The SLICC/ACR damage index, assessed using a community-based electronic healthcare record, predicts mortality in SLE patients: results from the United Kingdom Clinical Practice Research Datalink.

Abstract

Objectives: 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 thus to design an instrument for measurement of 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 an 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 two 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 [odds ratio 6.33 (95% CI 5.34, 7.49)]. Development of damage (eSDI >0 or as a 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.