Response to comment on “Hydrochlorothiazide use and the risk of skin cancer in patients with hypertensive disorder: a nationwide retrospective cohort study from Korea”

Associations of thiazide use with skin cancers: a systematic review and meta-analysis

“…Our study indicated an increased risk for NMSC associated with the use of hydrochlorothiazide but not with bendroflumethiazide or indapamide. Specifically, we found a higher risk for SCC than for BCC associated with thiazide use, consistent with evidence that cumulative UV exposure plays a greater role in the aetiology of SCC than of BCC [ 35 , 36 ]. The minimum average daily UV exposure level to induce skin cancers among thiazide users is unclear; however, one Icelandic study indicated that relatively low levels of average daily UV exposure were sufficient to cause 1.24-fold and 1.14-fold increases in the risks of SCC in situ and BCC, respectively, following hydrochlorothiazide use [ 13 ].…”

“…The studies with overlapping populations and selections of studies in the main analyses are presented in Additional file 1 : Table S2. In addition, one cohort study with immortal time bias highlighted in a commentary written by Pottegård et al was excluded [ 33 – 35 ]. Briefly, because hydrochlorothiazide was less likely to be prescribed as the drug of choice for antihypertensive treatment, following up patients from the first date of hydrochlorothiazide may lead to a spurious protective effect against skin cancers because participants were free from the outcome of skin cancer (i.e., immortal time) until they received hydrochlorothiazide.…”