Background/Purpose:

Hydroxychloroquine (HCQ) is a widely-used medication in many rheumatologic conditions. The most worrisome toxicity is irreversible damage to retinal pigment epithelium which can lead to blindness. The most recent 2016 guidelines from the American Academy of Ophthalmology (AAO) recommend the dose of HCQ ≤5 mg/kg real body weight to minimize toxicity¹. According to these new guidelines, the risk of HCQ retinal toxicity is less than 1 % in the first year of therapy and less than 2 % up to 10 years of therapy. There is an increased risk of HCQ retinopathy with increase in the cumulative dose. Per the prior 2011 AAO guidelines the recommended maximum dose to minimize HCQ retinal toxicity was 6.5 mg /kg based on ideal body weight². The advantage of the real body weight formula is that it distributes the risk evenly on a broad range of body habitus.

Methods:

We identified, patients on HCQ in year 2016 at VA Connecticut Health Care System. Primary outcome was to identify patients whose dose exceeded the maximum recommended dose as per the 2016 guidelines. Data on indications for medication use, dose, ideal weight, real weight, duration of therapy and adherence to the last 3 years screening ophthalmologic exams were obtained. We also looked at the number of patients who were discontinued from HCQ use due to retinal toxicity.

Results:

There were 102 patients who were prescribed HCQ in the year 2016. 89 patients were actively on HCQ. The average age was 64.7; (69/89) were male. 46/89 had RA. 12/89 had SLE. Other diseases included ScLE, MCTD, UCTD, Sjogren’s syndrome, hepatitis C related arthritis. 45/77 of patients had 3 ophthalmology screening in past 3 years for toxicity. The average duration of HCQ use varied from <1 year to 20 years. There were 19/89 (21.3%) patients who were receiving more than 5 mg/kg/day of HCQ. HCQ was discontinued in one patient due to HCQ retinal toxicity during the observation period. He had been on HCQ for 13 years.

Conclusion:

Our study revealed, 19/89 (21.3%) patients who were receiving more than currently recommended daily doses of HCQ based on the 2016 AAO guidelines potentially placing them at increased risk for HCQ retinal toxicity. With the new guidelines for HCQ dosing it becomes imperative for rheumatologists to assess the weight of their patients and adjust the dose of HCQ downward if the patient weights <80 kg.

References:

1. Recommendations on Screening for Chloroquine and Hydroxychloroquine Retinopathy (2016 Revision). Marmor MF, Kellner U, Lai TY, Melles RB, Mieler WF; American Academy of Ophthalmology.

2. Revised recommendations on screening for chloroquine and hydroxychloroquine retinopathy. 2011 Marmor MF, Kellner U, Lai TY, Lyons JS, Mieler WF; American Academy of Ophthalmology.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/new-guidelines-on-hydroxychloroquine-dosage-where-are-we/