Validation of predictors of disease severity and outcomes in COVID-19 patients: a descriptive and retrospective study

Abstract Background The severity and outcome of COVID-19 cases has been associated with percentage of circulating lymphocytes (LYM%), levels of C-reactive protein (CRP), interleukin 6 (IL-6), procalcitonin (PCT), lactic acid (LA) and viral load (ORF1ab Ct). However, the predictive power of each of these indicators in disease classification and prognosis remains largely unclear. Methods we retrospectively collected information on the above parameters in 142 patients with COVID-19, stratifying them by survival or disease severity. Findings CRP, PCT, IL-6, LYM% and ORF1ab Ct were significantly altered between survivors and non-survivors. LYM%, CRP and IL-6 were the most sensitive and reliable factors in distinguishing between survivors and non-survivors. These indicators were significantly different between critically ill and severe/moderate patients. Only LYM% levels were significantly different between severe and moderate types. Among all the investigated indicators, LYM% was the most sensitive and reliable in discriminating between critically ill, severe and moderate types, and between survivors and non-survivors. Conclusions CRP, PCT, IL-6, LYM% and ORF1ab Ct, but not LA, could predict prognosis and guide classification of COVID-19 patients. LYM% was the most sensitive and reliable predictor for disease typing and prognosis. We recommend that LYM% be further investigated in the management of COVID-19.