Hospital volumes and outcomes for inpatients with acute myocardial infarction in Shanxi, China: an observational study

Abstract

BackgroundMany studies have examined the relationship between hospital volume and outcomes for inpatients with acute myocardial infraction (AMI) in developed countries. However, very few studies of this relationship have been conducted for inpatients with AMI in China. This study aimed to assess the relationship between hospital volume and clinical outcomes for inpatients with AMI in Shanxi, China. MethodsData from a total of 15 747 patients with AMI who were treated in 56 hospitals in Shanxi, China, were analysed. Hospital volume was defined as the number of inpatients with AMI in 2015 at each hospital, and hospitals were sorted into three groups by volume (low volume [<385 inpatients], medium volume [385–637 inpatients], and high volume [>637 inpatients]). Patient and hospital characteristics were adjusted using multivariable logistic regression and linear regression, and the relationships between hospital volume and in-hospital mortality, length of stay, and total hospitalization costs were assessed for inpatients with AMI. FindingsThe crude in-hospital mortality rate was 1.93% among the 15 747 patients with AMI. Adjusted in-hospital mortality among AMI patients was significantly lower for medium-volume hospitals (odds ratio [OR] 0·605, 95% CI 0·411–0·900) compared to low-volume hospitals, whereas no significant difference was found between low-volume hospitals and high-volume hospitals (0·783, 0·525–1·178). Lengths of stay in medium-volume hospitals and high-volume hospitals were 0·915 days (95% CI 0·880–0·951) and 1.047 days (1·007–1·088) days longer, respectively, than in low-volume hospitals. The hospitalization costs per inpatient with AMI in medium-volume hospitals (OR 1·087, 95% CI 1·051–1·125) and high-volume hospitals (1·230, 1·188–1·274) were higher than in low-volume hospitals. InterpretationGiven that in-hospital mortality was lower in medium-volume hospitals than in low-volume and high-volume hospitals, it is important to recognise that pursuit of high patient volumes and volume-based referral may not improve overall outcomes for inpatients with AMI, particularly in countries in which medical resources are strained. FundingNational Natural Science Foundation of China (number 71473099).