Data analysis of knee surgery finds social factors have only a small part to play in outcomes

An analysis of the UK National Joint Registry data set has found that social factors such as age, gender, deprivation and living arrangements have a very small influence on outcomes of knee replacement surgery.

The research, from a team at the University of Bristol part-funded by NIHR CLAHRC West, found that younger and poorer patients were likely to have slightly less improvement after the operation compared to older and richer patients. Women and men had a very similar amount of improvement, but women tended to start off with worse symptoms before the operation. Overall the effect of these social factors had only a very small effect on outcomes.

The success of a medical treatment is sometimes related to the patient’s gender, age or prosperity. It is important to investigate this to try to reduce inequalities in outcomes.

Replacement knee surgery is a very common and effective procedure in the UK, but there is little information about whether everyone can expect the same good outcome regardless of their circumstances.

The UK National Joint Registry data set collects information on most knee surgeries carried out in England. The Department of Health and Social Care also collects information from patients to assess the success of various operations. People are sent a survey about their knee pain and function, both before and six months after their operation to measure how much they have improved. Information about their age, gender, whether they live alone and the area they live in is also collected. The research team combined all this information to analyse how much these social factors are related to knee symptoms and the success of the operation.

Hannah Edwards, who led the research, said:

“It’s reassuring that there’s very little social inequality in the outcomes of replacement knee surgery, especially as it’s such a common operation. But the fact that there were differences in knee symptoms before the operation suggests that there could be inequality in the sorts of people who go for the operation, or when they get it. Our research also raises the question of whether there is inequality with who experiences complications, such as infections, after surgery. We’ll be doing a follow up project to explore this.”