Infection factors of secondary infection in patients with primary immune thrombocytopenia

Abstract

Objective Explore secondary infection risk factors of patients with primary immune thrombocytopenia (ITP) within 1 year after diagnosed. Methods From July 2007 to July 2015, a total 47 ITP patients with secondary infection within 1 year after diagnosis were included in the study as infection group (n=14), who were chosen from 522 ITP patients in the 100th Hospital of the Chinese People′s Liberation Army. According to the proportion of 1∶1.4, 67 uninfected ITP patients were chosen as non-infection group (n=67) randomly. The clinical features, laboratory findings, treatment methods and curative effects were statistically compared by univariate analysis between two groups, and the clinical indicators which had been resulted by univariate analysis and clinical experiences were included in the multivariate unconditional Logistic regression analysis. The receiver operating characteristic curve(ROC) was taken to analyse the influencing factors on the predictive value of ITP patients with secondary infection. Results ①There were statistically significant differences between two groups in age and complications (t=4.559, χ2=11.400; P<0.001). ②The absolute lymphocyte count (ALC) in infection group was (1.5±0.2)×109/L, which lower than that of non-infection group (1.6±0.1)×109/L, and the levels of C-reactive protein (CRP) and lactate dehydrogenase (LDH) in infection group were (19.6±5.1) mg/L and (286.6±15.7) U/L, respectively , which were higher than those of non-infection group, and the differences were significant (t=-0.369, 2.792, 2.828; P<0.05). ③The number of patients who accepted treatment of splenectomy and rituximab were 7 cases and 4 cases, respectively , which higher than those of non-infection group(1 cases and 0) , and the difference was statistically significant (χ2=7.603, 5.909; P<0.05). ④There was significant difference in clinical effect between two groups (χ2=8.257, P=0.016). ⑤Multivariate Logistic regression analysis showed that age (OR=1.074, 95%CI: 1.025-1.125), LDH (OR=1.021, 95%CI: 1.006-1.035), splenectomy (OR=12.423, 95%CI: 1.252-123.245) were independent risk factors of ITP patients with secondary infection, and ALC (OR=0.051, 95%CI: 0.011-0.243) was independent protective factor of ITP patients with secondary infection. ⑥The best age limit which predicted ITP patients with secondary infection was 47.5 years old, the area under curve(AUC) was 0.718, the sensitivity and specificity were respectively 76.6% and 61.2%; the best ALC value is 0.957×109/L, the AUC was 0.631, the specificity was 85.1%, and the sensitivity was 46.8%; the best LDH value was 183.5 U/L, the AUC was 0.673, the specificity was 35.1%, sensitivity was 92.9%. Conclusions Age, LDH level and splenectomy were independent risk factors of ITP patients with secondary infection with 1 year after diagnosis, ALC was its independent protective factor. All the factors above could better predict the risk of infection. Key words: Thrombocytopenia; Infection; Age of onset; Lymphocyte count; Lactate dehydrogenases