Outcome and Identification of Early Risk Factors in a Population-Based Systemic Lupus Erythematosus Cohort Set in Norway

• Main Author: Moe, Sigrid Elise Reppe
• Format: Dissertation
• Language: English

Systemic Lupus Erythematosus (SLE) is a chronic autoimmune disease that can affect any organ and carries a substantial burden, potentially being life threatening. Despite these serious implications, our understanding of SLE prognosis at population level is limited. The aim of this thesis was to establish a medical record confirmed population based SLE cohort in Southeast Norway to provide robust data on SLE outcomes. Our methodology also allowed for the estimation of the accuracy of using solely International classification of diseases and related health problems 10th edition (ICD-10) code-based case definitions for SLE from health administrative databases, an approach increasingly used in SLE research. Given the heterogeneous nature of SLE and its ability to mimic other conditions, this thesis suggest that relying solely on ICD-codes from administrative databases to identify SLE is suboptimal. ICD-code-based case definitions consistently overestimated SLE incidence, expect in the very young, and shifted the age-specific incidence curve towards older ages. The thesis highlights the high risk of thromboembolic events around the time of SLE diagnosis. A novel finding was that this peak in thromboembolic events is largely attributable to the onset of Antiphospholipid Syndrome, a thrombo-inflammatory autoimmune disease that co-occurred in 11% of the SLE patients. Despite good short-term survival rates, SLE patients have over a twofold risk of death compared to their counterparts. This underscores the need for continued focus on long-term morbidity prevention in SLE. The high mortality gap in patients diagnosed before the age of 16, known as juvenile SLE, is particularly concerning and warrants attention. In summary, this thesis contributes to a better understanding of SLE prognosis, with potential implications for disease management. Additionally, it provides an important contribution to the ongoing discussion on the use of health administrative data in SLE research