Up to a fifth of practices may have submitted inaccurate QOF data because of a bug in INPS' Vision computer system.
While the error is unlikely to cost practices any money, those affected have had to complete an upgrade process, and may have to apply to their primary care organisation (PCO) to adjust their QOF claim.
INPS first became aware of the situation after practices complained of problems with the figures reported to the Quality Management and Analysis System (QMAS) on 31 March.
After a day investigating the problem, the company wrote to users saying that 'it is likely that all INPS sites will be affected by this, and the data on any practice's monthly submission could be incorrect'. It added inaccuracies depended on practice size, turnover and demographics.
The problem is caused by an error in the program, which accidentally calculates figures using next year's 'reference date' of 1 April 2010. This means that some procedures that should affect a practice's QOF entitlement are being excluded.
Errors are possible in any data where patients are registered in a set time frame before a reference date, or where their age is calculated in reference to that date. Affected clinical areas include smears and mental health.
The company issued a fix on 9 April, enabling practices to recalculate their QOF score.
Dr Grant Ingrams, co-chairman of the joint GPC/RCGP committee on IT and a Vision user, described the situation as 'a bit of a cock-up'.
'It's frustrating. By now we'd normally know where we stand, and we don't.' He added that the fix had been 'difficult to follow', and had required repeated calls to the INPS helpline.
The situation is expected to be resolved next week, making it unlikely to affect practice income.
The National Vision User Group has advised practices to compare their figures before and after the fix, before deciding to apply to a PCO to adjust their QOF claim.
Around 20 per cent of UK practices use Vision.
INPS declined to comment.
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