Use of Hydrochlorothiazide in the United States Following Label Update About Skin Cancer Risk

Background: On August 20, 2020, the United States (US) Food and Drug Administration (FDA) issued a Drug Safety Communication (DSC) along with a label update to inform the public about a small increased risk of non-melanoma skin cancer associated with hydrochlorothiazide (HCTZ) use. The DSC advised that patients continue HCTZ use and take protective measures for skin cancer, unless otherwise instructed by healthcare providers.

Objectives: To evaluate the impact of this DSC and label update on HCTZ use.

Methods: We conducted trend analyses using claims data in the Sentinel Distributed Database and MerativeTM MarketScan® Research Databases from January 2017 to November 2022. We identified two cohorts each month: an overall cohort with all eligible members, and a skin cancer cohort consisting of individuals with a preexisting skin cancer diagnosis. The exposure of interest was the use of HCTZ-containing products during each month. For each cohort, we examined two outcomes of interest: 1) the monthly proportion of patients with HCTZ among those with any thiazide diuretics; and 2) the monthly proportion of patients with HCTZ among those with any antihypertensives (in MerativeTM MarketScan® only). To quantify the impact of the DSC on HCTZ use, we conducted interrupted time series analyses separately for each outcome, which examined 1) level change (change in the monthly proportion of HCTZ use immediately after the DSC) and 2) trend change (difference in the slopes of monthly proportion of HCTZ use after versus before the DSC).

Results: In the overall cohort, the monthly proportion of HCTZ use among thiazide users dropped slightly from 94.1% in January 2017 to 91.8% in November 2022. The DSC was not associated with level change (0.031%, 95% confidence interval [CI]: -0.020% to 0.082%) and was associated with a statistically significant yet clinically negligible trend change (0.018%, 95% CI: 0.012% to 0.025%) for this outcome. The monthly proportion of HCTZ use among antihypertensive users also declined from 33.0% in January 2017 to 27.3% in November 2022. The DSC was not associated with level (-0.045%, 95% CI: -0.316% to 0.227%) or trend change (-0.003%, 95% CI: -0.027% to 0.022%) for this outcome. In the skin cancer cohort, both monthly proportions of HCTZ use measures had only a statistically significant but clinically negligible trend change (0.022%, 95% CI: 0.014% to 0.030% among thiazide users; 0.031%, 95% CI: 0.006% to 0.057% among all antihypertensive users) after the DSC.

Conclusions: In the US, we did not observe clinically meaningful changes in HCTZ use following the DSC and label update regarding skin cancer risk, among the overall population and those with a history of skin cancer. Our findings are in accordance with the DSC advice.