Predictive Value of C–reactive Protein, Lactate Dehydrogenase, Ferritin and D-dimer Levels in Diagnosing COVID-19 Patients: a Retrospective Study

BACKGROUND: Since December 2019. millions of people in the world have been affected with the novel Coronavirus disease-2019 (COVID-19) pandemic, and high economic impact has affect many countries especially low socioeconomic one like Iraq due to the high cost and limited availability of RT-PCR for diagnosis of COVID-19, so there should be predictive low cost easily available laboratory tests that can be used before proceeding to the high cost techniques. OBJECTIVE: In this retrospective study we aimed to evaluate the diagnostic accuracy of CRP, ferritin, LDH and D-dimer in predicting positive cases of COVID-19 in Iraq. METHODS: It is a retrospective observational cohort study based on STARD guidelines to determine the diagnostic accuracy of (CRP, LDH, ferritin and D dimer) for COVID-19 of electronic medical records of private medical center in Najaf city, at which 566 individuals were recruited. The investigated subjects were either in close contact with previously COVID-19 positive patients or have one or more symptoms of COVID-19. They were categorized into 2 groups, 205 subjects diagnosed with RT-PCR as COVID-19 negative, and 361 COVID-19 positive patients, results of study variables of the cohort were recruited from the medical records. RESULTS: Combining of these parameters had the following findings: CRP + ferritin; AUC: 0.77 with 55% sensitivity and 97% specificity, Ferritin + LDH; AUC: 0.83 with 65% sensitivity and 92% specificity, CRP+LDH; AUC: 0.78 with 56% sensitivity and 98% specificity, CRP + LDH + ferritin; AUC: 0.85, with 73% sensitivity and 88% specificity, CRP + LDH + ferritin + D dimer; AUC: 0.85 75% sensitivity and 87% specificity. CONCLUSION: Combination of routine laboratory biomarkers (CRP, LDH and ferritin ±D dimer) can be used to predict the diagnosis of COVID-19 with an accepted sensitivity and specificity before proceeding to definitive diagnosis by RT-PCR.