Ab1341 Hydroxychloroquine Monitoring- Retinal Toxicity Rates and Service Challenges

Background: Hydroxychloroquine (HCQ) is widely used in the management of autoimmune conditions. The risk of ocular toxicity, leading to conditions such as retinopathy and irreversible vision impairment, is estimated to affect up to 7.5% of patients who use HCQ for more than 5 years. However, there is significant variation in screening recommendations and toxicity rates reported across UK, Europe and America. In 2020 the UK guidelines [1] regarding toxicity monitoring updated the 2018 recommendation for the need of a baseline optical coherence tomography (OCT) scan, unless there are additional risk factors that would increase toxicity. Known risk factors include high-dose of HCQ (>5mg/kg/day); concurrent tamoxifen use; impaired renal function; chloroquine use; age>65 and long duration of treatment for >5 years. The major change to the guideline driven by real-world outcomes of monitoring, helped alleviate pressures on ophthalmology/rheumatology services. However the balance between appropriate referrals for toxicity screening and availability within the National Health Service capacity remains a challenge. Objectives: The first aim was to ascertain whether our observed incidence of HCQ Retinal toxicity aligns with findings reported in existing literature. Secondly, we sought to determine patient missed attendance for this screening which contributes significantly to service pressures and appointment availability. Methods: We compared all individuals prospectively referred in 2018-19 at a UK secondary care hospital, to a snapshot cohort of patients from 2021-2023 who were referred for screening following the guideline update. We excluded 2020 in view of reduced referrals and capacity due to Covid19. Results: A total of 243 patients were included, of who 234 attended for screening. Some 175 patients were identified from the 2018-2019 period, with 171 patients (98%) attending their appointments. The majority had an inflammatory arthritis n=113 (66%) of who 75 (44%) had RA; whilst 41 (24%) had connective tissue disease (mostly SLE n=17(10%)). Of those, 96 patients had been on HCQ for >5 years, while the rest adhered to the 2018 guidelines for baseline screening. From the 96 patients who took HCQ for >5 years, two exhibited confirmed toxicity. The first one used HCQ for >10 years and the second one for >20 years and was aged >65 years. Consequently, our established toxicity rate is 2.1% for that period. The missed attendance rate for this period was 2.3%. For the snapshot audit from 2021-2023 there were 68 patients reviewed, of who one (1.5%) had confirmed toxicity, with risk factors including age >65, concomitant tamoxifen use and duration of treatment for >10 years. The missed attendance rate for this period was calculated at 7.4%. There was no difference in the toxicity rate picked up in the two periods p>0.05. The overall rates shown in Table 1. During the screening, important non-hydroxychloroquine related ophthalmic pathology was identified in 5% of the patients. Conclusion: The overall rate of toxicity identified through our screening service for 2018-2023 was 1.8% which is significantly lower than reported literature. The change in the UK guidance not to offer baseline screening prior to hydroxychloroquine initiation, has resulted in a reduction of referrals for baseline which may allow more targeted screening. Our overall missed appointment rate was 3.7% indicating that the screening is acceptable and taken up by our patients. REFERENCES: [1] Yusuf I et al. The Royal College of Ophthalmologists recommendations on monitoring for hydroxychloroquine and chloroquine users in the United Kingdom (2020 revision): executive summary. Eye (Lond). 2021 Jun;35(6):1532-1537. DOI: 10.1038/s41433-020-01380-2. Acknowledgements: NIL. Disclosure of Interests: None declared.