The influence of hospital-level variables on hip fracture outcomes

Aims: To determine the impact of hospital-level service characteristics on hip fracture outcomes and quality of care processes measures. Materials & Methods: Retrospective analysis of publicly available audit data obtained from the National Hip Fracture Database (NHFD) 2018 benchmark summary and Facilities Survey. Data extraction was performed using a dedicated proforma to identify relevant hospital-level care process and outcome variables for inclusion. The primary outcome measure was adjusted 30-day mortality rate. A random forest based multivariate imputation by chained equation (MICE) algorithm was utilised for missing value imputation. Univariable analysis for each hospital level factor was performed using a combination of Tobit regression, Siegal non-parametric linear regression and Mann-Whitney U analyses, dependent on the data type. In all analyses p<0.05 denoted statistical significance. Results: Analyses included 176 hospitals, with a median of 366 hip fracture cases per year. Aggregated data from 66,578 patients were included. The only identified hospital-level variable associated with the primary outcome of 30-day mortality was hip fracture trial involvement (Mann Whitney U test - No trial involvement: median 6.3%, trial involvement: median 5.7%, p-value = 0.0392). Significant key associations were also identified between: prompt surgery and presence of dedicated hip fracture sessions; reduced acute length of stay and both higher number of hip fracture cases per year and more dedicated hip fracture operating lists; Best Practice Tariff attainment and greater number of hip fracture cases per year, more dedicated hip fracture operating lists, presence of a dedicated hip fracture ward and hip fracture trial involvement. Conclusions: Exploratory analyses have identified that improved outcomes in hip fracture may be associated with hospital-level service characteristics such as hip fracture research trial involvement, larger hip fracture volumes, and the use of theatre lists dedicated to hip fracture surgery. Further research utilising patient level data is warranted to collaborate these findings.