Blood markers (lymphocyte percentages, neutrophils, CRP and ESR) can help in prioritizing rRT-PCR test for suspected COVID-19 patients in countries with limited health resources

INTRODUCTION: the outbreak of coronavirus disease 2019 (COVID-19) started in China in December 2019 and spread causing more than 14 million cases all over the world on July 19(th), 2020. Although, real-time reverse transcription polymerase chain reaction (rRT-PCR) test is the gold standard test, it needs a long time and requires specialized laboratories and highly trained personnel. All these difficulties forced many countries with reduced health resources to limit rRT-PCR tests to individuals with severe symptoms. Thus, routine blood marker that may help physicians to suspect COVID-19 and hence, prioritize patients for molecular diagnosis is badly needed. METHODS: fifty-six Sudanese COVID-19 patients admitted to Jabra hospital were included in this study. For all the patients we analyzed complete blood count (CBC), CBC, plasma levels of C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), liver function tests (LFT) and renal function tests (RFT). Statistical analysis was done using SPSS program with a significance level of p≤0.05 and confidence limits (CLs) 95%. The difference between groups was tested using Mann-Whitney test was for quantitative variables while qualitative variables was tested using chi-square (Fisher exact) test. RESULTS: the result shows that, 35 out of the 56 patients (62.5%) were male and 21 (37.5%) were females with a median age of 60-year-old for both sexes. Lymphocytes % showed decrease to 9.2 (P-value=0.000) and significant increase in neutrophils to 83.05 (P-value=0.005), ESR to 65.54 (P-value=0.000) and CRP to 91.07 (P-value=0.000). The receiver operating characteristic curve (ROC)/area under the curve (AUC) ensured the expellant result of lymphocytes % as a predictor with 92% area under the curve, neutrophils were 90% and ESR 95.8%. The percent of detecting COVID-19 positive RT-PCR (98%) for suspected individuals using ROC showed best cutoff of ≤21.8 for lymphocytes %, ≥67.7 for neutrophils, ≥37.5 for ESR, ≥6.2 for CRP and ≥7.15 for WBCs. CONCLUSION: the results also showed that, lymphocyte percentages, neutrophils, CRP and ESR may be used as markers for COVID-19 helping prioritizing individuals for rRT-PCR test.