OBJECTIVES: To analyze the impact of colorectal cancer (CRC) diagnosis on treatment adherence amongst patients with preexisting hypertension.

METHODS: This retrospective cohort utilized the SEER-Medicare linked database to identify patients who were enrolled in Medicare Part A, B, and D at the time of the index date from 2015 to 2019 and who were 65 years of age or older on the index date (defined as the date of colorectal cancer diagnosis), with pre-existing hypertension conditions, on anti-hypertensive medications (beta blockers, Angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs),calcium channel blockers and diuretics) at least 12 months before the index date, and a diagnosis of CRC at the index date. The change in adherence post CRC diagnosis based on study population were analyzed and the common drug classes on index date were determined.

RESULTS: Males (51.7%) and Whites (81.2%) accounted for the largest proportion of CRC patients with pre-existing hypertension among the total 6758 patients, whose mean age was 77.6 years. In comparison to post CRC diagnosis, 53.58% of participants had higher adherence, while 30.37% showed lower adherence. At index date, the most common drug class for hypertension was beta blockers (16.22%), followed by ACE (11.7%) and ARB (7.1%). Following a CRC diagnosis, 55.5% of individuals who had previously used one class of anti-hypertensive medication switched to a different class. The effect of change in treatment proportion was found to be higher in females (56%) and whites (81.2%).

CONCLUSIONS: Change in adherence in terms of population characteristics was explained by sex, and race. Future research needs to explore survival analysis and treatment discontinuation (time to event analysis).