Hydroxychloroquine-induced pigmentation in rheumatic diseases: prevalence, clinical features and influencing factors

To describe the clinical features of Chinese patients with HCQ-induced pigmentation and analyse the potential risk factors associated with HCQ-induced pigmentation.

A cross-sectional study was conducted over a duration of 7 months, during which patients who had received HCQ treatment for >6 months were included. Data was collected through a structured questionnaire that encompassed demographic and geographic characteristics, information on HCQ and concomitant medication usage, sun exposure characteristics and hyperpigmentation-related characteristics. Univariate and multivariate analyses were employed to calculate the statistical association between HCQ-induced pigmentation and multiple variables.

Out of 316 patients, 83 (26.3%) patients presented hyperpigmentation during HCQ treatment. Hyperpigmentation was presented after a median duration of HCQ treatment of 12 months (interquartile range, 6.0-30.0 months) with a median cumulative dose of 108 g of HCQ (interquartile range, 36-288 g). The most frequently affected sites of pigmentation were the face (60.2%), lower limbs (36.1%) and hands (20.5%). There was a linear decrease in the incidence of pigmentation with increasing daily sun exposure time (P = 0.030). In the multivariate analysis, variables (cumulative HCQ dose and daily sun exposure time) were included in the final models. The results revealed an independent correlation between HCQ-induced pigmentation and daily sun exposure exceeding 1 h (OR: 0.431; 95% CI: 0.208-0.892; P = 0.023).

The occurrence of HCQ-induced pigmentation is not uncommon, with an incidence rate of 26.3%. Daily sun exposure time exhibited a protective effect against HCQ-induced pigmentation.