(64) Hydrochlorothiazide and Non-Melanoma Skin Cancer in Residents of the Province of Ontario, Canada

Saturday, August 27, 2022

8:00 AM – 6:00 PM CEST

Location: Hall C

Publication Number: 738

Presenting Author(s)

Marina G. Birck
– Research Institute of the McGill University Health Centre, McGill University, Montreal, Quebec, Canada

Co-Author(s)

Cristiano S. Moura
– Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
Coraline Danieli, PhD
– Centre for Outcomes Research and Evaluation, The Research Institute of the McGill University Health Centre, Canada
Michal Abrahamowicz, PhD
– Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Canada
Louise Pilote, MD, MPH, PhD, FRCPC
– Centre for Outcomes Research and Evaluation, The Research Institute of the McGill University Health Centre, Canada
Sasha Bernatsky, MD, FRCPC, PhD
– Centre for Outcomes Research and Evaluation, The Research Institute of the McGill University Health Centre, QC, Canada

Background: Hydrochlorothiazide (HCTZ), a widely prescribed antihypertensive agent, has photosensitizing properties, and some concerns have been raised regarding skin cancer risk.

Objectives: To compare the risk of non-melanoma skin cancer (NMSC) between HCTZ versus angiotensin-converting enzyme inhibitor (ACEi) users.

Methods: We used data from the Ontario Health Study (OHS), an ongoing, prospective general population adult cohort. Since 2010, OHS has collected data on risk factors for several types of cancer and other chronic conditions, including smoking and skin/hair colour. For a subgroup of OHS participants, we obtained linked administrative data to ascertain longitudinal information on drug exposure and outcomes. We studied new-users of HCTZ or ACEi, who were free of NMSC at baseline, and had at least 12-months of enrollment in Ontario’s public drug insurance plan. Follow-up started at 12 months after the first prescription (lag time) and continued until NMSC, discontinuation/switching of initial treatment, death, or loss to follow-up. Multivariable Cox models were used to obtain adjusted hazard ratios (aHR) with 95% confidence intervals (95% CI). Models were adjusted for age, sex, smoking, hair colour, comorbidities, current and past use of immunosuppressant and other photosensitizing drugs, and family history of skin cancer.

Results: We studied 9,398 subjects, 42.9% female and most (56.5%) aged 65-74 years. Age distribution was similar between HCTZ and ACEI groups, with a trend for fewer females in the ACEI group (36% versus 54% in the HCTZ group). Other risk factors were evenly distributed among both groups. We identified 394 NMSC events during a median follow-up of 440 days (interquartile range, 131-1145). Incidence per 100 person-years was 2.05 (95% CI 1.74-2.43) for HCTZ and 2.30 (95% CI 2.03-2.60) for ACEI. Comparing HCTZ versus ACEI, the aHR was 1.04 (95% CI 0.82-1.32).

Conclusions: Adjusting for potential confounders and effect modifiers, we were unable to demonstrate a clear increase in NMSC in new-users of HCTZ versus ACEI. Potential limitations include a median follow-up time between 1-2 years. Future work will consist of additional studies in larger cohorts and an examination of sex and gender effects.