Screening for hydroxychloroquine retinopathy in Australia

The large number of long term hydroxychloroquine users in Australia necessitates clear guidelines on hydroxychloroquine retinopathy screening

Hydroxychloroquine retinopathy, which causes permanent visual loss, is a well documented adverse effect in long term users of both hydroxychloroquine and chloroquine. However, it can be difficult to detect as visual acuity is often well preserved until the disease is severe.1 Because of this, it was once thought to be a rare adverse effect, with only 0.5–2.0% of long term hydroxychloroquine users estimated to suffer from the condition.2 However, a 2014 epidemiological study of 2361 patients using hydroxychloroquine long term in the United States found that this was a large underestimation.2 The investigators found an overall prevalence of 7.5% in patients who had taken the drug for at least 5 years, but this risk increased with length of use and dosage.2

Owing to its efficacy in treating a variety of inflammatory and dermatological conditions (eg, systemic lupus erythematosus), cost‐effectiveness and relatively good safety profile, hydroxychloroquine is widely used by many Australians long term.3 In 2015, there were about 28 300 individuals (0.12% of all Australians) using the drug daily.4 Given this estimated number of users and the 7.5% prevalence rate,2 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.5

Existing screening guidelines

Currently, two main guidelines on hydroxychloroquine retinopathy screening exist and are used by practitioners in Australia: the American Academy of Ophthalmology 2016 guidelines and the United Kingdom Royal College of Ophthalmologists 2020 guidelines.1,6 While both are very similar, small but significant differences exist between them.

For example, 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.1,6 However, there is some disagreement on which risk factors warrant classification into the high risk category (Box 1). Recommendations also vary regarding the frequency of screening in high risk patients.1,6

There are also small differences in the investigations recommended by each set of guidelines. For example, the UK guidelines6 recommend fundus autofluorescence as an additional standard screening investigation (Box 2).

The need for Australian guidelines

There are currently no studies discussing the prevalence of hydroxychloroquine retinopathy in Australia, which makes it difficult to determine whether current screening practices are sufficient. However, the differences in the US and UK guidelines may have practical consequences for the consistency of hydroxychloroquine detection rates in the Australian population.5

As these guidelines were developed in non‐Australian settings, they may also need to be modified to better suit Australia’s unique context. For example, compared with the US and the UK, Australia has a significantly larger proportion of residents identifying as Asian in ancestry. In 2016, about 13% identified as having Asian ancestry,7 compared with 5.9% of Americans who identified as Asian in 2019.8 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.9

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. In South Australia, the median waiting time for an outpatient ophthalmologist appointment ranges from 4.8 to 17.6 months at metropolitan hospitals,10 which makes annual screening impossible for many patients without private care. The costs to the health system also warrant consideration. Under the current Medicare Benefits Schedule, a standard specialist consultation (item 104) and visual field test (item 11224) would cost $131.65, totalling more than $1.5 million to test 50% of the individuals taking hydroxychloroquine annually in the public setting.11 Australia‐specific screening guidelines could better account for these practical considerations, although further studies would be necessary to determine how successfully the system already supports hydroxychloroquine retinopathy screening based on existing guidelines.

Conclusion

Given its potential to cause permanent vision loss and the number of Australians taking hydroxychloroquine long term, developing Australian screening guidelines for hydroxychloroquine retinopathy would be beneficial in promoting consistent screening practices tailored to the Australian population. Before these can be established, however, more research needs to be conducted on the prevalence and current detection rates of hydroxychloroquine retinopathy in Australia.