LONG term users of hydroxychloroquine are at greater risk of permanent visual loss than used to be thought, leading to a call for the development of Australian screening guidelines for hydroxychloroquine retinopathy.
Writing in the Medical Journal of Australia, authors from the University of New South Wales, Sunshine Coast University Hospital, and Liverpool Hospital in Sydney, wrote that previous research which had estimated the prevalence of hydroxychloroquine retinopathy at between 0.5 and 2.0% was “a large underestimation”, and according to more recent studies was more like 7.5%.
“Owing to its efficacy in treating a variety of inflammatory and dermatological conditions (eg, systemic lupus erythematous), cost-effectiveness and relatively good safety profile, hydroxychloroquine is widely used by many Australians long term,” wrote Sonido and colleagues.
“In 2015, there were about 28 300 individuals (0.12% of all Australians) using the drug daily.
“Given this estimated number of users and the 7.5% prevalence rate, there could be more than 2000 potential cases of hydroxychloroquine retinopathy in Australia.
“However, there is no recommended consensus on screening for this condition in Australia, which may lead to inconsistent screening and missed cases.”
Two main guidelines exist for hydroxychloroquine retinopathy – one from the US, and one from the UK.
“Both guidelines recommend that patients who fall within the high-risk category should commence screening earlier than the general population, who are screened starting from 5 years of taking hydroxychloroquine,” Sonido and colleagues wrote.
“However, there is some disagreement on which risk factors warrant classification into the high-risk category. Recommendations also vary regarding the frequency of screening in high-risk patients.”
Australian guidelines are important because “compared with the US and the UK, Australia has a significantly larger proportion of residents identifying as Asian in ancestry”.
“Due to the more peripheral pattern of damage from hydroxychloroquine sometimes seen in Asian populations, there are recommendations that a wider 24-2 or 30-2 visual field test should be performed for such patients, in addition to the recommended 10-2 visual field test in the US and UK guidelines,” wrote Sonido and colleagues.
“Another factor to consider is whether Australia’s public health system can support ophthalmology screening at the frequency recommended by the US and UK guidelines.
“Already, waiting times for non-urgent appointments for ophthalmologists in the public system can reach years.
However, before guidelines can be established, Sonido and colleagues concluded, “more research needs to be conducted on the prevalence and current detection rates of hydroxychloroquine retinopathy in Australia”.
- Cate Swannell