26 October 2021
With hydroxychloroquine (HCQ) efficacy, dosing and retinopathy being a topic of wide interest to the profession we partnered with Blackrock Pharmaceuticals to deliver an educational webinar to support members' learning. Prof Chris Edwards, University Hospital Southampton, Dr James Galloway, King’s College London and Dr Imran Yusuf, University of Oxford and Oxford Eye Hospital, presented the current thinking.
The need for HCQ in rheumatology
Prof Edwards summarised the data supporting the continued major role of HCQ in lupus and in combination therapy in rheumatoid arthritis (RA). The audience was asked how concerned they were about HCQ retinopathy, and the majority (58%) were either very concerned (9%) or a little concerned (49%).
He said that issues might arise if the retinopathy issue put rheumatologists off using HCQ: “What we want to avoid is; no use in RA and underdosing in lupus, such that stronger drugs need to be used sooner... unnecessarily”.
How big is the problem of hydroxychloroquine retinopathy?
Dr Yusuf explained that advances in OCT retinal imaging technology in the 1990s transformed the ability to detect HCQ retinopathy before symptoms were present. The condition, first identified in 1963, previously considered rare (0.5% in long-term users) was shown to be approximately 14 times more common than previously thought (7.5%).
In 2016, Melles and Marmor showed that, depending on dose and duration of therapy, retinopathy can increase to 20-50% after 20 years of therapy, especially at doses >5mg/kg/day. The impact on patients can be devastating and in addition to the psychological impact, driving, reading and employment can all be affected.
Reducing the risk of retinopathy – guidelines
81% of the audience currently follow the RCOphth HCQ dosing and retinopathy guidelines. Despite this, only 61% reported that their hospital ophthalmology service supported screening for HCQ retinopathy. To help address this challenge, the latest update in December 2020 simplified the screening guidance in two important ways:
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Baseline testing for new initiators of HCQ is no longer recommended
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The testing protocol was amended to increase the efficiency of monitoring, with those patients for whom retinal imaging tests (OCT and FAF) are normal, no longer requiring further investigation in that year
Weight-based dosing and the ‘5x5’ rule
The guideline update confirmed the ‘5x5’ rule (ideally keep dosage < 5mg/kg/day and monitor, annually after five years of drug use). Retinopathy risk increases for patients on doses of HCQ >5mg/kg/day, taking concomitant tamoxifen or with renal impairment. For these patients, annual screening should occur from one year onwards.
The audience was asked to share their approach to HCQ dosing. Only 28% still used a loading dose and most (81%) followed weight-based approaches (67% used 5mg/kg/day actual body weight and 14%, 6.5 mg/kg/day ideal body weight). With increased focus on the accuracy of weight-based dosing, the audience was asked what approach they took when patients required a maintenance dose in between 200mg and 400mg. The majority (69%) used alternate day dosing 400mg/200mg. Only 28% were aware of a HCQ 300mg tablet now being available and 8% responded that they currently prescribed it in this situation.
Watch webinar