Background/Purpose: Diffuse alveolar hemorrhage (DAH) is a rare but severe complication in Systemic Lupus Erythematosus (SLE), occurring in up to one-third of cases at disease onset. In ANCA-associated vasculitis (AAV), the prevalence of DAH is around 25%, with high morbidity and mortality. DAH in both SLE and AAV requires prompt investigation, presenting challenges in initiating life-saving treatments. The objective of this study is to compare the in-hospital mortality in patients with DAH secondary to AAV versus DAH secondary to SLE, aiming to inform management strategies and improve clinical decision-making.

Methods: We used the National Inpatient Sample database from Jan 2020 to Dec 2022 to compare baseline characteristics and outcomes of patients with DAH due to AAV versus SLE. Both groups were analyzed for demographic factors, comorbidities, hospital-related variables, and clinical outcomes. Key outcomes included length of stay (LOS), total charges, and in-hospital mortality, with logistic regression used to assess factors associated with mortality.

Results: A total of 1,470 patients with AAV + DAH and 915 patients with SLE + DAH were identified. In the AAV + DAH group, 54.2% were female, compared to 50% in the SLE + DAH group. The mean age for AAV + DAH patients was significantly higher at 55.34 years, compared to 43.25 years in the SLE + DAH group. Racial distribution showed 63.4% of AAV + DAH patients were White, compared to 62.5% in the SLE + DAH group. AAV + DAH patients had a higher proportion of severe comorbidities (38.8%) compared to SLE + DAH (37.5%). Hospital region distribution showed SLE + DAH patients were more likely to be admitted to hospitals in the South (50%) compared to AAV + DAH (27.3%). More SLE + DAH patients were admitted to large hospitals (87.5%) compared to AAV + DAH (60.1%) (Fig 1). The mean LOS was 16.30 days for AAV + DAH and 15.87 days for SLE + DAH, with total charges for AAV + DAH higher at $273,083 compared to $233,180 for SLE + DAH. The mortality rate for AAV + DAH was 16.4%, compared to 12.5% for SLE + DAH (p = 0.7671). Logistic regression showed no significant difference in mortality between the two groups. (OR 0.73, p = 0.7680).

Conclusion: This study highlights the similarities and differences in the clinical characteristics, comorbidities, and healthcare burden of DAH secondary to AAV versus SLE. While both groups share significant morbidity and mortality, AAV + DAH patients were older, had more severe comorbidities, and incurred higher healthcare costs compared to SLE + DAH patients. Despite these differences, there was no significant difference in in-hospital mortality between the two groups, suggesting that the severity of DAH may not differ substantially based on the underlying disease. The findings underscore the need for further research to better understand the impact of DAH in these distinct patient populations.

Figure 1: Baseline comparison of Diffuse Alveolar Hemorrhage (DAH) due to Systemic Lupus Erythematosus (SLE) versus ANCA-associated vasculitis (AAV).

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/diffuse-alveolar-hemorrhage-in-anca-associated-vasculitis-aav-and-systemic-lupus-erythematosus-sle-a-comparative-analysis/