Antihypertensive Medication Adherence and Cardiovascular Outcomes in Patients With Cancer: A Nationwide Population‐Based Cohort Study

BACKGROUND: Hypertension is an important cause of morbidity, which predisposes patients to major cardiovascular events and mortality. The aim of this study was to explore the association between adherence to antihypertensive medication and clinical outcomes in adult patients with cancer. METHODS AND RESULTS: Using the 2002 to 2013 Korean National Health Insurance Service–National Sample Cohort, we extracted adult patients with cancer treated with antihypertensive medications. Based on the medication possession ratio value, participants were divided into 3 groups: good (medication possession ratio ≥0.8), moderate (0.5≤ medication possession ratio <0.8), and poor (medication possession ratio <0.5) adherence groups. The primary outcomes were overall and cardiovascular mortality. The secondary outcome was cardiovascular events requiring hospitalization due to major cardiovascular diseases. Among 19 246 patients with cancer with concomitant hypertension, 66.4% were in the nonadherence group (26.3% were moderate and 40.0% were poor adherence group). Over a median of 8.4 years of follow‐up, 2752 deaths and 6057 cardiovascular events occurred. Compared with the good adherence group, the moderate and poor adherence groups had a 1.85‐fold and 2.19‐fold increased risk for overall mortality, and 1.72‐fold and 1.71‐fold elevated risk for cardiovascular mortality, respectively, after adjustment for possible confounders. Furthermore, the moderate and poor adherence groups had a 1.33‐fold and 1.34‐fold elevated risk of new‐onset cardiovascular events, respectively. These trends were consistent across cardiovascular event subtypes. CONCLUSIONS: Nonadherence to antihypertensive medication was common in patients with cancer and was associated with worse clinical outcomes in adult patients with cancer with hypertension. More attention should be paid to improving adherence to antihypertensive medication among patients with cancer.