Patients undergoing shoulder arthroplasty do better when operated on by surgeons who average more than 10 such operations per year, according to a new study led by the University of Oxford. The results mirror previous findings for hip and knee replacement surgery.
The findings, published in the BMJ, "should help guide future resource planning in this area", the researchers said. They noted that shoulder replacements were becoming increasingly common, with more than 8000 carried out in the UK annually. While previous studies had shown that hip and knee replacement surgery had better outcomes when performed by 'high volume' surgeons, the evidence for other types of joint replacement surgery was more limited.
To fill this knowledge gap, they used statistical models to investigate the effect of annual surgeon volume on outcomes after non-urgent (elective) shoulder replacement surgery, linking data from the National Joint Registry to Hospital Episode Statistics in England.
The study sample included 39,281 elective shoulder replacements performed by 638 consultant surgeons at 416 public and private surgical units between 2012 and 2020. All participants were aged 18 or over and were receiving shoulder arthroplasty for the first time.
Safer Volume Threshold: 10.4 Procedures Annually
After adjusting for a range of potentially confounding factors, the researchers identified a mean annual volume threshold of 10.4 procedures per year, above which there was a 45% overall lower risk of revision surgery than for patients treated by surgeons who performed fewer than this. Below this threshold, the risk of revision surgery was as much as twice that of surgeons with the lowest risk (hazard ratio 1.94, 95% CI 1.27 to 2.97).
Patients of surgeons who had a greater mean annual surgical volume were also at significantly lower risk (by 53%) of re-operations within 12 months, had fewer serious adverse events (-40% at 30 days and -37% at 90 days), and had a 62% reduction in the risk of a prolonged hospital stay (more than 3 nights). No minimum case volume threshold was identified for these outcomes.
Annual variation in surgeon volume was not associated with any of the outcomes assessed, which the authors said suggested that a surgeon’s average annual volume of procedures over the course of their career was more important for better patient outcomes than variation in annual procedure volumes.
The researchers concluded: "A near linear association exists between surgeon volume and adverse events after shoulder replacement surgery, with patients receiving shoulder replacements by higher volume surgeons showing a reduced risk of reoperation, fewer serious adverse events, and shorter hospital stay."
Evidence Should Inform Future Planning
They added: "Improving outcomes and reducing complications after joint replacement surgery is of clear benefit to patients and their families.
"This study offers evidence for local hospitals and national healthcare services that informs workforce and resource planning to ensure the best outcomes for patients undergoing shoulder replacement surgery."
In a linked editorial, Marta Karbowiak of Portsmouth Hospitals NHS Trust, and Nashat Siddiqui of Kingston Hospital NHS Foundation Trust, said that the study was "a useful addition to current knowledge of the association between surgeon volume and patient outcomes". However, they pointed out: "Registry data need to be interpreted carefully at surgeon, hospital, and national level, as currently available outcome measures may not tell the whole story."
Patient characteristics and complexity vary considerably, particularly in shoulder arthroplasty, which is generally considered a technically more difficult procedure and arguably has greater potential for technical errors and complications than hip or knee replacement surgery, they said. Data available often report only revision rates or major adverse outcomes, and may not reliably capture patient reported outcomes, such as quality of life, or functional and wellbeing measures.
National Institute for Health and Care Research (NIHR) and the NIHR Oxford Biomedical Research Centre. EMV is a NIHR doctoral fellowship award holder. RPV is co-applicant on research grants to the NIHR to the University of Oxford. MRW is principal investigator or co-applicant on research grants to NIHR to the University of Bristol. JLR holds an NIHR senior investigator award and is president of the British Elbow and Shoulder Society. MRW, AS, and JLR hold a contract with the National Joint Registry.