Association between off-hours admission with acute myocardial infarction and in-hospital mortality

Abstract

Abstract Background The effect of time of admission on clinical outcomes in patients with acute myocardial infarction (AMI) is still a matter of debate. Purpose To investigate the association between off-hours admission and in-hospital mortality in patients with ST-elevation myocardial infarction (STEMI) and non-STEMI (NSTEMI). Methods We used a two-stage, random sampling method to create a nationally representative sample of patients with AMI in 167 Chinese hospitals in four years (2001, 2006, 2011, and 2015). Off-hours were defined as 20:00–07:59 and on-hours as 08:00–19:59. We used hierarchical logistic regression model to examine whether off-hour admissions were associated with in-hospital mortality and 7-day mortality. Inverse-probability weighting propensity score analysis was also conducted to assess the robustness of the results. Results We identified 25654 patients admitted with AMI (median age 67.0 years; 31.6% women), of whom 20133 (78.5%) were diagnosed as STEMI and 5521 (21.5%) as NSTEMI. There were 5368 (26.7%) admissions for STEMI, and 1356 (24.6%) for NSTEMI occurring during off-hours, respectively. After adjusting for case mix, year of admission, comorbidities, clinical presentation, and in-hospital treatments, a significant association was observed between off-hours admissions and in-hospital mortality among the patients with STEMI (adjusted OR 1.14; 95% CI 1.01 to 1.28). The magnitude of the association became greater in the secondary analysis with 7-day mortality as the outcome (adjusted OR 1.16; 95% CI 1.02 to 1.31). But among patients with NSTEMI, no significant association was observed for in-hospital and 7-day mortality. Propensity score analysis showed similar results to hierarchical logistic model for both outcomes in patients with STEMI and NSTEMI. Conclusion Off-hours admission with STEMI is associated with higher in-hospital mortality. Reducing the disparity of care of STEMI by the time of admission represents a potential opportunity for quality improvement in China. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): National Key Research and Development Program (2017YFC1310803, 2017YFC1310801) from the Ministry of Science and Technology of China