Diagnostic value of antibody testing in comparison with lung scan and PCR in patients suspected of having COVID-19

Kiana Shirani; Milad Hajihashemi; Ashkan Mortazavi; Alireza Assadi; Azar Baradaran; Behrooz Ataei; Hossein Badei

doi:10.18502/ijm.v16i4.16310

Kiana Shirani Department of Infectious Diseases, Nosocomial Infection Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
Milad Hajihashemi Department of Infectious Diseases, Immunodeficiency Diseases Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
Ashkan Mortazavi Department of Infectious Diseases, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
Alireza Assadi Department of Infectious Diseases, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
Azar Baradaran Department of Pathology, Isfahan University of Medical Sciences, Isfahan, Iran
Behrooz Ataei Department of Infectious Diseases, Infectious Diseases and Tropical Medicine Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
Hossein Badei Department of Infectious Diseases, Infectious Diseases and Tropical Medicine Research Center, Isfahan University of Medical Sciences, Isfahan, Iran

DOI: https://doi.org/10.18502/ijm.v16i4.16310

Keywords: COVID-19; SARS-CoV-2 virus; COVID-19 serological testing; COVID-19 reverse transcription polymerase chain reaction; Computed tomography scan; X-ray

Abstract

Background and Objectives: SARS-CoV-2 is a newly discovered viral infection. It’s still unclear how antibodies react in infected individuals, and there is not enough evidence to support the clinical use of antibody examination. This study evalu- ates the diagnostic value of serologic tests for diagnosing COVID-19.

Materials and Methods: 32 patients for whom serologic testing was performed within 7 to 21 days from symptom onset and whether they were diagnosed with COVID-19 by both PCR and lung HRCT as gold standard tests at the same time, were included in the study.

Results: Serologic tests (IgM / IgG) compared to PCR and lung HRCT scan to diagnose COVID-19, were 89.3% specific and 59.6% sensitive. Positive predictive value (PPV) was 95% and negative predictive value (NPV) was 37%. The diagnostic accuracy index of the serologic test was 0.745 (CI 0.651-0.838) (p-value <0.001).

Conclusion: Serologic testing can be a complementary alternative for SARA-CoV-2 nucleic acid RT-PCR, although it can- not replace it completely. IgG/IgM combo test kits and RT-PCR together can give more insight into the diagnosis of SARS- CoV-2.