Background/Purpose: Hydroxychloroquine (HCQ) is commonly used as a disease-modifying anti-rheumatic drug (DMARD) for patients with rheumatoid arthritis (RA). HCQ has previously been the subject of interest for its in-vitro antiviral activity against influenza A strains, although in-vivo studies have yielded conflicting results. There has recently been renewed interest in the use of HCQ as prophylaxis and treatment for respiratory viral infections. Patients with RA are known to have increased risk of influenza infections and influenza-associated hospitalizations. They thus potentially provide the opportunity to explore the antiviral effects of HCQ. Our study aims to examine the association of HCQ use among RA patients with hospital inpatient admissions for influenza.

Methods: We examined general medical inpatient admissions for patients with a diagnosis of RA in a large tertiary hospital between January 2014 and December 2018. Natural language processing, ICD-10 codes, and medical record review were utilized to determine patient demographic data (age, gender, and smoking history), medical diagnosis, and medication use. Major confounders (smoking status, chronic obstructive pulmonary disease (COPD), age, gender, and other DMARD use) were selected. DMARD use was defined as medical record documentation of use at time of admission. Multivariate logistic regression models were used to assess the association of HCQ use and inpatient admission for influenza. The strength of association was assessed using adjusted odds ratios (OR) and associated 95% confidence intervals (CI).

Results: From 909 inpatient admissions during the study period, 23 admissions were primarily for influenza. There were no statistical differences in patient demographics or DMARD medication between the two groups (Table 1). A total of 265 (30%) non-influenza admissions and 9 (39%) influenza admissions used HCQ at time of admission. In our multivariate regression model, HCQ use among patients with RA was not associated with a statistically significant difference in inpatient admission for influenza when adjusted for confounders (OR 1.45, CI 0.58 – 3.59).  Likewise, the lack of association was persistent when adjusted for methotrexate (OR 1.42, CI 0.58 – 3.50) and corticosteroid use (OR 1.40, CI 0.56 – 3.54).

Conclusion: There was no association in our cohort to support the contention that HCQ use prevents inpatient admission for influenza among RA patients, and in fact may even favour the possibility of increased risk. This study contributes to the growing evidence that HCQ does not confer a protective effect for respiratory viral infections.

Table 1: Characteristics of rheumatoid arthritis patients admitted for influenza compared to those admitted for other indications.

ACR Meeting Abstracts - https://acrabstracts.org/abstract/hydroxychloroquine-is-not-associated-with-reduced-influenza-admissions-in-rheumatoid-arthritis-patients/