ABSTRACT
Rapid diagnostic tests (RDTs) significantly impact disease treatment strategy. In Japan, information on the use of RDTs for patients with COVID-19 is limited. Here, we aimed to investigate the RDT implementation rate, pathogen detection rate, and clinical characteristics of patients positive for other pathogens by using COVIREGI-JP, a national registry of hospitalized patients with COVID-19. A total of 42,309 COVID-19 patients were included. For immunochromatographic testing, influenza was the most common (n = 2881 [6.8%]), followed by Mycoplasma pneumoniae (n = 2129 [5%]) and group A streptococcus (GAS) (n = 372 [0.9%]). Urine antigen testing was performed for 5524 (13.1%) patients for S. pneumoniae and for 5326 patients (12.6%) for L. pneumophila. The completion rate of M. pneumonia loop-mediated isothermal amplification (LAMP) testing was low (n = 97 [0.2%]). FilmArray RP was performed in 372 (0.9%) patients; 1.2% (36/2881) of patients were positive for influenza, 0.9% (2/223) for the respiratory syncytial virus (RSV), 9.6% (205/2129) for M. pneumoniae, and 7.3% (27/372) for GAS. The positivity rate for urine antigen testing was 3.3% (183/5524) for S. pneumoniae and 0.2% (13/5326) for L. pneumophila. The positivity rate for LAMP test was 5.2% (5/97) for M. pneumoniae. Five of 372 patients (1.3%) had positive FilmArray RP, with human enterovirus being the most frequently detected (1.3%, 5/372). The characteristics of patients with and without RDTs submission and positive and negative results differed for each pathogen. RDTs remain an important diagnostic tool in patients with COVID-19 in whom coinfection with other pathogens needs to be tested based on clinical evaluation.