Prevalence of Systemic Lupus Erythematosus in Australia, 2010-2022: A Population-Based Study Using Linked National...

Systemic lupus erythematosus (SLE) is a heterogenous inflammatory condition with widely varying global prevalence estimates. The frequency of SLE in the general population of Australia has been reported to be notably lower than contemporary estimates in countries such as the United States or United Kingdom, at 19 to 39 per 100,000 as opposed to 65 to 97 per 100,000. This study aimed to develop a national SLE cohort using linked administrative data sets and to estimate prevalence using this approach.

We developed an algorithm to identify SLE cases using the National Health Data Hub, a linked national administrative data asset, which includes data on medications dispensed and medical services subsidized under Australia's universal subsidized coverage schemes, hospital admissions, and deaths. These classification criteria were developed with an expert panel of rheumatologists. Individuals were classified as "certain," "uncertain," or "no SLE." Cohort characteristics were described, and period prevalence (2010-2022) was calculated.

A cohort of 26,788 individuals with SLE were identified, which comprised 16,294 certain cases and 10,494 uncertain cases. The period prevalence of SLE in Australia from 2010 to 2022 was 77 to 127 per 100,000 (certain cases or overall cases). Among the certain cases, just over half had received care for SLE only in an outpatient setting.

This is the first Australian SLE study using comprehensive linked administrative health data, and it identified higher prevalence than previously reported, more closely aligning with international estimates. This algorithm may serve as a foundation for future Australian and international studies seeking to identify SLE in administrative health data sets.