Background: Hydroxychloroquine (HCQ) has been proven effective in several immune mediated diseases. Long-term use of HCQ is very common in patients with systemic autoimmune disease. The greatest advantage of HCQ is that it may reduce the risk of flares and thereby allow glucocorticoid dose reduction. The risk/benefit ratio of HCQ is excellent but HCQ is also known for its potentially severe and fortunately rare side effect: retinal toxicity. In The Netherlands, there are no standard guidelines regarding the dosing of HCQ and ophthalmologic screening of HCQ-induced complications. The American Academy of Ophthalmology (AAO) has recently published their revised recommendations on screening and dosing of HCQ. Risk of retinal toxicity is mainly determined by the two most significant risk factors: daily dose of HCQ (mg/kg/day) and duration of HCQ therapy (years). The AAO recommends a maximum daily HCQ dosage of <5.0 mg/kg real weight, to reduce the risk of toxicity.^{Marmor, 2016}

Objectives: To raise more attention for the revised recommendation of the AAO, our patient organisation started an online survey asking patients with (systemic) autoimmune diseases which dose of HCQ (mg) they take on a daily basis.

Methods: Patients in the Netherlands were given the opportunity to complete the online survey at the website of the NVLE (Dutch patient association for people with Lupus Erythematosus, Anti-Phospholipid Syndrome, Systemic Sclerosis and Mixed Connective Tissue Disease) from July 26th – November 18th, 2017. The promotion of the survey took place solely through Social Media with a link to the survey. A total of 24 questions had to be filled in to complete the survey. Each individual was asked to write down their real weight (kg) for calculating the daily HCQ dosage (mg/kg/day).

Results: A total of 705 individuals completed the online survey. The daily dosage (mg/kg/day) was available from 645 patients. The majority were females (n=645) and diagnosed with (systemic) lupus erythematosus (n=518). The average dosage of HCQ was 4,50±1,68 mg/kg/day. The daily dosage of 5 mg/kg was exceeded by 258 of the patients (40%). Eighty-one individuals (12.6%) used a daily dosage of ≥5 mg/kg for more than 10 years. The most reported HCQ-induced complications were gastrointestinal complaints (n=55), problems with vision (n=43), and nausea (n=32).

Conclusions: Patients (and prescribing physicians) should be informed about risk of toxicity, proper dose levels, and the importance of regular annual screening. Physicians prescribing HCQ must aim for a daily HCQ dosage of less than 5.0 mg/kg/day, especially for patients using HCQ for already more than 10 years. (Inter)national guidelines regarding the screening and dosing of HCQ should be provided by the authorities to secure patient safety and reduce the frequency of (severe) retinal complications.

Reference:

1. Michael F, Marmor, et al. Recommendations on Screening for Chloroquine and Hydroxychloroquine Retinopathy (2016 Revision). Ophthalmology 2016;123(6):1386–94.

Acknowledgements: We would like to thank prof. dr. Frank van den Hoogen for his advice and dr. Els van de Ende for reading our abstract.

Disclosure of Interest: None declared

DOI: 10.1136/annrheumdis-2018-eular.2495