Medical evidence used to decide claimants' eligibility for state benefits is frequently ‘seriously inaccurate', the Citizens' Advice Bureau (CAB) has revealed.
It urged the government to take action to address the problems immediately and warned there could be severe consequences when the process is used to administrate the Universal Credit.
According to research conducted by the CAB, over two thirds of medical assessments submitted for Employment and Support Allowance (ESA) contain enough inaccuracy to have a detrimental effect on the awarding of benefits.
The findings heaped more pressure on the government following yesterday's rejection of three parts of its Welfare Reform Bill by the House of Lords.
As part of the ESA process, claimants must undergo a face-to-face Work Capability Assessment (WCA) conducted by Atos Healthcare to determine what they are capable of doing.
The report is then passed to decision makers at the Department for Work and Pensions (DWP) who use it to decide claimants' eligibility for benefits.
CAB said it has been monitoring the application of ESA since its introduction and the organisation has become increasingly concerned about the WCA process.
It analysed 37 full medical reports supplied by clients and found 16 (43%) contained a serious level of inaccuracy, 10 (27%) a medium level of inaccuracy which would be enough to have a detrimental effect on a subsequent award of Disability Living Allowance (DLA), while only 11 (30%) had a low (or no) level of inaccuracy.
"Our analysis indicates that the level of accuracy in reports is worryingly low," the CAB report said.
"This is true even where ESA has been awarded.
"This report calls on the DWP to undertake, with some urgency, regular, independent monitoring of the accuracy of WCA reports, to ensure that people who are too ill or disabled to work, either in the short- or long-term, are properly supported by the benefit system," it added.
The body explained that the substantial problems with the process were being seen by many of its staff and as a result many people were losing out on benefits they should otherwise be entitled to.
It also noted that other criticism of Atos Healthcare and WCAs had been made and warned about potential impacts should it be used as the gateway test for disability benefit eligibility when the Universal Credit is introduced.
"CAB advisers tell us that inaccurate medical assessment reports are creating huge difficulties for their clients as well as potentially undermining the government's welfare reform programme," it said.
"People with serious illnesses and disabilities, who could not reasonably be expected to seek work, are found fit for work.
"Many others are too ill to sign on for jobseekers' allowance so are left with no money to live on and are unable to seek work.
"In the future, the content of the assessment report, and the awarding of ESA, will become ever more significant," it added.
