AB1393 HYDROXYCHLOROQUINE (HCQ) BLOOD LEVEL AS AN ADDITIONAL RISK FACTOR IN PATIENTS WITH A HIGH RISK OF DEVELOPING HCQ RETINOPATHY IN THE ASIAN POPULATION: A CASE-CONTROL STUDY IN A TERTIARY CENTER
Authors: T. W. Chang, T. T. Lai, G. Y. Chen, T. Y. Lan, J. H. Kao, T. J. Lee, K. Y. Lin, S. C. Hsieh, K. J. Li
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> Hydroxychloroquine retinopathy (HCQR) is an uncommon but severe complication resulting from the prolonged use of hydroxychloroquine (HCQ). The most predictive risk factors for HCQR are still not clearly understood, with a particular lack of comprehensive studies in Asian populations. <h3>Objectives:</h3> This study aims to identify risk factors associated with HCQR in autoimmune disease patients who have been exposed to HCQ for prolonged periods. <h3>Methods:</h3> In this single-center case-control study, participants were selected based on specific criteria: minimum three years of HCQ use, a daily HCQ dose of 400 mg, and undergoing at least one ophthalmologic examination for HCQR. Diagnosis of "definite HCQR" was determined by a retinal specialist according to 2020 guidelines from The Royal College of Ophthalmologists, UK. Additionally, blood levels of HCQ and its metabolites in patients were determined by using liquid chromatography-tandem mass spectrometry (LC-MS/MS). <h3>Results:</h3> The study involved 76 participants, comprising 19 HCQR patients and 57 controls. Most patients were female (90.8%), with a median age of 50 years (interquartile range [IQR] 40-63) and median weight of 54 kg (IQR 48-62). The median duration of HCQ exposure was 11.7 years (IQR 9.3-13.8), and the median cumulative dose was 1,599 g (IQR 1,311-1,950). Key variables, including age, weight, HCQ exposure duration, and cumulative dose were similar across both groups. However, HCQR patients showed higher white blood cell counts (p=0.039) and marginally higher estimated glomerular filtration rates (eGFR) (p=0.060). Notably, HCQR patients exhibited significantly higher levels of HCQ and desethylchloroquine (DCQ) (p=0.004 and p=0.028, respectively), with a greater proportion having HCQ blood levels exceeding 1,000 ng/mL (84% versus 44%, p=0.002) or 750 ng/mL (95% versus 68%, <i>p</i>=0.030) (Table 1). Univariate logistic regression identified significant correlations between HCQR and variables like height (OR 0.911, 95% CI 0.830-0.999), and HCQ blood level &gt;1,000 ng/mL (OR 6.827, 95% CI 1.788-26.059). Multivariate logistic regression, adjusted for confounders, retained the significance of HCQ blood level &gt; 1,000 ng/mL (Adjusted OR 5.965, 95% CI 1.482-24.009) (Table 2). <h3>Conclusion:</h3> In Asian patients at high risk for HCQR due to long-term exposure and higher doses of HCQ, HCQ blood level greater than 1,000 ng/mL appears to be an additional risk factor. These findings provide crucial insights for the management and monitoring of patients on prolonged HCQ therapy. <b>Table 1.</b> Characteristic of patients according to the result of HCQR and the level of HCQ <b>Table 2.</b> Univariate and multivariate logistic regression analyses <h3>REFERENCES:</h3> [1] Yusuf IH 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. [2] Füzéry AK et al. A rapid and reliable method for the quantitation of hydroxychloroquine in serum using turbulent flow liquid chromatography-tandem mass spectrometry. Clin Chim Acta. 2013 Jun 5;421:79-84. <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> <b>None declared.</b>