Antiphospholipid antibodies among hospitalized patients predict mortality and readmission: A real-world 10-years...

Antiphospholipid antibodies (aPL) are markers of increased morbidity and mortality in patients with antiphospholipid syndrome. However, the prognostic significance of aPL positivity in hospitalized patients without antiphospholipid syndrome remains unclear. This real-world study evaluated the independent clinical implications of aPL positivity in a large hospitalized population.

We conducted a retrospective cohort study of 4,801 hospitalized patients who underwent aPL testing at Sheba Medical Center between 2006 and 2018, after excluding patients with antiphospholipid syndrome or systemic lupus erythematosus. The patients were classified as either aPL-positive or aPL-negative. Primary outcomes were all-cause mortality over 10 years and all-cause readmission within one year of discharge. Associations between individual aPL isotypes, titers, and outcomes were also examined.

During follow-up, aPL-positive patients experienced significantly higher long-term mortality (HR = 1.40) and one-year readmission rates (HR = 1.25) compared with aPL-negative patients. These findings remained robust after multivariable adjustment. Mortality was specifically associated with the presence of lupus anticoagulant (HR = 1.82), anti-cardiolipin IgG antibodies (HR = 1.66), and low-titer IgM antibodies against β2-glycoprotein I (HR = 1.36) and cardiolipin (HR = 1.49).

In this large real-world cohort, antiphospholipid antibody positivity during hospitalization was independently associated with increased mortality and readmission. Lupus anticoagulant and anticardiolipin IgG showed the strongest associations with adverse outcomes, while low-titer IgM antiphospholipid antibodies were also associated with increased mortality. These findings indicate that antiphospholipid antibody positivity identifies a high-risk subgroup among hospitalized patients.