Use of hydrochlorothiazide and risk of nonmelanoma skin cancer in Koreans: a retrospective cohort study using administrative healthcare data

Background The incidence of skin cancer is increasing because of the ageing population and ultraviolet exposure, and previous studies have revealed that long-term use of hydrochlorothiazide (HCTZ), an antihypertensive agent, has been associated with an increased risk of nonmelanoma skin cancer (NMSC). However, the association of NMSC and HCTZ within East Asian populations is unclear. Aim To investigate the risk of NMSC in Korean subjects using HCTZ. Methods A retrospective cohort study was conducted using the administrative healthcare data. The study enrolled 62 243 patients exposed to HCTZ with a cumulative dose of >= 2500 mg and 62 243 unexposed subjects matched 1 : 1 with the patients for age, sex and income level. Results There was a significant difference in the cumulative incidence of NMSC between the two groups (log-rank P < 0.01). Cox regression analysis was conducted after adjusting for potential confounders, and showed the risk for NMSC in the group exposed to HCTZ was significantly higher than that of the unexposed group (hazard ratio = 1.48; 95% CI 1.03-2.13). In the subgroup analysis, the oldest age group (>= 70 years) showed increased cumulative incidence of NMSC with statistical significance compared with the unexposed control group (log-rank P < 0.01). Conclusions In this study, we revealed that the cumulative use of HCTZ (>= 2500 mg) could increase the risk of NMSC in Koreans, especially the older age group. Thus, HCTZ could be a risk factor for NMSC in East Asian as well as white populations.