Background/Purpose: The reported incidence and mortality of connective tissue diseases (CTDs) in England has been inconsistent in the literature. Our objective was to describe current trends in the incidence and mortality of systemic lupus erythematous (SLE), Sjogren’s syndrome (SjS), systemic sclerosis (SSc), idiopathic inflammatory myopathies (IIM) and mixed connective tissue disease (MCTD).

Methods: We conducted a retrospective population-level study using primary care records in England via the Clinical Practice Research Datalink (CPRD). We included individuals ≥18 years old with new CTD diagnoses between 2012 and 2023. Our outcomes were incidence and all-cause mortality, which included age-standardized mortality rates (ASMRs), standardized mortality ratios and risk of death over time using flexible parametric models.

Results: There were a total of 22,829 incident CTD diagnoses (81.1% female, median age 57). The age and sex-standardised incidence of SLE and SSc fell over the study period 2012 to 2023 (SLE: 4.32 to 3.29 per 100,000 person years (py) and SSc: 2.33 to 1.86 per 100,000 py), whereas SjS and MCTD incidence remained relatively stable (Figure 1). In contrast, IIM diagnoses rose from 3.23 to 4.31 per 100,000 py. ASMRs across the study period were highest for IIM (27.83 per 1,000 py), followed by SSc (24.43), SLE (16.74), MCTD (16.27) and lowest for SjS (9.70) (Table 1). Compared to the general population, mortality was higher in incident SSc, IIM, MCTD and SLE groups (SMRs of 1.74, 1.56, 1.50, and 1.30 respectively). Among all CTDs, the risk of death from time of diagnosis was highest in those diagnosed with IIM or SSc (Figure 2).

Conclusion: Our findings revealed a falling incidence of SLE, a simultaneous rise in IIM incidence and overall high all-cause mortality within IIM and SSc cohorts. Our findings acknowledge the changing landscape of CTDs in England and will aid healthcare resource planning for this vulnerable population.

Figure 1. Age and sex standardized incidence rates (ASIRs) by year, 2012-2023, with 95% confidence intervals (95% CI).

Table 1. Number and characteristics of deaths associated within each incident CTD cohort. Crude and age and sex-standardised mortality rates (AMSRs) are given with 95% confidence intervals (95% CI). Individuals with more than one CTD diagnosis contributed to each relevant group. Counts less than eight were redacted (*).

Figure 2. Risk of death in relation to time from each CTD diagnosis with 95% confidence intervals (shaded area).

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-incidence-and-mortality-of-connective-tissue-diseases-in-england-a-population-level-cohort-study-from-2012-to-2023/