Effects of night-time and weekend admissions on in-hospital mortality in acute myocardial infarction patients in Japan

BACKGROUND Patients admitted to hospital during off-hours may experience poorer quality of care and clinical outcomes. However, few studies have examined the variations in clinical processes and outcomes across admission times and days of the week in acute myocardial infarction (AMI) patients. This study aimed to comparatively analyze the effect of weekend and weekday admissions stratified by admission time on in-hospital mortality in AMI patients. METHODS AND RESULTS Using a large nationwide administrative database, we analyzed 103,908 AMI patients admitted to 639 Japanese acute care hospitals between April 2011 and March 2015. We divided patients into the following 4 groups: weekday daytime admissions, weekday night-time admissions, weekend daytime admissions, and weekend night-time admissions. A hierarchical logistic regression model was used to comparatively examine in-hospital mortality among the groups after adjusting for age, sex, ambulance use, Killip class, comorbidities, and the number of cardiologists in the admitting hospital. In addition, we also calculated and compared the adjusted odds ratios of various AMI therapies among the groups. The in-hospital mortality rate of weekend daytime admissions was higher than those admitted during other times (weekday daytime: 6.8%; weekday night-time; 6.5%, weekend daytime; 7.6%; weekend night-time: 6.6%; P < 0.001), even after adjusting for the covariates (adjusted odds ratio for weekend daytime admissions: 1.10; 95% confidence interval: 1.03-1.19). The prescription rates of guideline-based medications provided on the first day of admission were higher in night-time admissions than in daytime admissions. CONCLUSIONS In-hospital mortality rates were higher in AMI patients admitted during weekend daytime hours when compared with patients admitted during other times. Furthermore, patients admitted during daytime hours had lower prescription rates of guideline-based medications. Our findings indicate that weekend daytime admissions may be a potential target for improvement in the Japanese healthcare system.