Title: Investigating the impact of frailty on the risks and benefits of hip and knee replacement surgery
Funder: Department of Health and Social Care

Abstract: Background:Frailty is common in older age and the prevalence is increasing because of the aging population. Joint replacement surgery, typically undertaken to treat osteoarthritis, is one of the most frequently performed operations in older people, however, the impact of frailty on health outcomes following joint replacement surgery is not known. Such data are important and may help inform shared decisions about surgery in this vulnerable group.Aims and objectives:The overall aim is to determine how frailty impacts on the risks and benefits of hip and knee replacement surgery. The objectives are to determine whether: the impact of frailty on short-term term (1 year) mortality risk following total hip/knee replacement is different compared to the impact of frailty on mortality risk over the same period in people who do not have a total hip/knee replacement frailty impacts on the change in hip/knee pain and function following total hip/knee replacement surgery, compared to before surgeryhaving a total hip/knee replacement impacts on the longitudinal change / progression of frailtythe prevalence of frailty in people who have a total hip/knee replacement has changed during the period 2004 to 2017 Methods:Data from the Clinical Practice Research Datalink (CPRD), linked to Hospital Episode Statistics (HES), will be used. Frailty will be defined using the validated electronic Frailty Index (eFI). Cox regression will be used to model mortality risk, and to determine the impact of frailty on mortality, in people who have a total hip/knee replacement compared to propensity score matched participants who do not have a total hip/knee replacement. Linear regression will be used to determine whether frailty impacts on the change in patient-reported joint pain and function (Oxford Hip/Knee Score (OHS/OKS)) 6 months after hip or knee replacement surgery, compared to just before surgery. Multilevel models will be used to analyse prospective change in frailty index in people who have a hip/knee replacement compared to those who do not have surgery. Multivariable Poisson regression models will be used to determine whether the prevalence of frailty in people who have total hip or knee replacement surgery has changed over time.Timelines for delivery: The proposed start date is September 2018 and the project will be completed by September 2021. Work on data preparation and linkage, as well as objective i) will take place in year 1. Work on the OHS/OKS outcomes and longitudinal change in frailty (objectives ii) and iii)) will take place in year 2. In year 3, objective iv) will be completed and also final thesis write up.Anticipated impact and dissemination: The proposed research will help better define the risks and potential benefits of total hip and knee replacement surgery in older people who are frail and therefore may help inform shared decisions about joint replacement surgery. The results of the research will be disseminated through engagement with patient groups, orthopaedic surgeons, and also charities. Results from this research will be presented also at conferences and in scientific journals.

Lay abstract: Background to the research: Frailty is a common and widely recognised health issue in older people. People who are frail are more prone to ill health and may be less able to recover from significant health events including surgery. Hip and knee replacement surgery are among the most frequently performed operations in older people. What we don't know, and what this research will find out, is what the risks and benefits of this type of surgery are in older people who are frail.Aim: To find out how frailty affects the risks and benefits of joint replacement surgery including the risk of death following surgery, as well as changes in pain and the ability to carry out basic daily activities. Also, whether joint replacement surgery may lead to improvement or worsening of frailty.Design and methods used:A database of general practice records for over 11 million patients in the UK will be used for this research. The database includes details about hip and knee replacement surgery. Linking the general practice records to hospital records will will provide information about levels of patient reported pain and the ability to carry out basic daily activities both before and after hip or knee replacement surgery. A new method of identifying people with frailty, using existing health records has been recently been developed and this will be used to identify people who are frail for this study. Statistical models will be used to analyse whether frailty affects the risks and also potential benefits of surgery.Patient and public involvement:This project has been discussed with a group of 11 people who have, or care for someone with, a musculoskeletal condition, including people with osteoarthritis. The group felt that the planned research is important because it will provide useful information about the risks and benefits of hip and knee replacement surgery to both patients who may have been offered surgery and also orthopaedic surgeons who undertake these procedures.Impact and Dissemination:The proposed research will provide information about the risks and potential benefits of hip and knee replacement surgery in older people who are frail. This will improve shared decision making about whether to go ahead with hip or knee replacement surgery. Results from this research will be discussed with patient groups, orthopaedic surgeons, charities, including Age UK and Arthritis Research UK, and the wider public though the media. Results from this research will be presented also at national and international conferences and in scientific journals.

Research activity codes: 6.4 SURGERY
Health categories: MUSCULOSKELETAL