Healthcare system engagement and algorithm‐identified cancer incidence following initiation of a new medication

Purpose Implausibly high algorithm‐identified cancer incidence within a new user study after medication initiation may result from increased healthcare utilization (HU) around initiation (“catch‐up care”) that increases diagnostic opportunity. Understanding the relationships between HU prior to and around initiation and subsequent cancer rates and timing is important to avoiding protopathic bias. Methods We identified a cohort of 417 458 Medicare beneficiaries (2007–2014) aged ≥66 initiating an antihypertensive (AHT) after ≥180 days of non‐use. Initiators were stratified into groups of 0, 1, 2–3, and ≥4 outpatient visits (OV) 60–360 days before initiation. We calculated algorithm‐identified colorectal cancer (aiCRC) rates stratified by OVs and time since AHT initiation: (0–90, 91–180, 181–365, 366–730, and 731+ days). We summarized HU ‐360/+60 days around AHT initiation by aiCRC timing: (0–29, 30–89, 90–179, and ≥180 days). Results AiCRC incidence (311 per 100 000 overall) peaked in the first 0–90 days, was inversely associated with HU before initiation, and stabilized ≥180 days after AHT initiation. Catch‐up care was greatest among persons with aiCRCs identified