Background:Hydroxychloroquine (HCQ) is commonly used for the treatment of various autoimmune diseases. The medication is generally well-tolerated. However, long-term use after 5 years may increase the risk of retinopathy. One study in 2014 has demonstrated the risk can be as high as 7.5%. Optical Coherence Tomography (OCT) has become a major modality in screening retinopathy.Objectives:To evaluate the prevalence of retinal toxicity among patients using hydroxychloroquine and to determine various risk factors associated with hydroxychloroquine-associated retinal toxicity.Methods:We performed a retrospective chart review on a cohort of adult patients with long-term use (≥ 5 years cumulative) of HCQ between January 1st, 2011 to December 31st, 2018 from the Kaiser Permanente San Bernardino County and Riverside medical center areas in Southern California, USA. Patients were excluded if they had previously been diagnosed with retinopathy prior to hydroxychloroquine use, were deceased, or had incomplete OCT exam. Our primary endpoint was the prevalence of patients who developed retinal toxicity detected by OCT, and later confirmed by retinal specialist. Potential risk factors (age, duration of therapy, daily consumption per actual body weight, cumulative dose, confounding diseases and medication) for developing retinopathy were also evaluated. Univariable and multivariable logistic regression analyses were used to determine risk factors associated with retinal toxicity.Results:Among 676 patients exposed to more than 5 years of HCQ, the overall prevalence of retinal toxicity was 6.8%, and ranged from 2.5% to 22.2% depending on the age, weight-based dosing, duration of use and cumulative dose. Duration of therapy for 10 years or more increased risk of retinopathy by approximately 5 to 19 folds. Similarly, weight-based dose of 7 mg/kg/day or greater was assciated with increased risk of retinopathy by approximately 5 times. Patients with cumulative dose of 2000 grams or more had greater than 15 times higher risk of developing retinopathy. Duration of use for10 years or more (odd ratio 4.32, 95% CI 1.99 – 12.49), age (odd ratio 1.04; 95% CI 1.01 - 1.08), cumulative dose of more than 1500 g (odd ratio 7.4; 95% CI 1.40 – 39.04) and atherosclerosis of the aorta (odd ratio 2.59; 95% CI, 1.24 – 5.41) correlated with higher risk of retinal toxicity.Conclusion:The overall prevalence of retinopathy was 6.8%. Regular OCT screening, especially in patients with hydroxychloroquine use for more than 10 years, daily intake > 7 mg/kg, or cumulative dose > 1500 grams is important in detecting hydroxychloroquine-associated retinal toxicityReferences:[1]Hobbs HE. Sorsby A, & Freedman A. Retinopathy Following Chloroquine Therapy. The Lancet. 1959; 2(7101): 478-480.[2]Levy, G. D., Munz, S. J., Paschal, J., Cohen, H. B., Pince, K. J., & Peterson, T. Incidence of hydroxychloroquine retinopathy in 1,207 patients in a large multicenter outpatient practice. Arthritis & Rheumatism: 1997; 40(8): 1482-1486.[3]Ding, H. J., Denniston, A. K., Rao, V. K., & Gordon, C. Hydroxychloroquine-related retinal toxicity. Rheumatology. 2016; 55(6): 957-967.[4]Stelton, C. R., Connors, D. B., Walia, S. S., & Walia, H. S. Hydrochloroquine retinopathy: characteristic presentation with review of screening. Clinical rheumatology. 2013; 32(6): 895-898.[5]Marmor, M. F., Kellner, U., Lai, T. Y., Melles, R. B., & Mieler, W. F. Recommendations on screening for chloroquine and hydroxychloroquine retinopathy (2016 revision). Ophthalmology. 2016; 123(6): 1386-1394.[6]Melles, R. B., & Marmor, M. F. The risk of toxic retinopathy in patients on long-term hydroxychloroquine therapy. JAMA ophthalmology. 2014; 132(12): 1453-1460.Disclosure of Interests:None declared
Persistence of ryegrass, tall fescue and cocksfoot following sequential annual sowings: pasture yield, composition and density in 3 establishment years under sheep grazing in Canterbury
