Does acute myocardial infarction kill more people on weekends? Analysis of in-hospital mortality rates for weekend admissions in Portugal.

Objectives To investigate a possible weekend effect in the in-hospital mortality rate for acute myocardial infarction in Portugal, and whether the delay in invasive intervention contributes to this effect. Methods Data from the National 2011-2015 Diagnostic-Related-Group databases were analysed. The focus was on adult patients admitted via the emergency department and with the primary diagnosis of acute myocardial infarction. Patients were grouped according to ST-elevation myocardial infarction and non-ST-elevation myocardial infarction episodes. We employed multivariable logistic regressions to determine the association between weekend admission and in-hospital mortality, controlling for episode complexity (through a severity index and acute comorbidities), demographic characteristics and hospital identifications. The association between the probability of a prompt surgery (within one day) and the day of admission was investigated to explore the possible delay of care delivery for patients admitted during weekends. Results Our results indicate that in-hospital mortality rates were not significantly higher for weekend admissions than for weekday admissions in both ST-elevation myocardial infarction (STEMI) and non-STEMI episodes. This result is robust to the inclusion of a number of potential confounding mechanisms. Patients admitted on weekends had lower probabilities of undergoing invasive cardiac surgery within the day after admission, but delay in care delivery during the weekend was not associated with worse outcomes in terms of in-hospital mortality. Conclusions There is no evidence for the existence of a weekend effect due to admission for acute myocardial infarction in Portugal, in both STEMI and non-STEMI episodes.