Explaining differences in English hospital death rates using routinely collected data

Objectives To ascertain hospital inpatient mortality in England and to dete rmine which factors best explain variation in standardised hospital death r atios. Design Weighted linear regression analysis of routinely collected data over four years, with hospital standardised mortality ratios as the dependent v ariable. Setting England. Subjects Eight million discharges from NHS hospitals when the primary diagn osis was one of the diagnoses accounting for 80% of inpatient deaths. Main outcome measures Hospital standardised mortality ratios and predictors of variations in these ratios. Results The four year crude death rates varied across hospitals from 3.4% t o 13.6% (average for England 8.5%), and standardised hospital mortality rat ios ranged from 53 to 137 (average for England 100). The percentage of case s that were emergency admissions (60% of total hospital admissions) was the best predictor of this variation in mortality, with the ratio of hospital doctors to beds and general practitioners to head of population the next be st predictors. When analyses were restricted to emergency admissions (which covered 93% of all patient deaths analysed) number of doctors per bed was the best predictor. Conclusion Analysis of hospital episode statistics reveals wide variation i n standardised hospital mortality ratios in England. The percentage of tota l admissions classified as emergencies is the most powerful predictor of va riation in mortality. The ratios of doctors to head of population served, b oth in hospital and in general practice, seem to be critical determinants o f standardised hospital death rates; the higher these ratios, the lower the death rates in both cases.