Clinical and Laboratory Characteristics, Disease Activity, and Disease Damage: A Saudi National Lupus Cohort Study

Background: Systemic lupus erythematosus (SLE) disease activity and damage assessments are crucial for understanding the disease burden across different lupus populations. This study aims to describe the disease characteristics, treatment, and disease activity and damage in the Saudi national prospective SLE cohort. Methods: Saudi SLE patients over 18 years of age were recruited prospectively from January 2020 to December 2023 from the national prospective cohort of SLE, Saudi Arabia. Data retrieved included patients’ sociodemographic characteristics, medical history, clinical manifestations and laboratory features, comorbidities, and medications at baseline visit, first follow-up at 3 months, and subsequent follow-up visits every 6 months. The SLE disease activity index 2000 (SLEDAI-2K) and Systemic Lupus International Collaboration Clinics/American College of Rheumatology (SLICC/ACR) damage index (SDI) scores were computed at baseline and follow-up visits following a standardized protocol. The generalized linear model was employed to assess organ damage based on the SDI scores. Kaplan–Meier survival analysis was performed to assess major adverse cardiovascular events (MACEs) and mortality. The Cox regression model was used to adjust for lupus disease and cardiovascular risk factors. Results: The mean age at SLE diagnosis of the 488 patients was 30.6 ± 11.9 years. The mean SLEDAI-2K and SDI scores were 8.0 ± 7.2 and 0.61 ± 1.1, respectively. The SLEDAI-2K scores declined initially and increased in follow-up visits. The SDI scores also increased at the follow-up visits. Musculoskeletal organ damage was found in 10.7% of the patients, neuropsychiatric damage in 9.2%, skin damage in 6.1%, renal damage in 5.9%, and cardiovascular damage in 4.4%. The parameters analyzed for predicting organ damage progression did not reach statistical significance, which may be due to the limited statistical power of the study and may not reflect an absence of relationship. Oral prednisolone was administered to 43.1% of the patients and hydroxychloroquine to 89.2%. The Kaplan–Meier 5- and 10-year survival rates were 99% and 98%, respectively. The initial findings using Cox regression analysis indicated that a longer SLE duration is protective of MACEs. However, a sensitivity analysis with a time-dependent approach did not retain significance of the SLE duration on the outcome of early MACEs. There was a trend of obesity and earlier MACE occurrence. Conclusion: Lupus disease activity and disease damage increased from the baseline visit over time. The most prevalent organ damage included musculoskeletal, neuropsychiatric, renal, and cardiovascular systems, consistent with previous studies. Time-invariant analysis showed an association between a longer SLE duration and MACEs, but such findings did not retain significance with a time-dependent approach, which may be due to immortal time bias. Obesity was found to contribute to early MACEs.