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Hepatitis C increased risk for immune thrombocytopenic purpura

Patients with hepatitis C may be at an increased risk for developing immune thrombocytopenic purpura, according to a study conducted among U.S. veterans. The treatment of hepatitis C with interferon alfa may also increase the risk of ITP as well as autoimmune hemolytic anemia, according to the study’s findings.

Several small single-institution studies have previously linked hepatitis C to the development of autoimmune cytopenias. In this study, researchers examined a large cohort of 120,691 U.S. veterans infected with hepatitis C and compared them with 454,905 matched uninfected veterans. Mean follow-up was 2.5 years.

At the end of follow-up, there were 296 cases of ITP and 90 cases of autoimmune hemolytic anemia. The overall incidence rate of ITP was higher in veterans infected with hepatitis C compared with uninfected veterans (30.2 vs. 18.5 per 100,000 person years). Incidence of autoimmune hemolytic anemia was also higher among infected veterans compared with uninfected veterans (11.4 vs. 5.0 per 100,000 person years).

Infection with hepatitis C was associated with an increased risk for both ITP (HR=1.8; 95% CI, 1.4-2.3) and autoimmune hemolytic anemia (HR=2.8; 95% CI 1.8-2.4).

Researchers found that the development of autoimmune hemolytic anemia was associated with hepatitis C treatment and not the disease itself. Patients treated for hepatitis C had a HR of 11.6 for developing autoimmune hemolytic anemia (95% CI, 7.0-19.3).

However, both hepatitis C (HR=1.7; 95% CI, 1.3-2.2) and treatment for hepatitis C with interferon alfa (HR=2.4; 95% CI 1.5-3.7) were independently associated with an increased risk for ITP. by Leah Lawrence

Arch Intern Med. 2009;169:357-363