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NHS policies on patient's weight and access to hip replacement surgery are inappropriate, study finds

A hip replacement x-ray

A hip replacement x-rayMusculoskeletal Research Unit, University of Bristol

Press release issued: 13 June 2023

Weight and body mass index (BMI) policies introduced by NHS commissioning groups in England are inappropriate and worsening health inequalities, according to a new study published in BMC Medicine today [13 June] that analysed nearly 490,000 hip surgeries. With one in ten people likely to need a joint replacement in their lifetime, many thousands of patients are directly affected by these policies.

Rules implemented by NHS clinical commissioning groups (CCGs) across England to change the access to hip and knee replacement surgery for patients who are overweight or obese have been in effect for over ten years. However, regional differences in this BMI mandate means some areas have no such policy while in other areas, patients are denied access to a hip replacement operation until their BMI is below a certain threshold or until they have waited extra time.

Researchers from the University of Bristol sought to assess the impact of these BMI policies on access to hip replacement surgery in England, and if there was any evidence of worsening health inequalities.  The study was funded by the National Institute for Health and Care Research (NIHR).

The team analysed the rates of hip replacement surgery of 480,364 patients between January 2009 and December 2019 using data from the National Joint Registry (NJR). They then compared regions with and without a BMI policy.

Their results found policies to change access to hip replacement based on a patient's weight/BMI were linked with a decrease in surgery rates, particularly in those living in deprived areas, whereas rates rose in localities with no policy. Regions with strict BMI threshold policies were associated with the sharpest fall in rates (trend change of -1.39 operations per 100,000 population aged 40+ per quarter-year).

Some BMI policies add extra waiting time before surgery for hip replacement patients with a high BMI. The professional support available to help patients reduce their weight in this time is very variable. There was an association with worsening symptom scores and worsening obesity with the introduction of these extra waiting time rules, showing the policies may in fact be counterproductive.

Dr Joanna McLaughlin, NIHR Doctoral Research Fellow in the Bristol Medical School: Translational Health Sciences (THS) and lead author of the study, said: “NHS policy on whether people can immediately access referral for hip replacement surgery if they are overweight or obese varies depends on where you live in England.

"NICE guidance on arthritis was updated in October 2022, and it clearly states that BMI should not be used to exclude people from referral to surgery, but restrictive policies are still in use in some regions.

"Both this current study, and our study on knee replacements published last June, show these policies have concerning associations with a sharp drop in the rate of joint replacements, worsening symptom scores, and worsening health inequalities."

The research team urge commissioners and policy decision-makers to reconsider restrictive policies that affect access to elective surgery as a matter of urgency. The researchers also suggest that the recent formation of Integrated Care Systems from existing CCG groups is an important opportunity for positive changes to policy position and there are encouraging signs that some regions are already taking these policy change steps.


'What effect have commissioner'’ policies for body mass index had on hip replacement surgery?: An interrupted time series analysis from the National Joint Registry for England' by Joanna McLaughlin et al. in BMC Medicine [open access]

Further information

About the National Institute for Health and Care Research (NIHR)
The mission of the National Institute for Health and Care Research (NIHR) is to improve the health and wealth of the nation through research. We do this by:

  • Funding high quality, timely research that benefits the NHS, public health and social care;
  • Investing in world-class expertise, facilities and a skilled delivery workforce to translate discoveries into improved treatments and services;
  • Partnering with patients, service users, carers and communities, improving the relevance, quality and impact of our research;
  • Attracting, training and supporting the best researchers to tackle complex health and social care challenges;
  • Collaborating with other public funders, charities and industry to help shape a cohesive and globally competitive research system;
  • Funding applied global health research and training to meet the needs of the poorest people in low and middle income countries.

NIHR is funded by the Department of Health and Social Care. Its work in low and middle income countries is principally funded through UK Aid from the UK government.

The NIHR is the research partner of the NHS, public health and social care.

About the National Joint Registry (NJR) 
The NJR, which covers England, Wales, Northern Ireland, the Isle of Man, and Guernsey, collects information on hip, knee, ankle, elbow and shoulder joint replacement surgery, across both the NHS and independent sector. Data collection began in April 2003 and data submission for NHS organisations was made mandatory from April 2011.

Now with around 3.7 million procedure records, the NJR is the largest orthopaedic registry in the world with an international reputation. Recognised as a ‘global exemplar’ of an implantable medical devices registry, the NJR monitors the performance and effectiveness of joint replacement implants in different types of joint replacement surgery, in order to provide an early warning of issues relating to patient safety and improve clinical standards; thus benefiting patients, clinicians and the orthopaedic sector as a whole. 

For more information about the NJR see:

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