Analysis of quality score data from Scotland, Wales and Northern Ireland for 2006/7 confirmed fears that the mental health targets would prove the most difficult.
In Wales, only 73.9 per cent of depression indicators were met. For mental health, which includes patients with schizophrenia, bipolar disorder and other psychoses, just 86.7 per cent of targets were achieved.
Scotland fared slightly better, hitting 84.6 per cent of depression and 90.8 per cent of mental health targets.
Northern Ireland did best on these clinical indicators, but still only achieved 88.1 per cent of depression targets and 94.6 per cent of those for mental health.
GPC Wales chairman Dr David Bailey said: 'The screening can be difficult because patients can look askance when you ask these questions and there are concerns about the doctor-patient relationship.'
GPC Scotland chairman Dr Dean Marshall said: 'There have been issues with some of the indicators across Scotland, notably for mental health and depression and there is no doubt that that needs to be developed further.'
Nevertheless, these domains should remain to ensure a reward for GPs 'who make a difference in a very difficult but tremendously important area of general practice', added Dr Marshall.
Previous complaints about the mental health domains included that of GPC member Dr Trefor Roscoe, who said that their complexity led GPs to stop trying to achieve targets.
A report submitted to the GPC last year by Wiltshire GP Dr Gavin Jamie highlighted Read code problems.
RCGP spokeswoman Dr Sarah Jarvis said that mental health patients were looked after by both primary and secondary care, which meant that some targets were achieved, but not within the GP practice.
'I think recording is a major issue here,' she said.
In contrast, domains such as chronic kidney disease (CKD) are largely cared for in primary care, explaining good scores all round for these targets, added Dr Jarvis.
Scotland met 99.8 per cent of CKD indicators, Wales 98.1 per cent and Northern Ireland 99.2 per cent.
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