Patients seen in independent sector treatment centres (ISTCs) tend to be younger, in better health and from "far more affluent areas" than those seen by NHS hospitals, research suggests.
The research, published in the British Medical Journal, also shows patients undergoing surgery in ISTCs had "slightly better outcomes" than patients treated in NHS centres.
However, the researchers claim such differences are "minor" and "unlikely to be clinically significant".
The researchers, led by Professor Jan van der Meulen at the London School of Hygiene and Tropical Medicine, claims the study proves ISTCs treat patients with a more "favourable mix case profile".
Yet, they also claim the results of their research "lessons concerns that ISTCs are 'cherry picking' the healthiest patients."
"Our findings support the idea that separating elective surgical care from emergency services could improve the quality of care," said the researchers.
Concerns over the quality of care provided by ISTCs and their arguable 'destabilising impact' on wider NHS service provision and surgical training prompted the researchers to compare the characteristics of patients and outcomes after elective surgery in ISTCs with those undertaken by NHS providers.
They studied patients undergoing hip or knee replacement, hernia repair, or surgery for varicose veins in 25 ISTCs and 72 NHS centres.
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