Purpose Because of the involvement of type 1 interferon (IFN-1) in the pathophysiology of both systemic lupus erythematosus (SLE) and COVID-19 immune response, a risk of post COVID-19 SLE flare could be hypothesized. Our objectives were to assess this risk and to look for factors associated with a post-COVID-19 SLE flare.

Methods We conducted a retrospective cohort study using the Assistance Publique - Hôpitaux de Paris (AP-HP) Clinical Data Warehouse which collects all the medical data produced in the 39 AP-HP facilities in Paris area. We included every adult patient with a history of SLE (defined by a ‘M32’ ICD-10 diagnosis code) and an hospital stay with a first episode of COVID-19 diagnosis (defined by a ‘U07.1’ ICD-10 code) between March 2020 and February 2022. All the medical records were individually reviewed to retrieve demographics, SLE characteristics, COVID-19-episode characteristics, and vaccination status. We look for clinically defined SLE flares during the follow-up period. Features associated with post COVID-19 SLE flares were analysed by using univariable and multivariable logistic regression procedures.

Results Among the 4,533 SLE patients followed in AP-HP, 128 (2.8%) had an hospital stay with a COVID-19 diagnosis during the period of interest. After reviewing all the individual records, we excluded 38 patients who did not meet the inclusion criteria. Accordingly, there were 90 patients included in the analysis; 84 (93.3%) were female with a median [IQR] age of 54.6 [40.8–68.3] years. The median time between SLE diagnosis and the COVID-19 episode was 13.5 [5.6–22.8] years. Seventy-three (81.1%) patients did not receive any dose of anti-Sars-Cov2 vaccine before the COVID-19 episode and 9 (10%) died directly from COVID-19. We observed 14 (15.5%) post-COVID-19 SLE flares, 6 (42.9%) of them occurred in the same hospital stay. The median time between the beginning of the COVID-19 episode and the SLE flare was 60 [20.5–117.5] days. Six (42.9%) of these flares involved the kidneys with 3 (21.4%) class III or IV glomerulonephritis. We did not observe any significant difference in the characteristics of patient who experienced a flare compared to the others. Interestingly, there were no difference in the proportion of patients vaccinated between the two groups: 10/14 (76.9) in the flare group versus 62/74 (83.8%) in the group with no flare (p=0.83).

Conclusions Autoimmune flares seem to be frequent after COVID-19 infection among SLE population. We did not identify any risk factor associated with a risk of post-COVID-19 SLE flare.