Background/Purpose: Autoimmune Hemolytic Anemia (AIHA) is one of the manifestations of Systemic lupus erythematosus (SLE), an autoimmune connective tissue disease. AIHA may be present in 3% of SLE patients at the time of diagnosis or within the first year of the disease. Despite the known association between SLE and AIHA, no study has explored the outcomes of AIHA in patients who are admitted for SLE. In this study, we aimed to analyze the mortality rate as the primary outcome, Length of Stay(LOS), Total Hospital Charges(THC), the incidence of Pulmonary Embolism (PE), Myocardial Infarction (MI), Cerebrovascular Accident (CVA), Acute Kidney Injury (AKI), health care utilization as secondary outcomes in SLE patients with and without AIHA.

Methods: Nationwide Inpatient Sample (NIS) from 2016-2019 was queried to determine adult hospitalized patients with a primary diagnosis of SLE using ICD-10 codes. The primary outcome was defined as the effect of AIHA on inpatient mortality in those patients. Secondary outcomes included LOS, THC, health care utilization, AKI, PE, CVA, and MI. We evaluated the baseline characteristics using the t-test and chi-square test. Multivariable logistic regression analysis was performed to assess the association of SLE with AIHA and inpatient mortality adjusted by age, gender, race, Charlson index, insurance, and household income.

Results: A total of 41004 SLE patients were hospitalized, and 2.2% of these patients had AIHA. SLE patients with AIHA were younger (33.1 vs. 38.1 years, p < 0.001), less likely to be African American, and more likely to be Asian (35% vs. 45% and 22% vs. 12%, respectively, p = 0.003) compared to other cohorts. Also, these patients were more likely to have Medicaid and less likely to have Medicare ( 40% vs. 35% and 11% vs. 27%, respectively, p< 0.001) compared to SLE without AIHA. There was no significant difference in sex and median household income between the 2 groups.

SLE with AIHA had a higher odds ratio with increased all-cause mortality compared to SLE without AIHA (OR 4.14, 95% CI 1.98-8.66, p < 0.0001), and the adjusted OR was 4.24 (95% CI 1.03 – 1.52, p = 0.025). Age and Charlson index were also associated with increased inpatient mortality among hospitalized patients with SLE after being adjusted for other variables. In addition, SLE with AIHA was associated with an increased LOS, mean 11.72 vs. 6.44 days (adjusted difference 5 days p=0.002), and higher THC (mean $140604 vs. $69140 p< 0.0001).

In patients who were admitted to the hospital with SLE, the presence of AIHA was significantly associated with an increased incidence of AKI (adjusted OR 1.49, 95% CI 1.06-2.08, p=0.019), MI (adjusted OR 3.76, 95% CI 1.1 – 12.7, p = 0.034) and ICU admissions (adjusted OR 2.88, 95% CI 1.51 – 5.51, p = 0.001) compared to SLE without AIHA. No significant difference was found in the incidence of PE, CVA, and health care utilizations like nursing homes and home health care.

Conclusion: Hospitalized SLE patients with AIHA have higher odds of inpatient mortality, AKI, MI, LOS, and THC than SLE patients without AIHA. AIHA should be identified and considered as a higher risk of mortality and worse outcomes in SLE patients. Further studies should be done to explore if early detection and treatment of AIHA could improve outcomes in SLE.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/outcomes-of-autoimmune-hemolytic-anemia-in-patients-with-systemic-lupus-erythematosus-a-nationwide-inpatient-sample-study/