Association between Hydroxychloroquine and bacterial pneumonia in rheumatic patients: A population‐based propensity score matching cohort study

Background Whether hydroxychloroquine (HCQ) use could reduce lesser risk of bacterial infections is unknown. We aimed to conduct a retrospective cohort propensity-matching study to investigate the association between HCQ use and the incidence of bacterial pneumonia in rheumatic patients. Methods The Longitudinal Health Insurance Database (LHID) from Taiwan National Health Insurance Research Database (NHIRD) of 23 million Taiwanese populations was used. We included patients who were newly diagnosed with rheumatic and immune disease (ICD-9-CM codes 696.0, 710, 714) within 2000-2012. HCQ users and non-users were then matched according to age, sex, urbanisation level, monthly income, comorbidities and medications in the ratio of 1:1 by the propensity score matching. Cox proportional hazard model was used to evaluate the risk of bacterial pneumonia in rheumatic patients who used HCQ and who did not use HCQ. Results There were total 3285 patients with rheumatic and immune disease enrolled. The cumulative incidence curve of patients with the use of HCQ sulphate had no difference to that of patient without the use of HCQ sulphate in propensity score-matched cohort, (Log-rank test: P = .5). However, patients who used HCQ sulphate for more than 1400 average use days had a lesser risk of bacterial pneumonia (adjusted HR = 0.55, 95% CI = 0.35, 0.89) in the cohort matched, with regarding HCQ non-users as a reference. Conclusion Rheumatic patients taking HCQ had no overall significant differences of bacterial pneumonia incidences compared with rheumatic patients not taking HCQ. HCQ used more than >1400 days or lupus patients using HCQ was associated with lower risk of bacterial pneumonia.