Incidence and clinical course of COVID-19 in patients with rheumatologic diseases: A population-based study.

Objectives: Patients with rheumatologic diseases might be more susceptible to COVID-19 and carry a poorer prognosis. The aim of this study is to examine the incidence and outcomes of all COVID-19 patients with rheumatologic conditions in Hong Kong.

Methods: This is a population-based retrospective study. All patients tested positive for SARS-CoV-2 by PCR with a previous diagnosis of rheumatologic diseases were reviewed. The incidence of COVID-19 in patients with rheumatologic conditions was calculated and compared to the general population in Hong Kong. Descriptive data of those rheumatologic patients with COVID-19 and the clinical course of the index infection were presented.

Results: Up till 27 May 2020, there were 1067 cases of COVID-19 diagnosed in Hong Kong which had a population of 7.5 million. Out of the 39,835 patients with underlying rheumatologic diseases, we identified 5 PCR confirmed COVID-19 cases. The estimated incidence of COVID-19 was 0.0126% patients with rheumatologic diseases, compared to 0.0142% in the general population. All 5 patients had inflammatory arthropathies. One patient was on hydroxychloroquine and sulphasalazine, and one was on methotrexate. None of the 3534 patients on b/tsDMARDs was infected. Four patients had leucopenia/lymphopenia and stool viral PCR was positive in 3 patients. All patients made uneventful recovery without complications or flare of underlying diseases.

Conclusions: We found no alarming signals of increased frequency or severity of COVID-19 in patients with rheumatologic diseases, although extrapolation of the results to other populations with different infection control strategies should be made with caution.