Areas of high deprivation were more likely to report low CHD prevalence despite high mortality rates, researchers reported at the annual scientific meeting of the Society for Academic Primary Care.
The study findings also contradict suggestions that areas of high deprivation would have higher rates of exception reporting than those of low deprivation.
For CHD there was no significant difference between the two groups, with exception reporting averaging 7.5 per cent.
Quality framework data from 8,124 GP practices in England for 2004/5 were analysed, alongside information from the 2001 UK census, CHD mortality data and data on practice characteristics.
Although reported CHD prevalence strongly correlated with mortality rates for PCTs, the more deprived a population, the more likely reported prevalence was to deviate from that modelled.
In the worst PCTs, up to 3,300 expected CHD cases were missing from GP registers.
Lead researcher Dr Tim Doran, from the National Primary Care Research and Development Centre in Manchester, was unwilling to name the PCTs until the finding is clarified.
'Your first suspicion is that people in high deprivation areas are not being registered, but the thing is, in these areas some people are dying quite young.'
Because age at death is used to weight mortality rate calculations, it may be that practices are registering most CHD patients, but because they die young the mortality rate seems especially high, he said.
'It doesn't look like the number of practices missing patients is any greater than the nationwide undercount. If we did screen people for CHD, we would see that undercount come down.'
A Healthcare Commission report showed that up to 140,000 cases of heart failure were missed across England each year. GP electronic record systems and lack of access to diagnosis were cited as potential causes.Comment below and tell us what you think