David Cameron's plans for a 'friends and family test' to assess the care received by patients within the NHS could cost the government £600 million to implement.
The prime minister has said he wants the test to act as a "flashing light" to warn the government if certain elements of the health service are underperforming.
From April, all patients in hospitals in England will be issued with a questionnaire and asked if they would recommend their place of treatment.
The estimated cost of the project has been revealed in the government's impact assessment, which also predicts a maximum financial benefit of just £532 million resulting from it.
Widely criticised by experts and campaign groups, the test has been branded "useless and meaningless".
Following the announcement of the new rating system, the NHS Alliance said there are already structures in place to gather feedback on treatment and warned it is "not the mechanism we need".
"The friends and family test won't add anything new, or tell patients what they want and need to know," it added.
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