Thrombocytosis and thrombocytopenia are markers of poor outcome in pediatric patients with community-acquired pneumonia

Abstract

Background: This study aimed to investigate the prevalence of thrombocytopenia and thrombocytosis in hospitalized pediatric patients with community-acquired pneumonia (CAP), and determine whether thrombocytopenia and thrombocytosis are associated with patient outcome. Methods: A total of 9,372 consecutive patients, who were 1-168 months old, diagnosed with CAP and admitted in the Children’s Hospital of Soochow University, were enrolled in the present retrospective observational study. Their clinical and laboratory data were collected. According to the platelet count on admission, these patients were divided into three groups: thrombocytopenia, normal platelet count, and thrombocytosis groups. The clinical characteristics and etiologic pathogens were compared among these groups. The multivariate logistic regression model was applied to identify risk factors for severe CAP, length of hospitalization ≥10 days and respiratory complications. The correlations between platelet count and clinical features were determined by Spearman’s correlation. Results: Thrombocytosis and thrombocytopenia were found in 3,376 (36.0%) and 43 (0.5%) patients, respectively. Normal platelet count was observed in 5,953 (63.5%) patients. Thrombocytopenia was an independent risk factor of severe CAP (OR, 6.206; 95% CI, 2.209-17.436; P=0.001), while thrombocytosis was associated with length of hospitalization of ≥10 days (OR, 1.315; 95% CI, 1.177-1.470; P<0.001). In addition, thrombocytosis was associated with respiratory complications (OR, 1.658; 95% CI, 1.171-2.346; P=0.004). Platelet count (median 350.0 [IQR 270.2-447.0] × 109/L) was positively correlated with length of hospitalization (median 7.0 [IQR 6.0-9.0] days) (r = 0.101, P<0.001), but negatively correlated with age (median 12.0 [IQR 3.0-36.0] months) (r = -0.401, P<0.001) and C-reactive protein (median 2.0 [IQR 0.3-10.7] mg/dl) (r = -0.191, P<0.001). Conclusion: Thrombocytosis is highly prevalent, while thrombocytopenia has low prevalence in pediatric CAP patients. Both thrombocytosis and thrombocytopenia are associated with clinical outcomes in pediatric CAP patients.