Effect of SARS-CoV2 infection on disease flares in patients with systemic lupus erythematosus: a case-control study

To study the effect of SARS-CoV2 infection on flares of systemic lupus erythematosus (SLE).

Patients who fulfilled the ACR/SLICC criteria for SLE and had documented COVID-19 between February and November 2022 were identified retrospectively from our hospital COVID-19 registry. SLE controls who did not have SARS-CoV2 infection were randomly matched for age, sex and the time of infection in a 2:1 ratio with those infected. The primary outcome of interest was clinical flare of SLE within 90 days of COVID-19. The rate of SLE flares (mild/moderate or severe) was compared between SARS-CoV2-infected SLE patients and controls.

Ninety-one SLE patients with COVID-19 (age 48.6 (14.0) years; 95.6% women) and 182 SLE controls (age 48.7 (13.8) years; 95.6% women) were studied. Eleven of 91 (12.1%) SARS-CoV2-infected patients had serious manifestations. One (1.1%) patient died and 7 (7.7%) developed severe complications. Within 90 days of SARS-CoV2 infection, 14 (15.4%) patients developed mild/moderate clinical SLE flares and two (2.2%) patients had severe SLE flares. The incidence of SLE flares in SARS-CoV2-infected patients was significantly higher than in those without the infection (17.6% vs 5.5%; odds ratio 3.67 [95% CI: 1.59, 8.46]; P = 0.001). The changes in anti-dsDNA and complement levels, however, were not significantly different between the two groups. Among SARS-CoV2-infected SLE patients, those with clinical SLE flares had significantly lower C3 values (P = 0.004) before the infection than those without.

Clinical flares within 90 days were significantly more common in SLE patients infected with SARS-CoV2 than matched non-infected SLE controls.