Background/Purpose: Hydroxychloroquine (HCQ) is a commonly prescribed medication for systemic lupus erythematosus (SLE), rheumatoid arthritis (RA) and other rheumatic diseases. However, HCQ may cause retinal toxicity leading to permanent vision loss. The risk of HCQ-related retinopathy correlates with both daily dose and duration of use¹.  In addition to screening ophthalmologic examinations, the most recent guidelines by the American Academy of Ophthalmology recommend limiting the dose of HCQ to 5mg/kg/day of actual body weight¹. The goal of this study was to determine the proportion of patients in our practice receiving HCQ in compliance with these recommendations.

Methods: We performed a single-center retrospective analysis of 1066 adult patients receiving HCQ for SLE or RA in our rheumatology practice at Beth Israel Deaconess Medical Center between January 1, 2018 and December 1, 2018. To account for “loading dose” adjustments just after beginning the medication, we included only patients who had two rheumatology provider interactions separated by at least 6 months. For patients who stopped taking the drug, the reason for discontinuation was noted but these patients, patients who were lost to follow up, and those who died during the period of study were excluded from the dosing analysis. For each provider interaction, we collected the patient’s HCQ dose and weight. We used this data to calculate the daily weight-based dose at each time point.

Results: 830 patients met inclusion criteria:  of these, 181 (22%) had weight-based doses above the current recommended dose of 5mg/kg/day.  35 (4%) patients had doses above 6.5mg/kg/day (a cut-off suggested by older guidelines). Of the 81 patients who discontinued HCQ during the period of study, the most commonly cited reasons for discontinuation were medication ineffectiveness (27%), de-escalation of therapy (19%), gastrointestinal side effects (14%), and retinal changes (6%).

Conclusion: At least 2 years after the publication of updated HCQ dosing guidelines, 22% of our patients were taking a dose that was higher than recommended by current guidelines. Further analysis is underway to understand the reason(s) for these finding and to provide feedback that may lead to higher compliance.  In addition, we hope to study the impact of these new guidelines on retinal toxicity and the effectiveness of HCQ within our practice.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/adherence-to-weight-based-dosing-guidelines-in-patients-receiving-hydroxychloroquine-for-rheumatoid-arthritis-and-systemic-lupus-erythematosus/