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.

Background: The clinical implications of platelet count changes in patients with bronchiolitis throughout hospitalization have not been extensively investigated. We aimed to investigate the significance of platelet count on admission and platelet count changes during hospitalization in pediatric patients with bronchiolitis. Methods: Clinical data from 559 consecutive patients hospitalized for bronchiolitis were collected and compared after grouping according to the platelet count on admission and the delta platelet count during hospitalization (the platelet count on discharge minus the platelet count on admission; Group A, delta platelet count ≤ -50 × 109/L; Group B, -50 × 109/L < delta platelet count ≤ 50 × 109/L; Group C, delta platelet count > 50 × 109/L). Results: Thrombocytosis was found in 122 (21.8%) patients, while 437 (78.2%) patients had a normal platelet count on admission. There was no difference in disease severity between these two groups. Groups A, B, and C comprised 79 (14.1%), 179 (32.0%), and 301 (53.9%) patients, respectively. The patients from Group A had a higher platelet count on admission, a lower platelet count on discharge, and a longer hospitalization duration. These patients had a lower concentration of C-reactive protein, longer periods of oxygen therapy and stay in the pediatric intensive care unit (PICU), and a greater frequency of mechanical ventilation than the patients from Group B or Group C. Notably, among all the patients, the delta platelet count [63 (-3–142) × 109/L] negatively correlated with the numbers of days of oxygen therapy [4.0 (3.0–6.0), day] (r = -0.186, P = 0.027) and stay in the PICU [5.0 (3.0–6.0), day] (r = -0.391, P = 0.001). Conclusions: Repeated assessment of platelet count during hospitalization in pediatric patients with bronchiolitis may provide useful information for disease management.

Background: To explore the profile and clinical significance of proinflammatory cytokines in serum and bronchoalveolar lavage fluid (BALF) of children with Mycoplasma pneumoniae pneumonia(MPP) and to elucidate the etiology and pathogenesis of severe MPP (SMPP). Methods: A cohort of 108 children with MPP was divided into SMPP (n=56) and non-severe MPP (NSMPP) (n=52). A total of 40 cases of hospitalized children, who underwent elective surgery, were selected as control group. The levels of proinflammatory cytokines in the serum and BALF were measured by ELISA(Enzyme-linked immunosorbent assay). Results: Compared to the control group, the MPP children showed that the levels of peripheral blood (PB) TNF-a, IFN-g, GM-CSF, IL-17, IL-18, IL-36a, sB7-H1, and sB7-H3 were much higher at the acute phase (P<0.05). Also, they were significantly higher in the SMPP group than that in the NSMPP group (P<0.05). Furthermore, in the SMPP group, the levels of TNF-a, IFN-g, GM-CSF, IL-1b, IL-2, IL-8, IL-36, MPO, MMP-9, NE, sB7-H3 in BALF were significantly higher at acute phase as compared to the control group (P<0.05). sB7-H3 was positively correlated with major proinflammatory cytokines in both PB and BALF specimens. The level of sB7-H3 in PB was >8000 pg/mL was an independent risk factor for SMPP. Conclusions: Excessive inflammation plays a critical role in the occurrence and development of MPP, especially SMPP, and sB7-H3 is an independent risk factor of SMPP.