Background and Aims

Diabetes and hypertension are major risk factors for Cardiovascular Diseases (CVDs). Despite an increase in the availability of effective treatments, a majority of persons living with diabetes and hypertension do not have adequate blood pressure and glucose control. One of the major contributors is poor treatment adherence. This study aims to evaluate the impact treatment adherence has on patients with both diabetes and hypertension on CVD events and its clinical outcomes in Canada.

In this population-based retrospective cohort study, we identify 15,642 patients aged 18 years or older that were diagnosed with both diabetes and hypertension, and prescribed anti-diabetic and antihypertensive medications. Based on their estimated refill dates, these patients were first categorized as low- or high-drug adherence patients.

Because CVD events may include coronary heart disease, stroke, or heart failure and the causes of death are not available for our study population, CVD death is computed using the most recent systolic blood pressure distributions and the population attributable risks. Our primary outcome is the association between drug adherence and the risk of an acute severe CVD and mortality. Our secondary outcome is the association between drug adherence and intermediate clinical outcomes including: diastolic and systolic blood pressures, glycosylated hemoglobin, low-density lipoprotein cholesterol, and total cholesterol.

Summary of Findings

We aim to evaluate the association between polypharmacy adherence and their impact on cardiac outcomes and mortality, and intermediate clinical outcomes.

15,642 patients were identified with a diagnosis with diabetes and hypertension simultaneously, and those who were prescribed for any anti-diabetic and antihypertensive medications following their diagnosis. We estimated adherence as people had at least 7 scripts records in the four preceding quarters and one quarter after each quarter of interest. The cardiac events included coronary heart disease, stroke, and heart failure. As causes of death are not available, CVD death was computed using the most recent systolic blood pressure distributions and the population attributable risks. Intermediate clinical outcomes included diastolic and systolic blood pressures, glycated hemoglobin, low-density lipoprotein cholesterol, and total cholesterol.

The average adherence rate was 54.26%, 69.37%, 30.75%, and 52.83% for patients with anti-diabetic prescription, anti-hypertensive prescription, aspirin, and stain, separately. For solo medicine, the HR for CVD risk, CVD mortality, and all-cause mortality ranged 0.43-0.89, 0.20-0.61, and 0.21-0.63, separately, for those with treatment adherence≥80%. For multiple medicines, the HR for CVD risk, CVD mortality, and all-cause mortality ranged 0.56-0.82, 0.23-0.40, and 0.22-0.40, separately, for those with treatment adherence≥80%.

Progress

• Project completed

Research Team Members

Xiaolin Wei

Ross Upshur

Frank Sullivan

France Légaré

Sponsors and Funding Agencies

Diabetes Action Canada

Project Contact

Zhitong Zhang zhitong.zhang@utoronto.ca