Comorbidities in patients with persistent or chronic immune thrombocytopenia.

There is a paucity of epidemiological data on the risk of comorbidities in adults with persistent or chronic immune thrombocytopenia (ITP). In this study, we compared the rates of cataracts, diabetes, renal failure, vascular events, lymphoma, and leukemia among patients with and without persistent or chronic ITP. Using administrative data, adult patients with medical claims for ITP from January, 2000 through September, 2006 were identified. An age- and gender-matched comparison cohort without evidence of ITP was randomly selected. The incidence rate ratio (IRR) of each comorbidity among ITP patients relative to the comparison group was estimated using Poisson regression, adjusting for baseline covariates. A total of 3,131 patients with persistent or chronic ITP were identified, and 9,392 were selected for the comparison cohort. The adjusted IRRs were as follows: diabetes 1.73 (95% CI 1.36-2.20), renal failure 2.05 (95% CI 1.67-2.51), any vascular event 1.70 (95% CI 1.41-2.05), lymphoma 5.91 (95% CI 2.61-13.37), leukemia 19.83 (95% CI 5.84-67.34), and mortality 4.21 (95% CI 3.06-5.79). There was no increased risk for cataract or myocardial infarction in the ITP cohort. Patients with persistent or chronic ITP are at increased risk for several comorbidities including hematologic malignancies, relative to a matched comparison cohort.