Referrals for coronary angiography in a high risk population

To examine variations in referral for coronary angiography within Northern Ireland and relate these to local death rates from coronary artery disease (ICD rubrics 410-414).

A descriptive retrospective analysis of aggregate hospital activity data for 1979-88 and corresponding mortality rates in the local population.

Two regional referral hospitals and 26 local district council areas.

5173 patients aged 35-74 years with an underlying diagnosis of ischaemic heart disease, whose records contained complete information on their age, sex, and home address.

Age-standardised angiography rates and corresponding standardised death rates derived from the registrar general's reports.

Among the 26 constituent district council areas there was significant heterogeneity in the angiography rates, ranging from 62 to 335/100,000 in men and from 7 to 62/100,000 in women (likelihood ratio statistic 856 and 359 respectively). There was no significant association between these angiography rates and the local death rates from ischaemic heart disease.

The results suggest a non-uniform threshold for referral for angiography.

Clinicians need to examine the appropriate indications for referral for invasive investigation.