Although immunosuppressive therapy for immune thrombocytopenia (ITP) can lead to infections, the lower platelet counts in these patients from ITP itself may also contribute to infections, according to a study published in Annals of Hematology.

Platelets themselves are beginning to be understood as playing a role in immune response, although mechanisms remain unclear.

In this retrospective study of platelet- and infection-related data from 158 patients with primary ITP from the first month of a clinical trial in China, investigators used Cox regression analyses to evaluate connections between platelet levels and infections.

Over the course of the month, patients without infections (n = 120) typically showed statistically significantly higher mean platelet counts (P <.01 at 1, 2, and 4 weeks) than did patients with infections (n = 38). Infections also reduced the rate of response to treatment and resulted in longer hospital stays (9.8 ± 5.2 days without infection vs 14.0 ± 8.7 days with infection; P <.01).

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The researchers found that for every platelet count increase of 20×109/L, risk of infection in the following week decreased by 52% (HR 0.52; 95% CI 0.35-0.77; P =.001).

Increasing platelet counts through transfusions showed mixed effects, with transfusions leading to slightly increased platelet levels in patients without infection but not in patients with infections. The researchers recommended against prophylactic transfusions.

The researchers cautioned that the retrospective nature of the study limited interpretations beyond an assessment of correlations and recommended further study to establish mechanisms and associations.

Reference

Qu M, Liu Q, Zhao H, et al. Low platelet count as risk factor for infections in patients with primary immune thrombocytopenia: a retrospective evaluation. Ann Hematol. 2018;97(9):1701-1706.