COVID-19-specific prefectural hospital bed utilization rate and in-hospital mortality among COVID-19 patients throughout the first three years of the pandemic in Japan.

BACKGROUND

We examined the association between the COVID-19-specific prefectural bed utilization rate and in-hospital mortality during the first three years of the pandemic in Japan.

METHODS

This nationwide study included 58,175 COVID-19 patients from the COVID-19 Registry Japan, hospitalized between May 1, 2020 and November 30, 2022. Based on the weekly COVID-19-specific bed utilization rate in each prefecture at diagnosis, patients were categorized into four groups (< 25%, 25% to < 50%, 50% to < 75%, and ≥ 75%). Odds ratios (ORs) were estimated by fitting a generalized linear mixed model with prefecture as a random intercept and adjusting for covariates (age, gender, body mass index, smoking and drinking status, and comorbidities). Additional analyses according to age group, gender, and wave of the pandemic were conducted.

RESULTS

We observed 2312 (4.0%) all-cause in-hospital deaths. All-cause in-hospital mortality increased with higher COVID-19 bed utilization rates at diagnosis (OR for multivariable model 1.35, 95% confidence interval [CI] 1.19-1.54 for 25% to <50%; 1.89, 1.66-2.16 for 50 to <75%; 2.16, 1.80-2.58 for ≥75%; P for trend<0.0001). Stronger associations were noted among the younger population (aged <70 years, OR: 3.18, 1.96-5.19) and during the fourth (March 1-June 30, 2021, OR: 3.81, 2.13-6.80) and sixth pandemic waves (January 1-Jun 30, 2022, OR: 2.67, 1.68-4.23).

CONCLUSIONS

Our results emphasize that preventing hospital bed shortages during outbreaks is an important public health strategy to reduce the associated mortality, particularly when new strains emerge and in younger people.