Background/Purpose: Little is known about inpatient epidemiology, morbidity, mortality and resource utilization of patients with antiphospholipid syndrome (APS). The purpose of this study is to describe those characteristics using a nationwide inpatient database.

Methods: Patients with APS were identified from the Nationwide Inpatient Sample (NIS), the largest inpatient database in the United States (US) that prospectively collects data of hospitalizations of over 4,000 non-federal acute care hospitals, using ICD-9 CM codes. Propensity score matching was used to create cohort of patients without APS to serve as comparator. They were matched to patients with APS using age, sex and Charlson Comorbidity Index as covariates. Data on demographics, reasons for hospitalization, length of stay, mortality, morbidity and expenditures were extracted. All analyzed data was extracted from the databases of the year 2019.

Results: The inpatient prevalence of APS was 85.4 cases per 100,000 admissions. The cohort was predominantly female (73.2%) with the mean age of 51.7 years. Comparing with propensity score-matched comparators without APS, hospitalizations among patients with APS were significantly associated with longer length of stay (1.8 more days; 95% confidence interval (CI), 1.1 – 2.5) and risk for development of acute kidney injury with odds ratio (OR) of 1.29 (95% CI, 1.10 – 1.50). Other inpatient outcomes, including inpatient mortality, shock, multiorgan failure and admission to intensive care unit were not significantly different between patients with and without APS. Hospitalizations of patients with APS were associated with higher cost as demonstrated by an additional mean of $5,300 (95% CI, $4499 – $6101) for total hospital cost and an additional mean of $20,420 (95% CI, $16535 – $24305) for total hospitalization charges when compared to patients without APS.

Conclusion: Inpatient prevalence of APS was higher than what would be expected from prevalence in general population. Hospitalizations of patients with APS were associated with longer length of stay and higher healthcare expenditures.

ACR Meeting Abstracts - https://acrabstracts.org/abstract/inpatient-epidemiology-expenditures-and-resource-utilization-of-antiphospholipid-syndrome-national-inpatient-sample-2019/