Fig. 1

Study design and data retrieval. A This flow-chart depicts the overall study design including the recruitment of patients for the cross-sectional study and the retrieval of retrospective longitudinal data from the Lund Lupus Cohort database and biobank. B The timeline illustrates the data retrieval for the study. Data retrieval A: In the cross-sectional study patients were assessed extensively by a rheumatologist, neurologist, underwent cognitive testing by a neuropsychologist, MRI, and blood samples. This data was used to assess the associations between the lupus phenotypes and MRI changes & cognitive dysfunction. Data retrieval B: Retrospectively, we chose 199 visits with concomitant blood samples with high and low disease activity, including one visit as early as possible. This data was used for investigating the SLEDAI-2 K and IFN-α associations with repeatedly measured plasma NfL, and to collect samples to determine the IFN-α lupus phenotypes. Data retrieval C: All 576 prior visits with SLEDAI-2 K registered in the database were retrieved. This data was used to determine the SLEDAI-2 K lupus phenotypes