Purpose: We sought to: (1) determine the odds of colorectal cancer (CRC) survivors being diagnosed with hypertension 2 years post-CRC diagnosis; (2) assess differences in blood pressure (BP) control one year post-CRC diagnosis; and (3) assess differences in antihypertensive medication adherence one year post-CRC diagnosis, all relative to matched non-cancer controls.
Background: CRC and hypertension share common risk factors. Because CRC survivors often transition from oncology-led care to primary care, it is important to know whether they have differential prevalence of hypertension for chronic disease management.
Methods: We used the national VA Central Cancer Registry to identify patients diagnosed with non-metastatic CRC from 10/1/2008 to 12/31/2012 who had ≥ 1 primary care or oncology visit in the previous year. Up to 3 non-cancer controls were identified for each CRC survivor through electronic health records matched on age, race, sex, copayment status, geographic region, distance to VA healthcare, body mass index, number of outpatient visits (≥ 3 vs. fewer), and pre-existing hypertension, hyperlipidemia, and diabetes. We used logistic regression to calculate odds ratios (OR) and confidence intervals (CI) for being diagnosed with, and control of, hypertension between CRC survivors and controls. We calculated Medication Possession Ratio (MPR), a pharmacy refill-based adherence measure, for patients prescribed metoprolol tartrate.
Results: 9,758 patients with CRC were matched to 29,066 controls. The cohort was predominantly white (79.5%) men (97.8%), mean age of 66.8 years. Compared to matched controls, CRC survivors had 60% higher odds of being diagnosed with hypertension (OR = 1.59, 95% CI, = 1.51-1.67) one year post-diagnosis (69.4% CRC survivors have hypertension). CRC survivors experienced lower odds of BP control (OR = 0.89, 95% CI, 0.85-0.94); antihypertensive medication adherence was lower (relative MPR difference 7%) compared with matched non-cancer controls.
Implications: Compared to patients without a history of cancer, CRC survivors have higher odds of being diagnosed with hypertension, worse BP control, and worse antihypertension medication adherence. A critical component of survivorship care for CRC patients is management of hypertension to reduce CVD risk.