Objective This study aimed to investigate whether complete blood count parameters have predictive properties in diagnosing coronavirus disease 2019 (COVID-19) in regard to positive polymerase chain reaction (PCR) test in children with a prediagnosis of COVID-19, and whether these parameters are related to the severity of clinical findings in children with COVID-19.

Methods This retrospective cross-sectional study included children who were hospitalized with a possible diagnosis of COVID-19 and had undergone PCR testing in the COVID-19 children's clinic. Probable case definition was made according to the COVID-19 diagnostic and therapeutic guidelines of the Ministry of Health of the Republic of Turkey.

Results A total of 133 patients were included in the study, of which 46 (34.6%) were negative for the PCR test and 87 (65.4%) were positive for the PCR test. white blood cell (WBC), neutrophil, lymphocyte, and platelet levels were significantly lower in the PCR positive group than in the PCR negative group. The platelet to mean platelet volume ratio (PLT/MPV) was significantly lower in the PCR positive group than the PCR negative group, whereas the platelet distribution width (PDW) of the PCR positive patient group was significantly higher than the PCR negative group. For the multivariable model with PDW and neutrophil to lymphocyte ratio/age factors included, F1 score was 0.864, area under the receiver operating characteristics was 0.804, and area under the precision-recall curve was 0.873. The decision tree had a 72.9% cross-validation accuracy value.

Conclusion WBC, neutrophils, lymphocytes, platelets, PLT/MPV, and PDW parameters could be used in conjunction with clinical symptoms and findings to predict the PCR test result.

目的 本研究旨在探讨全血细胞计数参数是否对诊断为 COVID-19 的儿童的聚合酶链反应 (PCR) 检测阳性 2019 年冠状病毒病 (COVID-19) 具有预测性，以及这些参数是否适用与 COVID-19 儿童临床表现的严重程度相关。

方法 这项回顾性横断面研究纳入了可能因 COVID-19 诊断而住院并在 COVID-19 儿童诊所接受 PCR 检测的儿童。可能的病例定义是根据土耳其共和国卫生部的 COVID-19 诊断和治疗指南进行的。

结果 研究共纳入 133 名患者，其中 46 名（34.6%）PCR 检测呈阴性，87 名（65.4%）PCR 检测呈阳性。PCR 阳性组的白细胞 (WBC)、中性粒细胞、淋巴细胞和血小板水平显着低于 PCR 阴性组。PCR阳性组的血小板与平均血小板体积比（PLT/MPV）显着低于PCR阴性组，而PCR阳性患者组的血小板分布宽度（PDW）显着高于PCR阴性组。对于包含PDW和中性粒细胞与淋巴细胞比率/年龄因素的多变量模型，F1评分为0.864，受试者操作特征下面积为0.804，精确召回曲线下面积为0.873。决策树的交叉验证准确率为 72.9%。

结论 WBC、中性粒细胞、淋巴细胞、血小板、PLT/MPV、PDW参数可结合临床症状和发现预测PCR检测结果。