BackgroundStudies on the impact of coronavirus disease 2019 (COVID-19) on people’s routine medical care are limited, and understanding the factors associated with medical care avoidance can inform us about the ongoing pandemic.ObjectivesWe aimed to assess the impact of Japan’s state of emergency and stay-at-home policy for COVID-19 on hospital visits and disease exacerbation; we also identified related factors.MethodsThis cross-sectional study used data from the Japan COVID-19 and Society Internet Survey (JACSIS), which included randomly sampled research agency panellists in Japan. Among the 28,000 participants, we included 7,747 respondents who reported having any disease. We described baseline characteristics and avoidance-related hospital visit outcomes. We used multivariable logistic regression analyses to assess the association between chronic diseases and outcomes of hospital visit avoidance.ResultsAmong 7,747 participants, 17.7% of patients with chronic diseases avoided hospital visits, 2.1% of patients postponed hospitalization or surgery, 4.9% of patients ran out of drug, and 5.3% of patients experienced disease exacerbation during the COVID-19 pandemic in April and May 2020. Exacerbations occurred mostly in participants with mental diseases, chronic pain and headache, and diabetes (OR 3.33 [95% confidence interval (CI): 2.51–4.41], 2.83 [95% CI: 2.19–3.66], and 1.53 [95% CI: 1.10–2.13], respectively). Patients with cardiovascular disease or cancer did not experience exacerbation [OR 0.55 (95% CI: 0.31–0.97), 0.79 (95% CI: 0.43–1.45)].ConclusionsThe rates of hospital visit avoidance and exacerbation varied among patients with different diseases under the COVID-19 stay-at-home policy in April and May 2020, and disease-specific preparedness may be necessary for the pandemic.