Evaluation of rapid molecular POCT (POCT X) for detection of influenza A/B virus and respiratory syncytial virus in comparison to multiplex PCR / Wan Azlirull Aini Ahmad Ghazali

BACKGROUND: Influenza A, B and Respiratory Syncytial Virus are highly infectious and are the most prevalent infective agents of acute respiratory infection. Morbidity and mortality are high in young children, the elderly and those who are immunocompromised. Antiviral treatment for influenza infection is beneficial if it is given within 48 hours of symptoms, while antiviral treatment for Respiratory Syncytial Virus infection is reserved for severe disease and transplant patients. However, as early clinical symptoms are non-specific flu-like illness, initial presentations to the primary care clinic will not be able to confirm the diagnosis without sending patient’s specimen to the bigger laboratory, which will take time and delay antiviral commencement and patient isolation. The development of a sensitive, specific and easy to use point-of-care testing will enable clinician to perform the test in the clinic, confirm the diagnosis early and allow early treatment, avoid disease progression and further complications, as well as advise patient isolation to limit spread of infection.
OBJECTIVE: This study aims to evaluate the performance (sensitivity and specificity) of a rapid molecular point-of-care testing for Influenza A virus, Influenza B virus and RSV, using a multiplex PCR as the method of reference.
METHODS: A cross sectional study on the evaluation of a rapid molecular POCT (POCT X) in comparison to multiplex PCR was conducted for the detection of Influenza A, B and RSV viruses. 120 nasopharyngeal swabs were recruited from Microbiology Laboratory, Department of Pathology, Hospital Sungai Buloh, and Quantum Diagnostic Gribbles Pathology Laboratory, Petaling Jaya Selangor, Malaysia from November 2019 to October 2020. 31 specimens out of 120 were served as control and all these had none of the above stated three viruses detected. The inclusion criteria for the specimens to be processed includes nasopharyngeal swabs that was tested positive for influenza viruses and RSV. Meanwhile the exclusion criteria were insufficient volume of viral transport media and specimens other than nasopharyngeal swabs. Demographic data that are age and gender were collected. The specimens were tested using both method; rapid molecular POCT X and multiplex PCR. Descriptive analysis was performed for the demographic data, while specificity, sensitivity, positive predictive value and negative predictive values were calculated.
RESULTS: 119 specimens were included in this study. Male to female ratio was 1:1.6. The age range was five months to 82 years old, with the mean of 33 years old. For POCT X, influenza A virus was detected in 54 specimens (46.6%), while ten specimens (8.6%) had influenza B virus detected and RSV were detected in 11 specimens (9.5%). Multiplex PCR were able to detect Influenza A virus in 62 (53.5%) specimens, Influenza B virus were detected in 12 (10.3%) specimens and RSV were detected in 11 (9.5%) specimens. There were ten specimens (n=10) demonstrated discordant results where POCT X was not able to detect eight (12.9%) and two (16.7%) influenza A and B viruses respectively. While for RSV, the POCT X managed to achieve 100% agreement on the detection of RSV. The CT values for the discordant result was obtained from multiplex PCR; that varies from 17.8 to 42.69. The sensitivity of POCT X using multiplex PCR as method of reference in detecting Influenza A virus was 87% with the specificity of 100%, with positive predictive value (PPV) of 0.96, and negative predictive value (NPV) of one. The sensitivity of POCT X in detecting Influenza B virus was 83.3% with 100% specificity, with PPV of 0.56 and NPV of one. The overall sensitivity for Influenza virus detection using POCT X was 86.5%, and specificity of 100%. The sensitivity and specificity of POCT X in detecting RSV was at 100%, and the PPV and NPV were equally one. The correlation of POCT X to multiplex PCR was statistically significant for Influenza A and B with p<0.05. However for RSV, the targeted sample size of at least 12 positive results was not achieved, making p > 0.05.
CONCLUSIONS Our study concluded that the performance of POCT X is comparable to other rapid molecular testing for influenza virus and RSV that are available in the market. The test does not require a highly trained personnel and is able to give result in 13 minutes, making it suitable to be placed in the primary care clinic and emergency department.