Background/Purpose: Antiphospholipid syndrome (APLS) is characterized by arterial and venous thrombosis, often in the setting of an underlying systemic disease. Few studies have described the varied clinical presentations of this disease. This study aims to characterize healthcare expenditure and inpatient clinical outcomes of APLS using a nationally representative sample.

Methods: Patients with a diagnosis of APLS admitted to U.S. hospitals were identified using the ICD 10 CM classification system. The NIS is an all-payer inpatient database that estimates over 37 million annual U.S. hospitalizations and is maintained by the Healthcare Cost and Utilization Project. The primary outcomes were prevalence of APLS among hospitalized patients. Secondary outcomes included mortality, rate of acute thrombotic complications, and cost of care. Multivariate hierarchical regression analysis was used adjusting for demographics, hospital factors, and comorbid conditions.

Results: Of 79,835 patients identified in this retrospective cohort, 915 were primarily admitted for APLS. Patients were most commonly admitted for cardiovascular (22%), pregnancy-related (10.5%), gastrointestinal (9.3%) and infectious (6.5%) etiologies. Most patients were female (71.1%), white (66.5%) and had a mean age of 51.9 (51.5-52.2, 95% CI) years. Most patients were admitted to urban academic centers (77.7%) and had an average length of stay of 6.5 (6.3-6.6, 95% CI) days. The average hospitalization cost was $18,776 ($18,093-$19,458, 95% CI). 1,720 (2.2%) deaths occurred. The rates of acute arterial and venous thrombotic complications are summarized in Table 1. 21.7% of patients were diagnosed with systemic lupus erythematosus (SLE).

Conclusion: Acute thrombotic events remain a significant cause of morbidity and mortality among patients admitted for APLS. The prevalence of life-threatening thrombotic complications including pulmonary embolism, stroke, myocardial infarction and fetal demise were lower than previously reported [1,2]. These results may reflect overall improvements in disease detection and anticoagulation practices in the community setting and merit further investigation.

1. Cervera R. et al “Antiphospholipid Syndrome: Clinical and Immunologic Manifestations and Patterns of Disease Expression in a Cohort of 1,000 Patients” Arthritis Rheum. 2002 Apr;46(4);1019-27
2. Andreoli L. et al. “Estimated Frequency of Antiphospholipid Antibodies in Patients With Pregnancy Morbidity, Stroke, Myocardial Infarction, and Deep Vein Thrombosis: A Critical Review of the Literature.” Arthritis Care Res. 2013 Nov; 65(11):1869-73

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/epidemiology-of-thromboembolic-complications-among-hospitalized-patients-with-antiphospholipid-syndrome-in-the-united-states/