Title: Survival and Recovery After Hip Fracture Surgery by Timing of Mobilisation: Secondary analysis of the National Hip Fracture Database
Funder: Department of Health and Social Care

Abstract: Background Annually UK hospitals admit 75,000 men and women over the age of 60 years with hip fracture. Even with treatment, 30% of patients die within a year. Among survivors, 25% never walk again, and 22% transition from independent living to long-term care. Early mobilisation after hip fracture surgery is defined as getting out of bed within 36-hours of the procedure. Proponents of early mobilisation argue that longer waits affect recovery through rapid loss of muscle strength induced by bedrest. The average patient with hip fracture is 83 years old, frail, and has at least one comorbidity. For these patients, maintaining the strength required to get out of bed could mean the difference between returning home and admission to long-term care. Further, longer waits may lead to potentially-fatal complications such as pulmonary embolism, or pneumonia. Concern about the potential harm from delays led National Health Service Improvement to add early mobilisation to the Fragility Hip Fracture Best Practice Tariff in 2017. To comply with the Tariff, hospitals across the UK will start prioritizing mobilisation after hip fracture surgery over other surgeries, such as femoral shaft fractures. Yet it remains unclear whether early mobilisation yields a survival or recovery benefit for these patients. One obstacle in studying the effects of delayed mobilisation has been a lack of information about rehabilitation and recovery in hospitalisation records. Therefore, we propose to examine available records for 225,000 patients from the National Hip Fracture Database (NHFD). This registry assembles data on the timing of mobilisation, and functional status before and 30-days post-fracture for patients hospitalised with hip fracture in England, Wales and Northern Ireland. Aims and objectives We aim to conduct a secondary analysis of the NHFD to determine whether early mobilisation is associated with survival and recovery after hip fracture surgery. More specifically, our objectives are to determine: whether mobilisation within 36-hours of surgery is associated with the cumulative incidence of survival on discharge; whether mobilisation within 36-hours of surgery is associated with survival and recovery at 30-days post-fracture; and whether these putative associations vary across subgroups defined by characteristics of patients, their injury and care delivery. Methods Study cohort All patients 60 years of age or older who underwent hip fracture surgery in England, Wales, or Northern Ireland between 2014 and 2016 (n = 225,000). Data source We will retrieve data on the characteristics of patients, their injury, and care delivery, survival on discharge, and survival and recovery at 30-days by linking the NHFD to the Hospital Episode Statistics, the Patient Episode Database for Wales and the National Statistics Death Register. Statistical analysis We will calculate the cumulative incidence of live discharge as a function of postoperative day, with in-hospital death being a competing event, by timing of mobilisation. We will use regression with weighting by inverse propensity score to compare the ratio of live discharge, survival and recovery at 30-days, by timing of mobilisation. We will adjust our analyses for factors associated with poor survival and recovery after hip fracture surgery. We will conduct subgroup and interaction analyses to determine whether there is variation in the effect of mobilisation timing across patient subgroups. Expected output This study will determine whether early mobilisation is associated with survival and recovery after hip fracture. The study will also identify who may benefit most from early mobilisation, as optimal timing may vary across patient subgroups. We will publish results in peer reviewed journals and present findings locally, nationally and internationally. In addition, this study will also provide preliminary estimates of an effect size should a subsequent trial be justified to resolve uncertainty revealed by the study.

Lay abstract: In 2016, UK health officials instructed that hospital staff must help patients get out of bed (mobilise) within 36 hours of surgery to fix their broken hip. We spoke with several patients and their caregivers who said they would like to know why they have to get out of bed so quickly. For those who did not get out of bed within 36 hours, they said would like to know whether waiting longer was harmful. Our study asks whether waiting more than 36 hours to get out of bed is harmful for people who had surgery for a broken hip. We also want to know if waiting is harmful for some patients but not harmful for others. If this is the case then hospitals can identify patients who should get out of bed within 36 hours of surgery, and those who can wait longer. We will look at records for people older than 65 years of age who had surgery to fix a broken hip between 2014 and 2016 in the UK National Hip Fracture Database. We will find out whether they were sick before they broke their hip and how badly it was injured. We will see how often people get sick while waiting to get out of bed. We will also find out whether people who wait are less likely to get their walking back, or to die after getting out of bed. We will meet with patients and their caregivers to help us to interpret the findings. We will then share what we learn about who is at risk from waiting with people who make decisions about how UK hospital are run, people who have broken a hip, and caregivers. We will also present our findings at national and international meetings of researchers and hospital staff.

Research activity codes: 8.1 ORGANISATION AND DELIVERY OF SERVICES;2.4 SURVEILLANCE AND DISTRIBUTION
Health categories: INJURIES AND ACCIDENTS