BACKGROUND Coronavirus disease 2019 (COVID-19) is a novel infectious disease with lack of established laboratory markers available to evaluate illness severity. In this study, we investigate whether platelet count could differentiate between COVID-19 patients with or without severe disease. Additionally, we evaluate if thrombocytopenia is associated with severe COVID-19. METHODS An electronic search in Medline, Scopus and Web of Science was performed to identify studies reporting data on platelet count in COVID-19 patients. A meta-analysis was performed, with calculation of weighted mean difference (WMD) of platelet number in COVID-19 patients with or without severe disease and odds ratio (OR) of thrombocytopenia for severe form of COVID-19. RESULTS Nine studies with 1779 COVID-19 patients, 399 (22.4%) with severe disease, were included in the meta-analysis. The pooled analysis revealed that platelet count was significantly lower in patients with more severe COVID-19 (WMD -31 × 109/L; 95% CI, from -35 to -29 × 109/L). A subgroup analysis comparing patients by survival, found an even lower platelet count was observed with mortality (WMD, -48 × 109/L; 95% CI, -57 to -39 × 109/L. In the four studies (n = 1427) which reported data on rate of thrombocytopenia, a low platelet count was associated with over fivefold enhanced risk of severe COVID-19 (OR, 5.1; 95% CI, 1.8-14.6). CONCLUSIONS Low platelet count is associated with increased risk of severe disease and mortality in patients with COVID-19, and thus should serve as clinical indicator of worsening illness during hospitalization.

中文翻译：

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血小板减少症与严重的冠状病毒病2019（COVID-19）感染相关：一项荟萃分析。

背景冠状病毒疾病2019（COVID-19）是一种新型传染病，缺乏可用于评估疾病严重程度的已建立实验室标记。在这项研究中，我们调查了血小板计数是否可以区分有或没有严重疾病的COVID-19患者。此外，我们评估血小板减少症是否与严重的COVID-19相关。方法在Medline，Scopus和Web of Science中进行了电子搜索，以鉴定报告COVID-19患者血小板计数数据的研究。进行荟萃分析，计算有或没有严重疾病的COVID-19患者的血小板数量加权平均差（WMD）和严重形式COVID-19的血小板减少症的比值比（OR）。结果9项研究对1779名COVID-19患者，399名（22.4％）患有严重疾病的患者进行了研究，纳入荟萃分析。汇总分析显示，重度COVID-19（WMD为-31×109 / L； 95％CI为-35至-29×109 / L）的患者血小板计数显着降低。亚组分析按存活率比较患者，发现血小板计数甚至更低（WMD，-48×109 / L； 95％CI，-57至-39×109 / L。在四项研究中（n = 1427） ）报告了血小板减少症的发生率，血小板计数低与重度COVID-19风险增加5倍以上有关（OR，5.1； 95％CI，1.8-14.6）。 COVID-19患者的疾病和死亡率，因此应作为住院期间病情恶化的临床指标。汇总分析显示，重度COVID-19（WMD为-31×109 / L； 95％CI为-35至-29×109 / L）的患者血小板计数显着降低。亚组分析按存活率比较患者，发现血小板计数甚至更低（WMD，-48×109 / L； 95％CI，-57至-39×109 / L。在四项研究中（n = 1427） ）报告了血小板减少症的发生率，血小板计数低与重度COVID-19风险增加5倍以上有关（OR，5.1； 95％CI，1.8-14.6）。 COVID-19患者的疾病和死亡率，因此应作为住院期间病情恶化的临床指标。汇总分析显示，重度COVID-19（WMD -31×109 / L； 95％CI，从-35至-29×109 / L）的患者的血小板计数显着降低。亚组分析按存活率比较患者，发现血小板计数甚至更低（WMD，-48×109 / L； 95％CI，-57至-39×109 / L。在四项研究中（n = 1427） ）报告了血小板减少症的发生率，血小板计数低与重度COVID-19风险增加5倍以上有关（OR，5.1； 95％CI，1.8-14.6）。 COVID-19患者的疾病和死亡率，因此应作为住院期间病情恶化的临床指标。低血小板计数与严重COVID-19风险增加五倍以上有关（OR，5.1； 95％CI，1.8-14.6）。结论低血小板计数与COVID-19患者严重疾病和死亡的风险增加相关，因此应作为住院期间病情恶化的临床指标。低血小板计数与严重COVID-19风险增加五倍以上有关（OR，5.1； 95％CI，1.8-14.6）。结论低血小板计数与COVID-19患者严重疾病和死亡的风险增加相关，因此应作为住院期间病情恶化的临床指标。