The association between mean platelet volume and poor outcome in patients with COVID-19: Systematic review, meta-analysis, and meta-regression.

Introduction: This study aims to assess the association between mean platelet volume (MPV) and poor outcome in patients with COVID-19.

Methods: We performed a comprehensive literature search using the PubMed, Embase and Scopus databases with keywords "2019-nCoV" OR "SARS-CoV-2" OR "COVID-19" AND "mean platelet volume" OR "MPV" on 8 July 2021. The primary outcome was composite poor outcome, defined as severe COVID-19 or mortality. The pooled effect estimate was reported as mean differences in terms of MPV between the group with and without outcome.

Results: There were 17 studies which consist of 4549 patients with COVID-19 were included in this study. The incidence of poor outcome was 25% (20%-30%). Mean MPV was found to be higher in the poor outcome group in compare to no poor outcome group (10.3 ± 1.9 fL vs 9.9 ± 1.7 fL). The mean MPV difference between both group was 0.47 fL [95% CI 0.27, 0.67], < 0.001; : 62.91%, < 0.001). In the sub-group analysis, patients with severe COVID-19 had higher MPV (mean difference 0.54 fL [95% CI 0.28, 0.80], < 0.001; : 54.84%, = 0.014). Furthermore, MPV was also higher in the mortality group (mean difference 0.54 fL [95% CI 0.29, 0.80], = 0.020; : 71.11%, = 0.004). Meta-regression analysis showed that the association between MPV and poor outcome was not affected by age ( = 0.789), gender ( = 0.167), platelets ( = 0.056), white blood cells ( = 0.639), and lymphocytes ( = 0.733).

Conclusion: This meta-analysis indicated that increased MPV was associated with severity and mortality in patients with COVID-19. Further research is needed to determine the optimum cut-off point.