Sharp decline in hydroxychloroquine dosing-analysis of 17,797 initiators from 2007 to 2016

We aimed to assess the impact of ophthalmology weight-based hydroxychloroquine (HCQ) dosing guidelines on prescribing patterns. We examined initial HCQ prescription dosing between 2007 and 2016 and determined independent predictors for HCQ dosing above the previous (2011) recommended ≤ 6.5 mg/kg of ideal body weight (IBW)/day and the latest (2016) recommended ≤ 5.0 mg/kg of actual body weight (ABW)/day using logistic regression. Among 17,797 patients (82% female), the proportion of 400 mg prescribed daily dosing declined sharply from 80% in 2007-2011 to nearly 40% in 2014, whereas the proportions of 200- and 300-mg daily doses showed the opposite trends during the same periods. Accordingly, the risk of HCQ dosing above the guideline recommendations declined by more than 60%. While 36% of normal body mass index (BMI) individuals were classified as dosing above the IBW-based guideline, 66% would have received dosing above the latest ABW-based guideline. The risk of excess dosing was associated with female patients and dermatology prescribers (adjusted odds ratios ≥ 2 according to IBW- or ABW-based guidelines). There has been a sharp decline in HCQ dosing following ophthalmology weight-based guidelines in recent years. While this trend is likely helpful in reducing the risk of retinopathy, its potential impact on HCQ efficacy remains to be clarified.