Association of laboratory biomarkers – serum albumin, C-reactive protein, lactate dehydrogenase and D-dimer with severity of COVID-19 infections

To assess the association of laboratory biomarkers- serum albumin, C-reactive protein, lactate dehydrogenase and D-dimer with severity of COVID-19 infections and to know the value of individual parameters in assessing severity of COVID-19 infection. A prospective observational study was conducted on COVID-19 patients of age above 18 years, admitted to a tertiary care center in coastal part of southern India. The laboratory parameters mentioned, were estimated and compared between groups i.e. severe and non-severe COVID-19. Their cut-off values were detected using the receiver-operator curve.
Totally 577 patients with a mean age of 55±16.21 years were included. Among them, 52.3% of the patients suffered from severe COVID-19 infection and 47.6% of the cases had non-severe COVID-19 infection.
The median C-reactive protein, median lactate dehydrogenase and median D-dimer levels were significantly higher in patients with severe COVID-19 compared to patients with non-severe COVID-19 (64.93 mg/dL vs. 10.23 mg/dL, (393 U/L vs 249 U/L) and (0.9 µg/mL vs 0.5 µg/mL) respectively. Univariate logistic regression analysis showed that the odd’s ratio of serum albumin, C-reactive protein, lactate dehydrogenase and D-dimer were 0.486 (p≤0.001, 95% CI= 0.361-0.653), 1.005 (p≤0.001, 95% CI=1.003-1.008), 1.005 (p≤0.001, 95% CI=1.004-1.006) and 3.847 (p≤ 0.001, 95% CI=2.702- 5.476). Both C-reactive protein and lactate dehydrogenase at a cutoff value of 22.5 mg/dL (0.746AUC) and 331U/L had good sensitivity and specificity in predicting severe COVID-19 infection. Multivariate logistic regression analysis showed that C-reactive protein (OR=1.004, P≤0.001), lactate dehydrogenase (OR=1.005, p≤0.001) and D-dimer (OR=1.208, p≤0.001) were statistically significant independent predictors of severity of COVID-19.
The laboratory biomarkers like C-reactive protein, lactate dehydrogenase and D-dimer can be used for predicting severe COVID-19 infections at admission. C-reactive protein, lactate dehydrogenase and Ddimer could be used in differentiating non-severe and severe COVID-19 infections with their cut off values being >22.54 mg/mL, >331 U/L and >0.5 µg/mL respectively