tetano
Editor, Senior Moderator
Infect Chemother
. 2021 Sep 21;S1341-321X(21)00260-9.
doi: 10.1016/j.jiac.2021.09.011. Online ahead of print.
Comparative study of SmartAmp assay and reverse transcription-polymerase chain reaction by saliva specimen for the diagnosing COVID-19
Nobuhiro Asai[SUP] 1 [/SUP], Akiko Nakamura[SUP] 2 [/SUP], Daisuke Sakanashi[SUP] 2 [/SUP], Isao Koita[SUP] 2 [/SUP], Wataru Ohashi[SUP] 3 [/SUP], Yuzuka Kawamoto[SUP] 2 [/SUP], Narimi Miyazaki[SUP] 2 [/SUP], Tomoko Ohno[SUP] 2 [/SUP], Atsuko Yamada[SUP] 2 [/SUP], Sumie Chida[SUP] 2 [/SUP], Yuichi Shibata[SUP] 2 [/SUP], Arufumi Shiota[SUP] 4 [/SUP], Hideo Kato[SUP] 5 [/SUP], Mao Hagihara[SUP] 6 [/SUP], Yuka Yamagishi[SUP] 2 [/SUP], Hirotoshi Ohta[SUP] 2 [/SUP], Hiroshige Mikamo[SUP] 7 [/SUP]
Affiliations
Abstract
Introduction: The pandemic of a novel coronavirus disease 2019 (COVID-19) caused by a severe acute respiratory coronavirus 2 (SARS-CoV-2) infection has been problematic worldwide. A new SARS-CoV-2 diagnostic test (SmartAmp) was licensed in Japan in July 2021. This method, which enables us to diagnose COVID-19 as well as a gene mutation on the virus, is promising to reduce medical costs and staff labor.
Patients and methods: To analyze the diagnostic accuracy of the SmartAmp assay for diagnosing COVID-19, we performed this retrospective study at our institute during April and May 2021. We compared the results of the SmartAmp assay and real-time reverse transcription-polymerase chain reaction (rRT-PCR) using a saliva sample from individuals suspected as having COVID-19.
Results: Out of 70 samples tested, the SmartAmp assay had 50 (71%) positive and 20 (29%) negative results. Using rRT-PCR as a reference, the diagnostic accuracy displayed a sensitivity of 84%, a specificity of 95%, a positive predictive value of 97.7%, and a negative predictive value of 70.4%. On the other hand, false-negative cases were found in 7 (10%), and there was no significant difference of Ct-value between true positive and false negative cases (Mean Ct-value 25.2 vs. 27.5 cycles, p = 0.226 by Mann-Whitney U test).
Conclusion: The SmartAmp assay is a valuable method to diagnose COVID-19 rapidly. However, the negative predictive value is not high enough to diagnose the disease, so that negative results should be considered for rRT-PCR testing if patients are suspected of having COVID-19.
Keywords: COVID-19; Coronavirus; Reverse transcription-polymerase chain reaction; SARS-CoV-2; SmartAmp.
. 2021 Sep 21;S1341-321X(21)00260-9.
doi: 10.1016/j.jiac.2021.09.011. Online ahead of print.
Comparative study of SmartAmp assay and reverse transcription-polymerase chain reaction by saliva specimen for the diagnosing COVID-19
Nobuhiro Asai[SUP] 1 [/SUP], Akiko Nakamura[SUP] 2 [/SUP], Daisuke Sakanashi[SUP] 2 [/SUP], Isao Koita[SUP] 2 [/SUP], Wataru Ohashi[SUP] 3 [/SUP], Yuzuka Kawamoto[SUP] 2 [/SUP], Narimi Miyazaki[SUP] 2 [/SUP], Tomoko Ohno[SUP] 2 [/SUP], Atsuko Yamada[SUP] 2 [/SUP], Sumie Chida[SUP] 2 [/SUP], Yuichi Shibata[SUP] 2 [/SUP], Arufumi Shiota[SUP] 4 [/SUP], Hideo Kato[SUP] 5 [/SUP], Mao Hagihara[SUP] 6 [/SUP], Yuka Yamagishi[SUP] 2 [/SUP], Hirotoshi Ohta[SUP] 2 [/SUP], Hiroshige Mikamo[SUP] 7 [/SUP]
Affiliations
- PMID: 34580006
- DOI: 10.1016/j.jiac.2021.09.011
Abstract
Introduction: The pandemic of a novel coronavirus disease 2019 (COVID-19) caused by a severe acute respiratory coronavirus 2 (SARS-CoV-2) infection has been problematic worldwide. A new SARS-CoV-2 diagnostic test (SmartAmp) was licensed in Japan in July 2021. This method, which enables us to diagnose COVID-19 as well as a gene mutation on the virus, is promising to reduce medical costs and staff labor.
Patients and methods: To analyze the diagnostic accuracy of the SmartAmp assay for diagnosing COVID-19, we performed this retrospective study at our institute during April and May 2021. We compared the results of the SmartAmp assay and real-time reverse transcription-polymerase chain reaction (rRT-PCR) using a saliva sample from individuals suspected as having COVID-19.
Results: Out of 70 samples tested, the SmartAmp assay had 50 (71%) positive and 20 (29%) negative results. Using rRT-PCR as a reference, the diagnostic accuracy displayed a sensitivity of 84%, a specificity of 95%, a positive predictive value of 97.7%, and a negative predictive value of 70.4%. On the other hand, false-negative cases were found in 7 (10%), and there was no significant difference of Ct-value between true positive and false negative cases (Mean Ct-value 25.2 vs. 27.5 cycles, p = 0.226 by Mann-Whitney U test).
Conclusion: The SmartAmp assay is a valuable method to diagnose COVID-19 rapidly. However, the negative predictive value is not high enough to diagnose the disease, so that negative results should be considered for rRT-PCR testing if patients are suspected of having COVID-19.
Keywords: COVID-19; Coronavirus; Reverse transcription-polymerase chain reaction; SARS-CoV-2; SmartAmp.