more adherent to CPAP, suggesting that differences in medication adherence or other health-promoting behaviors should be investigated in future nonrandomized, observational studies linking CPAP adherence and cardiovascular outcomes.