Knee replacement surgery decreases after NHS introduced patient's weight policies

Updated: Jul 1

Weight/body mass index (BMI) policies introduced by NHS commissioning groups in England are associated with a decrease in knee replacement surgery and may be contributing to health inequalities, according to a National Institute for Health and Care Research (NIHR) funded study, led by the University of Bristol.

The findings reported in the paper, ‘What effect have NHS commissioners' policies for body mass index had on access to knee replacement surgery in England?: An interrupted time series analysis from the National Joint Registry’, published in PLoS ONE, suggest the regions that introduced policy changes for access to knee replacement surgery based on a patient's weight/BMI have seen a decline in surgery.

"NHS policy on whether people can immediately access referral for knee replacement surgery if they are overweight or obese varies depending on where you live in England,” explained Dr Joanna McLaughlin, NIHR Doctoral Fellow in the Bristol Medical School: Translational Health Sciences (THS) and lead author of the study. "Our study raises the concern that these policies are linked with worsening health inequalities with fewer NHS operations for the least affluent groups in society when policies are introduced."

Over the last decade rules have been bought in by NHS clinical commissioning groups (CCGs) across England to change the access to hip and knee replacement surgery for patients who have overweight or obesity. However, there is a lot of regional difference, with some regions having no such policy and in the strictest examples patients being denied access to an elective hip or knee replacement operation until their BMI is below a certain threshold.


The aim of the research was to investigate the effect of these commissioning policies on access to elective knee surgery and if there was any evidence of worsening health inequalities through a disproportionate effect on less affluent groups in society.

The research team analysed the rates of knee replacement surgery of 481,555 patients between January 2009 and December 2019 using data from the National Joint Registry and compared regions with and without a BMI policy.


The study found the policies put in place by NHS CCGs to change access to knee replacement based on a patient's weight/BMI are linked with a decrease in surgery and could have led to postcode health inequalities.


The research highlighted that the rules may be worsening health inequalities as policy introduction can be linked to a rise in patients having private surgery and a reduction in the most economically deprived patients receiving surgery at all. Rates of surgery fell in all patient groups, and not just for people with overweight or obesity , who the policy was targeted at.


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.


“Body mass index policy introduction was associated with decreases in the rates of knee replacement surgery across localities that introduced policies. This affected all patient groups, not just obese patients at whom the policies were targeted” the researchers concluded in their paper. “Changes in patient demographics seen after policy introduction suggest these policies may increase health inequalities and further qualitative research is needed to understand their implementation and impact.”


To access this paper, please click here