The value of mean platelet volume in the determination of community acquired pneumonia in children

BACKGROUND Mean platelet volume (MPV) is a reflection of platelet size, which has been shown to correlate with platelet function and activation. The aim of this study was to evaluate whether MPV could be used for the diagnostic tool of community-acquired pneumonia (CAP) and for making the decision for hospitalization. METHODS The computerized records of children aged 1 to 18 years who were diagnosed with CAP based on WHO criteria were evaluated. A standard protocol was followed, and patients with severe CAP were hospitalized. CAP patients were divided into two groups based on disease severity. The control group consisted of age and gender matched healthy children during the study period. Values for hemoglobin, white blood cell count (WBC), platelet count, MPV and C-reactive protein (CRP) obtained on first presentation were recorded for each patient. RESULTS A total of 196 patients were diagnosed with CAP during the study period, 108 (55.1%) of which had severe disease, which required hospitalization (Group 1a), while the remaining 88 (44.9%) were followed-up as outpatients (Group 1b). The control group consisted of 100 healthy children (Group 2). Patients with CAP had lower MPV values than their healthy counterparts (7.1 ± 0.68 vs. 8.31 ± 1.2 fL; p<0.001). MPV value was significantly higher in hospitalized CAP patients compared to outpatients (7.32 ± 0.71 vs. 6.83 ± 0.5 fL; p=0.012). ROC curve analysis suggested that MPV level cut-off point for making a diagnosis of CAP was 8.1 fL, with a sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 91%, 51%, 80.8% and 70.5%, respectively. CONCLUSIONS Our findings suggest that MPV may be a useful predictor for diagnosed CAP but low specificity and NPV rates may lead to the false-negative diagnosis.