The value of anal swab RT-PCR for COVID-19 diagnosis in adult Indonesian patients

Abstract

ObjectiveThis study will test the performance of the anal swab PCR test when compared with the nasopharyngeal swab PCR test as a diagnostic tool for COVID-19.DesignAn observational descriptive study which included hospitalised suspected, or probable cases of hopitalised COVID-19 patients, conducted in Dr. Cipto Mangunkusumo National Hospital, Ciputra Hospital, Mitra Keluarga Depok Hospital and Mitra Keluarga Kelapa Gading Hospital, Indonesia. Epidemiological, clinical, laboratory and radiology data were obtained. Nasopharyngeal and anal swabs specimens were collected for SARS-CoV-2 RNA detection.ResultsWe analysed 136 subjects as part of this study. The clinical spectrum of COVID-19 manifesation in this study was typical of hospitalised patients, with 25% classified as mild cases, 14.7% in severe condition and 12.5% of subjects classified as having acute respiratory distress syndrome. When compared with nasopharyngeal swab as the standard specimen for reverse transcription polymerase chain reaction (RT-PCR) detection of SARS-CoV-2 antigen, the sensitivity and specificity of the anal swab was 36.7% and 93.8%, respectively. The positive and negative predictive value were 97.8% and 16.5 %, respectively. The performance of the anal swab remained similar when only the subgroup of patients with gastrointestinal symptoms (n=92, 67.6%) was analysed (sensitivity 40% and specificity 91.7%). Out of all the subjects included in analysis, 67.6% had gastrointestinal symptoms. Similarly, 73.3% of patients in the anal swab-positive group had gastrointestinal symptoms. The two most common gastrointestinal symptoms in the subjects’ population were nausea and anorexia.ConclusionAnal swab specimen has low sensitivity (36.7%) but high specificity (93.8%) for detecting SARS-CoV-2 antigen by RT-PCR. Only one additional positive result was found by anal swab among the nasopharyngeal swab-negative group. Anal swab may not be needed as an additional test at the beginning of a patient’s diagnostic investigation and nasopharyngeal swab RT-PCR remains as the standard diagnostic test for COVID-19.

A Comparative Study Between Nasopharyngeal/Oropharyngeal, Faecal and Saliva Viral Shedding In Ghanaian COVID-19 Patients attending Komfo Anokye Teaching Hospital (KATH), Kumasi from October – December, 2020

“…The sensitivity and specificity of faecal samples as compared to pharyngeal samples obtained from this study goes to affirm that indeed, faecal samples could possibly be used in place of pharyngeal samples. This agreed with other studies carried out by Abdullah M et al, (2021) and Jeong et al, (2020) when it comes to the sensitivity and specificity of using faeces to test for the presence of SARS-CoV 2.…”

SARS-CoV-2: Reinfection after 18 Months of a Previous Case with Multiple Negative Nasopharyngeal Swab Tests and Positive Fecal Molecular Test

“…Real-time quantitative reverse transcriptase-polymerase chain reaction (RT-qPCR) is the gold-standard laboratory technique for the identification of SARS-CoV-2 in the clinical setting, and nasopharyngeal swabs are considered the primary sample for COVID-19 tests with a sensitivity of around 70–80% [ 38 , 39 , 40 ]. However, false negative results are also possible [ 38 , 41 ], and other specimens, including fecal viral testing that has a high specificity to detect SARSCoV-2 despite a low sensitivity ranging from 37% to 60%, have also been considered [ 42 , 43 ]. However, some studies demonstrated that the clearance time of COVID-19 in the digestive tract was later than that in the respiratory tract [ 44 , 45 ].…”

SARS-CoV-2 detection methods: A comprehensive review

“…Few studies used anal swabs to diagnose COVID-19 ( Abdullah et al, 2021 , Li et al, 2021 ). However, it is not recommended to be used as a standalone test.…”

“…The abovementioned specimen types are variable for their diagnostic accuracy; sample collection or handling, the amount of viral load in the specimen, severity, or time from the onset of infection are all factors that would affect the accuracy of diagnosis ( Coden et al, 2020 , Abdullah et al, 2021 , Ling et al, 2020 , Senok et al, 2020 ). Some researchers noticed variabilities when testing different specimens from the same patient ( Li et al, 2021 , Xiao et al, 2020 , Senok et al, 2020 ).…”