Prevalence and correlates of thrombosis in adults with immune thrombocytopenia: An NIS study

Background: Immune thrombocytopenia (ITP) is increasingly recognized as a thrombophilic disorder. However, no further investigation of risk factors has been conducted to date. This study evaluated classic and disease-specific correlates of thrombosis among ITP patients. We hypothesized the disease-specific thrombosis risk profile differed between ITP and non-ITP patients.

Methods: A retrospective analysis of adult discharge data from the National Inpatient Sample between 2009 and 2014 was performed. International Disease Classification codes were used to identify ITP and non-ITP patients with or without thrombosis. Estimates of prevalence were weighted using NIS-provided discharge-level weights to reflect national estimates. Rao-Scott Chi-square test was used to analyze categoric variables; weighted simple linear regression for continuous variables; and a weighted multivariable logistic regression to determine covariates associated with thrombosis.

Results: Thrombotic risk factors are increased in ITP patients, including postoperative state, malignancy, central venous lines, systemic lupus erythematosus, advanced age, obesity, and hypertension. Factors associated with thrombosis identified in multivariable logistic regression included antiphospholipid syndrome, systemic lupus erythematosus, central venous lines, obesity, and hypertension, which were similar to non-ITP patients.

Conclusions: Our results show a higher prevalence of thrombosis in ITP than in non-ITP patients, and despite their lower platelet counts, correlates of thrombosis are similar between ITP and non-ITP patients. The most significant correlates include antiphospholipid syndrome, central venous lines, surgery, hypertension, age, and obesity.