Geographical variation in outcomes of primary hip replacement: study from "The National Joint Registry of England and Wales"

Objective The aim of this study was to explore variation in patients’ outcomes for primary hip replacement surgery across Clinical Commissioning Groups (CCGs), and to identify whether patient, surgical and hospital factors can explain why such variation exists. Material and Methods The National Joint Registry was used, which incorporates data on hip replacement surgeries. Primary operations were linked with Hospital Episode Statistics data which contains records of all inpatient episodes undertaken in NHS hospitals, and Patient Reported Outcome Measures (PROMs). Primary hip replacement in people aged 18 years or over between 2014 and 2016 were identified. Multilevel regression models were generated for the following outcomes: length of stay (LOS), bed costs, change in Oxford hip score (OHS) 6-months after surgery, and complication by 6 months. Models included a wide range of patient, surgical and hospital organisation factors. Geographical Information Systems are used to display maps describing adjusted estimates of variation in outcomes across NHS CCG areas. Results 173,107 primary hip replacements were identified within 207 CCG areas. 60% of patients were women, with an average age 69.3 years (SD ±10.7 years). Whilst we identified a number of factors that predicted outcomes of surgery (e.g. age, gender, co-morbidity, deprivation, baseline function, surgical volume, numbers of orthopaedic surgeons, beds, operating theatres), these factors did not explain the observed geographical variations in outcomes of surgery across CCGs. The predicted mean length of stay at hospital oscillated from 2.7 to 6.1 days, bed-day cost £4727 to £8800, absolute predicted change in OHS 18.8 to 24.6, predicted 6-month complication rate from 3.0% to 5.4% (Figure). Conclusions We have identified potentially unwarranted variations in patient outcomes of hip replacement surgery. This variation cannot be explained by differences in patients case mix, surgical factors, or hospital organisational factors. This information is informative to patients in making a decision in where they have their surgery, and to commissioners in monitoring variations in outcomes of surgery