Risk factors and outcomes for repeat COVID-19 infection among patients with systemic autoimmune rheumatic diseases: A case-control study.

Objective: To investigate risk factors and outcomes of repeat COVID-19 infections among patients with systemic autoimmune rheumatic diseases (SARDs).

Methods: We performed a case-control study investigating repeat COVID-19 infection within the Mass General Brigham Health Care System. We systematically identified all SARD patients with confirmed COVID-19 (15/Mar/2020 to 17/Oct/2022). Cases had confirmed repeat COVID-19 infections >60 days apart (index date: repeat COVID-19 date). Controls were matched to cases (up to 3:1) by calendar date of first infection and duration between first COVID-19 infection and index dates. We collected demographics, lifestyle, comorbidities, SARD features, and COVID-19 characteristics at initial infection and index date by medical record review. We used conditional logistic regression to identify associations with repeat COVID-19 infection, adjusting for potential confounders. We described the severity of repeat COVID-19 infection among cases.

Results: Among 2203 SARD patients with COVID-19, we identified 76 cases with repeat COVID-19 infection (80.3 % female) and matched to 207 matched controls (77.8 % female) with no repeat infection. At first infection, cases were younger (mean 49.5 vs. 60.3 years, p < 0.0001), less likely to have hypertension (32.9 % vs. 45.9 %, p = 0.050), and less likely to have been hospitalized for COVID-19 (13.2 % vs. 24.6 %, p = 0.037) than controls. At index date, cases were more likely than controls to be rituximab users (18.4 % vs. 6.3 %, p = 0.0021). In the multivariable model, younger age (OR 0.67 per 10 years, 95 %CI 0.54-0.82), rituximab use vs. non-use (OR 3.38, 95 %CI 1.26-9.08), and methotrexate use vs. non-use (OR 2.24, 95 %CI 1.08-4.61) were each associated with repeat COVID-19 infection. Among those with repeat COVID-19 infection, 5/76 (6.6 %) were hospitalized and there were no deaths.

Conclusion: Younger age, rituximab, and methotrexate were each associated with repeat COVID-19 infection risk among patients with SARDs. Reassuringly, there were no deaths, and the hospitalization rate was low among those with repeat COVID-19 infection.