Background/Purpose: Hydroxychloroquine (HCQ) is used widely for the treatment of inflammatory arthritides and systemic lupus erythematosus. Recent publications have shown that HCQ toxicity is not as rare as previously thought among long-term users of the drug, with overall prevalence in a large demographic study around 7.5%. The risk of toxicity was greatly dependent on daily dose. Furthermore, HCQ retinopathy is not reversible and cellular damage may progress even after the drugs are stopped. The purpose of our study was to determine whether appropriate HCQ dosing and toxicity screening is elicited during regular clinical encounters for patients with inflammatory arthritis and connective tissue diseases.

Methods: A prospective clinical audit was conducted at nine Canadian rheumatology practices in eastern Ontario. Audit standards were based on the American College of Rheumatology (ACR) and American Academy of Ophthalmology (AAO) recommendations. Best practice standards included appropriate weight based dosing of hydroxychloroquine and subsequent monitoring for toxicity. We audited 100 appropriate patient encounters, spread out over nine practices using a standardized screening form.

Results: Among the 100 patients enrolled in the study, 80% were female with an average age of 58 years. Patients were on hydroxychloroquine for an average duration of 73 months, with rheumatoid arthritis (61%) and systemic lupus erythematosus (23%) being the most common diagnoses as per the ACR classification criteria. A total of 62 patients were considered high risk for retinal toxicity based on AAO criteria including age, duration of use, renal or liver dysfunction and pre-existing retinal disease.

Three out of four audit standards were not met. No patients in our audit had hydroxychloroquine retinopathy and therefore, the last standard could not be assessed. Only 70% of patients were being appropriately dosed based on body weight. Furthermore, 17% of patients were on a prescription dose that was greater than 10% of the recommended dosage. Only 87% of patients had a baseline ophthalmologic exam in the first year of treatment, while guidelines suggest all patients should have one. Within the hydroxychloroquine retinopathy high-risk cohort, only 91% of patients were getting yearly eye exams.

Conclusion: Our guideline-based standards of appropriately dosing hydroxychloroquine and monitoring for retinopathy are not being met in typical patient encounters. The current system can be improved and the next step is to provide clinicians with a weight-based dosing chart that includes monitoring requirements. This intervention will be applied over three months and a re-audit will be conducted. The results will be compared to pre-intervention outcomes.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/clinical-audit-of-hydroxychloroquine-dosing-and-toxicity-screening-in-patients-with-inflammatory-arthritis-and-connective-tissue-diseases/