The SLICC/ACR Damage Index, assessed using a community-based electronic healthcare record, predicts mortality in systemic lupus erythematosus patients: results from the UK Clinical Practice Research Datalink

Objectives Systemic lupus erythematosus (SLE), the exemplar autoimmune multisystem disease, is still burdened by excess morbidity and mortality. Damage is a key mediator of this. Studies of damage in outside of hospital cohorts are lacking, limiting understanding of real-world patient outcomes. The objectives were therefore to design an instrument for measurement of Systemic Lupus Erythematosus (SLE) organ damage (eSDI) usable within a UK electronic primary care healthcare database (Clinical Practice Research Datalink [CPRD]) and describe the accrual of damage and mortality associations in a SLE cohort. Methods A cohort of SLE individuals, including incident and prevalent cases, was identified in the CPRD. Organ damage item definitions were made usable for the electronic registry setting. Prevalence of damage in the overall cohort was described using descriptive statistics. Associations with mortality and damage (expressed in 2 ways, SDI > 0 ever, or modelled as a continuous cumulative variable) were examined using multivariable logistic regression, Kaplan-Meier analysis and extended Cox Proportional Hazards Analysis in the incident SLE population. Results We identified 8363 SLE patients in total, of whom the eSDI measured damage in 3537 (42·3%). The most common items were osteoporosis (10·39%), malignancy (8·4%) and cataract (7·4%). Damage across all organ systems was associated with an increased odds of death (e.g. malignancy [OR 6·33, 95% CI 5·34-7·49]). Development of damage (eSDI >0 or as numerical damage score) was significantly associated with an increased hazard of mortality. Conclusion The use of an adapted eSDI for community electronic health records is feasible and enables widening of the study of damage and its morbidity and mortality consequences to primary care populations. This is more likely to reflect the real-world accumulation and outcomes of damage over time in SLE.