Self-reported adherence with medication and cardiovascular disease outcomes in the Second Australian National Blood Pressure Study (ANBP2)

Objective: To investigate whether responses to a previously validated four-item medication adherence questionnaire were associated with adverse cardiovascular events. Design: Survey conducted among a cohort of participants in the Second Australian National Blood Pressure Study. Setting: Australian general practice. Participants: 4039 older people with hypertension. Main outcome measures: All major cardiovascular events or death; first specific cardiovascular event. Results: Subjects who adhered to their medication regimen (compared with non-adherent subjects) were significantly less likely to experience a first cardiovascular event or a first non-fatal cardiovascular event (hazard ratio [HR] for both, 0.81; 95% CI, 0.67-0.98; P = 0.03); a fatal other cardiovascular event (HR, 0.68; 95% CI, 0.48-0.99; P = 0.04); or a first occurrence of heart failure (HR, 0.58; 95% CI, 0.37-0.90; P = 0.02). Those who answered yes to "Did you ever forget to take your medication?" were significantly more likely to experience a cardiovascular event or death (HR, 1.28; 95% CI, 1.04-1.57; P = 0.02); a first cardiovascular event or death (HR, 1.31; 95% CI, 1.07-1.60; P = 0.01); a first cardiovascular event (HR, 1.34; 95% CI, 1.09-1.65; P = 0.01); or a first non-fatal cardiovascular event (HR, 1.35; 95% CI, 1.09-1.66; P = 0.01). Those who answered yes to "Sometimes, if you felt worse when you took your medicine, did you stop taking it?" were significantly more likely to experience a first occurrence of heart failure (HR, 2.06; 95% CI, 1.16-3.64; P = 0.01). Conclusions: Subjects who adhered to their medication regimen were less likely to experience major cardiovascular events or death. The question relating to forgetting to take medication identified non-adherent subjects likely to experience a cardiovascular event or death. Clinicians could use this question to identify patients with hypertension who are likely to benefit from medication adherence strategies.