Incidence of and risk factors for chloroquine and hydroxychloroquine retinopathy in Thai rheumatologic patients

OBJECTIVE To study the incidences of and risk factors for chloroquine (CQ) and hydroxychloroquine (HCQ) retinopathy in Thai rheumatologic patients. METHODS A retrospective cohort study of 234 rheumatologic patients receiving either CQ or HCQ was conducted. Patients were divided based on whether or not they developed retinopathy as retinopathy-positive or negative groups. Medical records giving details regarding age, gender, body weight, underlying diseases, daily doses, and cumulative doses of CQ or HCQ were reviewed. CQ and HCQ retinopathy were diagnosed by indirect ophthalmoscopy, Humphrey visual field test, and optical coherence tomography. The main outcome measures were incidences and risk factors of CQ and HCQ retinopathy. RESULTS The CQ retinopathy was detected in 14 of 173 patients (8.09%) who received CQ for 139-2,033 days, cumulative doses from 14.3 to 325.1 g, and daily doses from 0.8 to 18.5 mg/kg/d. Their ages ranged from 27 to 65 years. When compared to the CQ retinopathy-negative group, only age, body weight, and cumulative dose showed statistically significant differences. The HCQ retinopathy-positive group was comprised of 2 of 61 patients (3.28%) who received HCQ for 660-828 days, cumulative doses from 80 to 130 g, and daily dose from 1.9 to 4.4 mg/kg/d. Their ages were 36 and 39 years. Compared to the HCQ retinopathy-negative group, there were no statistically significant differences in studied risk factors. CONCLUSION Incidences of and risk factors for CQ and HCQ retinopathy were reported. Since most patients developed retinopathy earlier than 5 years, it is suggested that patients taking long-term CQ or HCQ should undergo ophthalmologic screening annually after the baseline examination.