Adherence to antihypertensive medications among family practice patients with diabetes mellitus and hypertension

Objective To measure adherence and to identify factors associated with adherence to antihypertensive medications in family practice patients with diabetes mellitus (DM) and hypertension. Design A cross-sectional study using a mailed patient self-report survey and clinical data. Setting Twenty-seven family physician and nurse practitioner clinics from Nova Scotia, New Brunswick, and Prince Edward Island (the Maritime Family Practice Research Network). Participants A total of 527 patients with type 2 DM and hypertension who had had their blood pressure measured with the BpTRU (an automated oscillometric instrument) at family practice clinic visits within the previous 6 months. Main outcome measures Level of adherence to antihypertension medications as measured by patients' self-report on the Morisky scale; association between high adherence on the Morisky scale and 22 patient factors related to demographic characteristics, clinical variables, knowledge, beliefs, behaviour, health care provider relationships, and health system influences. Results The survey response rate was 89.6%. The average age of patients was 66 years, and 51.6% of participants were men. Forty-three percent of patients had had a diagnosis of DM for more than 10 years, and 49.7% had had a diagnosis of hypertension for more than 10 years. Eighty-nine percent of patients had some form of medical insurance. All patients had seen their family physician providers at least once within the past year. Seventy-seven percent of patients reported high adherence as measured by the Morisky scale. On multiple logistic regression, being older than 55, taking more than 7 prescribed medications, and having a lifestyle that included regular exercise or a healthy diet with low salt intake or both were significant independent predictors of high adherence scores on the Morisky scale (P > .05). Conclusion More than three-quarters of patients with type 2 DM and hypertension from community family practice clinics in Maritime Canada reported high adherence to their antihypertensive medications. Family physicians and nurse practitioners can apply strategies to improve antihypertensive medication adherence among type 2 DM patients who are younger, taking fewer medications, or not maintaining a lifestyle that includes regular exercise or a healthy diet or both. Future studies will need to determine whether focusing adherence strategies on these patients will improve their cardiovascular outcomes.