OBJECTIVETo explore incidence, risk factors and prognosis of the first 6 months infectious events in adults with newly diagnosed primary immune thrombocytopenia (ITP), and evaluate the value of initial absolute lymphocyte count (ALC) in predicting infection.

METHODSThe initial clinical records and infectious events during 6 months of 217 adult with newly diagnosed ITP were retrospectively analyzed. Statistical methods were used to analyze risk factors of the 6 months infections in adults ITP, the prediction of ALC in risk of infection, and the association of ALC and prognosis.

RESULTSInfection rate of ITP patients accepting therapy within 6 months after the initial diagnosis was 13.8% (30/217), and infection rate of patients ≥ 60 years of age 25% (14/56). Multivariate unconditioned Logistic analysis showed that gender and ALC were independent risk factors for the 6 months infection of ITP patients (P<0.05, 95% CI 1.150-7.298, OR 2.722 and P<0.001, 95% CI 6.802-80.749, OR 23.436). Cutoff value of ALC was 1.225 × 10⁹/L, sensitivity and specificity of its value were 0.866 and 0.700 respectively. Infection rate of ALC>1.225 × 10⁹/L in adult ITP was lower than of ALC ≤ 1.225 × 10⁹/L (5.3% vs 45.7%, χ² = 49.151, P<0.001). Furthermore, persistent recovery and the 1-year mortality rate after diagnosis had no difference among patients of different ALC (28.0% vs 26.0%, χ² = 0.071, P>0.05, and 98.6% vs 97.8%, χ² = 0.095, P>0.05). There were no significant differences in persistent recovery in patients with and without infection (30.0% vs 27.3%, χ² = 0.096, P>0.05). The 1-year mortality rate after diagnosis was significantly lower in those patients who developed an infection (93.3% vs 99.3%, χ² = 4.607, P<0.05).

CONCLUSIONInitial ALC was an independent risk factor of 6 months infection in adult ITP. It could be a predictive index of infection within 6 months of the initial diagnosis in ITP patients. Infection as an important factor affected the survival of ITP patients.