Risk Factors for COVID-19 Infection in Adult Patients: A Retrospective Observational Study in Japan

Purpose: The aim of the study was to identify the characteristics of patients infected with coronavirus disease 2019 (COVID-19) and to determine risk factors for COVID-19 infection in Japanese patients. Patients and Methods: We conducted a single-center retrospective observational study in Japanese adult patients (>= 20 years) who visited Kenwakai Hospital (Nagano Japan). We analyzed data of 378 patients (mean age, 75 +/- 14 years; men, 54%) from the hospital's electronic information system. COVID-19 was diagnosed by polymerase-chain reaction. Patients were divided into 2 groups based on diagnosis of COVID-19. Results: Patients infected with COVID-19 showed significantly higher rates of men (69.8 vs 51.6%, P = 0.025) than uninfected control patients. After adjustment for possible confounding factors, COVID-19 infection was significantly associated with BUN (odds ratio [OR], 1.02; 95% confidence interval [CI], 1.01-1.03) and serum creatinine (Scr) (OR, 1.14; 95% CI, 1.05-1.24). This association was observed in men (BUN, P = 0.012; Scr, P = 0.012), but not in women (BUN, P = 0.43; Scr, P = 0.54). Conclusion: BUN and Scr are potential risk factors for infection of COVID-19 in Japanese patients, particularly in men. Our results suggest that renal parameters might be important in Japanese male patients for the early detection of COVID-19 infection.