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Role of platelet-to-lymphocyte count ratio (PLR), as a prognostic indicator in COVID-19: A systematic review and
Soumya Sarkar1, Sundara Kannan1, Puneet Khanna1
1Department of Anaesthesia, Pain Medicine & Critical Care, AIIMS, Ansari Nagar, New Delhi, India.
Insights
The platelet-to-lymphocyte count ratio (PLR) may predict COVID-19 severity and mortality. Higher PLR levels indicate increased risk, but more research is needed to confirm its prognostic value.
Area of Science:
- Infectious Diseases
- Hematology
- Critical Care Medicine
Background:
- The COVID-19 pandemic necessitates reliable prognostic predictors for timely intervention.
- The platelet-to-lymphocyte count ratio (PLR) has shown potential in stratifying sepsis patients.
- Investigating PLR's role in COVID-19 patient outcomes is crucial for healthcare management.
Purpose of the Study:
- To systematically review the utility of the platelet-to-lymphocyte count ratio (PLR) as a prognostic predictor in COVID-19 patients.
- To evaluate the association between admission PLR levels and COVID-19 patient mortality and disease severity.
Main Methods:
- A systematic review of electronic databases was conducted until May 15, 2021.
- Included studies assessed the correlation between PLR on admission and COVID-19 outcomes (mortality, severity).
- Data from 32 studies involving 2768-3262 COVID-19 patients were analyzed.
Main Results:
- Higher admission PLR levels were significantly associated with increased mortality in COVID-19 patients (MD = 66.10, p < 0.00001).
- Critically ill COVID-19 patients exhibited higher PLR levels compared to non-severe cases (MD = 86.74, p < 0.00001).
- A higher PLR on admission correlates with increased morbidity and mortality in COVID-19.
Conclusions:
- Elevated platelet-to-lymphocyte count ratio (PLR) on admission is linked to worse outcomes in COVID-19.
- The current evidence supporting PLR as a prognostic marker is of low quality.
- Further research is required to establish definitive cut-off values for PLR in predicting COVID-19 severity and mortality.
Abstract:
Prognostic predictors are of paramount interest for prompt intervention and optimal utilization of the healthcare system in the ongoing context of the COVID-19 pandemic. The platelet-to-lymphocyte count ratio (PLR), has emerged as a potential tool for risk stratification of critically ill patients with sepsis. The current systematic review explores the utility of PLR as a prognostic predictor of COVID-19 patients. We screened the electronic databases until May 15, 2021 after enrolling in PROSPERO (CRD42021220269). Studies evaluating the association between PLR on admission and outcomes in terms of mortality and severity among COVID-19 patients were included. We retrieved 32 studies, with a total of 2768 and 3262 COVID-19 patients for mortality and disease severity outcomes. Deceased and critically ill patients had higher PLR levels on admission in comparison to survivors and non-severe patients (mean differences [MD] = 66.10; 95% confidence interval [CI]: 47.75-84.44; p < 0.00001 and MD = 86.74; 95% CI: 67.7-105.7; p < 0.00001, respectively). A higher level of PLR on admission in COVID-19 patients is associated with increased morbidity and mortality. However, the evidence is of low quality and further studies regarding the cut-off value of PLR are the need of the hour.
