Use of hydrochlorothiazide in Denmark following publication of skin cancer risk findings

Purpose The antihypertensive agent hydrochlorothiazide has recently been linked to increased risk of skin cancer. We sought to describe the impact of the dissemination of these findings on the use of hydrochlorothiazide and health care utilization among antihypertensive users in Denmark. Methods In this nationwide observational study, we performed descriptive analyses of a cohort comprising all Danish antihypertensive treatment users January 2016 through September 2020 (n = 1 316 476) with special focus on hydrochlorothiazide users (n = 309 743). Data were retrieved from the Danish nationwide health registries, including the Danish National Prescription Registry. Results The use of hydrochlorothiazide dropped by 44% from January 2016 to September 2020, with the proportion of all antihypertensive fills constituted by hydrochlorothiazide dropping from 12.7% to 7.2%. This decline was more pronounced among younger patients and patients with a history of skin cancer. Simultaneously, the monthly rate of new hydrochlorothiazide users in Denmark dropped from approximate to 2350 throughout 2017 to 652 during 2020. The publication of an increased risk of nonmelanoma skin cancer led to an estimated excess of up to 11 510 physical and 22 870 e-mail/phone consultations to general practitioners. No evidence for increased risk of adverse outcomes was found. Conclusions The publication of increased risk of skin cancer with hydrochlorothiazide use has led to a marked decline in the use of hydrochlorothiazide in Denmark. A temporary increase in rate of GP contacts was also observed. This highlights the potential impact from disseminating research findings to patients and clinicians.