Ninety per cent of hip or knee replacement patients are pre-obese or obese, says new research

May 1, 2019

Nine out of 10 patients having knee or hip replacements are classified as pre obese or obese, according to new Australian research.
The results of a 10 month study into 247 patients undergoing elective surgery for knee and hip replacements at a regional NSW hospital found that while one in ten patients were of normal weight most were either pre-obese with a body mass index (BMI) of 25-29.9 or obese with BMIs of more than 30.

Conjoint Associate Lecturer in Medicine at the University of NSW Dr Vanessa Chen began the study while working as a resident medical officer in regional NSW. She presented the findings at the Australian and New Zealand College of Anaesthetists’ annual scientific meeting in Kuala Lumpur.

Obesity costs the Australian economy $11.8 billion ($5.4 billion in direct health costs and $6.4 billion in indirect costs in 2017/2018) according to a recent report released by the Collective for Action on Obesity.

Dr Chen said the demand for total knee and hip replacements in Australia hospitals is increasing due to rising obesity rates and an ageing population.

“Studies have shown that obesity has a significant impact on health economics due to longer length of stays and increased complications, despite improved surgical and anaesthetic techniques,” she explained.

Of the patients studied 14 per cent were “class 3” obese with BMIs of more than 40 and 20 per cent were “class 2” obese with BMIs of between 35-39.9. The “class 3” patients required longer hospital stays and had higher rates of rehabilitation while “class 2” patients had the most medical emergency response team calls.

Patients with high BMIs were also more likely to need a general anaesthetic rather than a regional or local anaesthetic.

“The implication of excess body weight on future bed allocation and heath care costs was evident in this study,” Dr Chen said.

“There was a greater need for increased post-operative care with obese patients with greater unplanned intensive care unit admissions and medical emergency response team calls. As BMI increased the average length of stay was longer and these patients were more likely to need transfer to a rehabilitation facility despite a longer hospital stay.”

More than 1900 anaesthetists, pain specialists and other medical practitioners have gathered for the ANZCA meeting New worlds come explore at the Kuala Lumpur International Convention Centre. The meeting features dozens of significant research papers, workshops and presentations on clinical and scientific advances.
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