Factors affecting the sensitivity of quantitative severe acute respiratory syndrome coronavirus 2 antigen test.

INTRODUCTION: The accuracy of nucleic acid amplification tests (NAATs) is affected by various factors; however, studies examining the factors affecting the accuracy of quantitative severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigen test (QAT) are limited. METHODS: A total of 347 nasopharyngeal samples were collected from patients with coronavirus disease 2019 (COVID-19), and the date of onset was obtained from the electronic medical records. The SARS-CoV-2 antigen level was measured using Lumipulse Presto SARS-CoV-2 Ag (Presto), while NAAT was performed using the Ampdirect 2019-nCoV Detection Kit. RESULTS: Presto had a sensitivity rate of 95.1% (95% confidence interval: 92.8-97.4) in detecting the SARS-CoV-2 antigen in 347 samples. The number of days from symptom onset to sample collection was negatively correlated with the amount of antigen (r = -0.515) and sensitivity of Presto (r = -0.711). The patients' age was lower in the Presto-negative samples (median age, 39 years) compared with that in the Presto-positive samples (median age, 53 years; p < 0.01). A significant positive correlation was observed between age (excluding teenagers) and Presto sensitivity (r = 0.764). Meanwhile, no association was found between the mutant strain, sex, and Presto results. CONCLUSION: Presto is useful for the accurate diagnosis of COVID-19 owing to its high sensitivity when the number of days from symptom onset to sample collection is within 12 days. Furthermore, age may affect the results of Presto, and this tool has a relatively low sensitivity in younger patients.

Preoperative predictors of extended resection in patients with complicated acute appendicitis undergoing surgery.

Background : Appendectomy can be challenging and occasionally converted to extensive resection for complicated appendicitis. However, optimal treatment strategies can be developed using preoperative risk assessment. Thus, we aimed to investigate the preoperative predictors of extensive resection in complicated appendicitis patients undergoing surgery. Materials and methods : In total, 173 complicated appendicitis patients undergoing surgery between 2014 and 2019 were classified into the appendectomy (n = 153) or extensive resection (n = 20) groups. Clinicopathological factors and surgical outcomes were compared between groups. Results : Extensive resection was performed in 20 of 173 complicated appendicitis patients (11.5%). The rates of having defects in the wall structure at the appendix root on computed tomography images were significantly higher, and the duration from onset to surgery was significantly longer in the extensive resection group. Significant differences were found in operative duration, blood loss and postoperative hospitalization, but none in the incidence of postoperative complications between groups. Multivariate analyses showed that defects in the wall structure at the appendix root and five days or longer from onset were identified as independent predictors of extensive resection. Conclusions : Defects in the wall structure at the appendix root and five days or longer from onset predict extensive resection performance in complicated appendicitis patients. J. Med. Invest. 68 : 334-341, August, 2021.