An ecological comparison of hospital-level antibiotic use and mortality in 36,124,372 acute/general medicine inpatients in England

<jats:p>Objectives: To determine the extent to which variation in hospital antibiotic prescribing is associated with mortality risk in acute/general medicine inpatients. Design: Ecological analysis, using electronic health records from Hospital Episode Statistics (HES) and antibiotic data from IQVIA. Setting: 135 acute National Health Service (NHS) hospital Trusts in England. Participants: 36,124,372 acute/general medicine inpatients (≥16 years old at admission) admitted between 01/April/2010-31/March/2017 (median age 66 years, 50.4% female, 83.8% white ethnicity). Main outcome measures: Random-effects meta-regression was used to investigate whether heterogeneity in the adjusted probability of death within 30-days of admission was associated with hospital-level antibiotic use, measured in defined-daily-doses (DDD)/1,000 bed-days. Models also considered DDDs/1,000 admissions and DDDs for selected antibiotics, including narrow-spectrum/broad-spectrum, inpatient/outpatient, parenteral/oral, piperacillin-tazobactam and meropenem, and Public Health England interpretations of World Health Organization Access, Watch, and Reserve antibiotics. Secondary analyses examined 14-day mortality and non-elective re-admission to hospital within 30-days of discharge. Results: There was a 15-fold variation in hospital-level DDDs/1,000 bed-days and comparable or greater variation in broad-spectrum, parenteral, and Reserve antibiotic use. After adjusting for a wide range of admission factors to reflect varying case-mix across hospitals, the adjusted probability of 30-day mortality changed by -0.010% (95% CI: -0.064 to +0.044) for each increase in hospital-level antibiotic use of 500 DDDs/1,000 bed-days. Analyses focusing on other metrics of antibiotic use, sub-populations, and 14-day mortality also showed no consistent association with the adjusted probability of death. Discussion: We find no evidence that the wide variation in antibiotic use across NHS hospitals is associated with case-mix adjusted mortality risk in acute/general medicine inpatients. Our results indicate that hospital antibiotic use in the acute/general medicine population could be safely cut by up to one-third, greatly exceeding the 1% year-on-year reductions required of NHS hospitals.</jats:p>