Exposure to sunlight and fair skin type are the main risk factors for the development of skin cancer. Recent studies have raised concerns that the use of thiazides and thiazide-like diuretics (TZs) as a group, the drug hydrochlorothiazide in particular, is also associated with an increased risk of skin cancer. TZs are mainly used to treat high blood pressure and swelling due to fluid build-up. To increase their effectiveness, TZs are often combined with other blood pressure medications as a single pill. If TZs increased the risk of skin cancer, there would be far-reaching consequences due to their widespread use worldwide. However, data on this potential association are not only limited but also inconsistent. Using the Clinical Practice Research Datalink (CPRD), we plan to investigate whether patients who take TZs are at an increased risk of developing skin cancer. This study will give doctors and patients more information about the benefits and harms of TZs in order to make informed decisions about their use.
Exposure to thiazides and thiazide-like diuretics (TZs), known as photosensitizing agents, has recently been associated with an increased risk of cutaneous malignant melanoma (CMM) and nonmelanoma skin cancer (NMSC; in particular of basal cell carcinoma [BCC] and cutaneous squamous cell carcinoma [SCC]). However, data on this potential association are not only limited but also inconsistent.
We will conduct a cohort study to estimate the absolute and relative risks of CMM, BCC, and SCC in TZs users compared with patients taking a) calcium channel blockers (CCBs) and separately b) renin-angiotensin-aldosterone system inhibitors (RAASi), two other classes of first-line antihypertensive drugs.
We will estimate incidence rates of skin cancer (CMM, BCC, and SCC) in patients with short-term or long-term exposure to TZs as well as in patients with short-term or long-term exposure to a) CCBs and b) RAASi. We will then calculate incidence rate differences (RDs) and incidence rate ratios (IRRs) with 95% confidence intervals (CIs) adjusted for several confounders to quantify the risk of skin cancer associated with exposure to TZs, compared with exposure to a) CCBs and b) RAASi.
These data will provide clinicians additional data to weigh the benefits and harms of TZ use in their patients.
Diagnosis (recorded as Read codes) of:
- CMM and/or
- NMSC (specifically BCC or SCC) in the CPRD
Susan Jick - Chief Investigator - BCDSP - Boston Collaborative Drug Surveillance Program
Daphne Reinau - Corresponding Applicant - University of Basel
- Collaborator -
Christoph Meier - Collaborator - University of Basel
Rahel Schneider - Collaborator - University Hospital Basel
Seline Stoffel - Collaborator - University Hospital Basel
Christoph Meier - Collaborator - University of Basel
Julia Spoendlin - Collaborator - University of Basel
HES Admitted Patient Care