How do time trends in inhospital mortality compare? A retrospective study of England and Scotland over 17 years using administrative data

OBJECTIVES To examine the trends in inhospital mortality for England and Scotland over a 17-year period to determine whether and if so to what extent the time trends differ after controlling for differences in the patients treated. DESIGN Analysis of retrospective administrative hospital data using descriptive aggregate statistics of trends in inhospital mortality and estimates of a logistic regression model of individual patient-level inhospital mortality accounting for patient characteristics, case-mix, and country-specific and year-specific intercepts. SETTING Secondary care across all hospitals in England and Scotland from 1997 to 2013. POPULATION Over 190 million inpatient admissions, either electively or emergency, in England or Scotland from 1997 to 2013. DATA Hospital Episode Statistics for England and the Scottish Morbidity Record 01 for Scotland. MAIN OUTCOME MEASURES Separately for two admission pathways (elective and emergency), we examine aggregate time trends of the proportion of patients who die in hospital and a binary variable indicating whether an individual patient died in hospital or survived, and how that indicator is influenced by the patient's characteristics, the year and the country (England or Scotland) in which they were admitted. RESULTS Inhospital mortality has declined in both countries over the period studied, for both elective and emergency admissions, but has declined more in England than Scotland. The difference in trend reduction is greater for elective admissions. These differences persist after controlling for patient characteristics and case-mix. CONCLUSIONS Comparing data at country level suggests questions about the roles performed by or functioning of their healthcare systems. We found substantial differences between Scotland and England in regard to the trend reductions in inhospital mortality. Hospital resources are therefore being deployed increasingly differently over time in these two countries for reasons that have yet to be explained.