Routine laboratory tests: Potential practical parameters to detect coronavirus disease-2019 in resource-limited settings

Introduction: The diagnosis of Coronavirus Disease-2019 (COVID-19), an ongoing global pandemic with more than 3 million cases worldwide both in developed and developing countries, requires molecular or serological tests that are not available in some settings. This systematic review provides further evidence to assess the diagnostic accuracy of routine laboratory tests to detect COVID-19 in suspected COVID-19 patients in resource-limited point of care and mobile laboratory. Methodology: Comprehensive and systematic literature search in electronic databases (PubMed, Cochrane, and Online Wiley Library) was conducted to retrieve studies published between December 2019 and April 2020 reporting the diagnostic value of routine laboratory tests in the diagnosis of COVID-19. The quality of each study was assessed using QUADAS2. Literature search and study selection were depicted in PRISMA 2009 Flow Diagram. Results: Three studies were included in this review. Two studies reported poor accuracy (AUC 0.075 and 0.624) of lymphopenia to detect COVID-19. One study reports good accuracy (AUC 0.858) of neutrophilia to detect COVID-19 amongst suspected cases. One multi-gated cross-sectional study reports poor discriminatory ability (AUC 0.65) of neutrophilia to discriminate between COVID-19 and CAP. Because of its big variability between patients and poor diagnostic accuracy (AUC 0.112 and 0.624), leukocyte count should not be a single parameter to determine COVID-19 patient status. Conclusions: Neutrophil percentage might be helpful to determine COVID-19 status for suspected patients at the primary point of care or even in a mobile laboratory for countries with limited resources, but further study is needed to support this statement.