Correlating CT Chest with RT-PCR in Diagnosing COVID-19: Experience at a Tertiary Health Care Hospital in Pakistan

Objective: To establish the accuracy of computed tomography(CT) chest in the diagnosis of COVID-19 pneumonia by taking reverse transcriptase-polymerase chain reaction(RT-PCR) as a reference standard and to analyze discordant CT chest and RT-PCR results.Materials and Methods: A retrospective cross-sectional study of patients presented to a tertiary health care hospital in Punjab, Pakistan for CT examination with suspicion of COVID-19 from April 1, to June 30, 2020. Each CT chest was categorized as positive/negative for COVID-19 pneumonia and the results were compared with the RT-PCR test. Discordant CT chest and PCR results were also investigated.Results: The study population had a mean age of 48 years ± 6.6 years with 54.5% males and 45.4% females. Sensitivity(Sn), specificity (Sp), positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy of CT in diagnosing COVID-19 pneumonia taking RT- PCR as the gold standard was 92.5%, 46.6%%, 82.2%, 70%, and 80% respectively. Conclusion: CT chest has high sensitivity but modest specificity in the diagnosis of COVID-19 pneumonia. It can be employed as an adjunctive screening and diagnostic test for early diagnosis of disease in places where disease prevalence is high.