Correlates of coronary angiography in patients with stable angina and geographical differences in its utilisation: the ACTION experience.

Background: Utilisation of coronary angiography (CAG) varies between different countries. For patients with stable angina, the present study aimed to assess whether such differences could be explained by differences in patient characteristics, and whether these differences were related to outcome.
Methods: Using data from the ACTION trial, which compared long-acting nifedipine GITS with placebo in 7665 patients with stable angina from 19 countries, we determined by country the ratio of the observed (O) and the expected (E, based on multivariate models) number of patients who had a history of CAG before entry, or underwent CAG during a mean follow-up of 5 years. Similarly, we determined corresponding O/E ratios for the combined occurrence of any death, myocardial infarction (MI) or debilitating stroke (DS) during follow-up.
Results: O/E ratios for a history of CAG before entry ranged from 0.68 [95% confidence interval (CI) 0.60-0.77) for Sweden to 1.43 (95%CI 1.36-1.44) for Belgium, and were significantly correlated (p=0.04) to the corresponding O/E ratios for CAG during follow-up. The combined O/E ratio for CAG either before entry or during follow-up was not correlated (p=0.7) to the O/E for death, MI or DS, which ranged from 0.38 (95%CI undetermined) for Austria to 1.34 (95%CI 0.80-1.89) for France.
Conclusions: The degree to which CAG is utilised in patients with stable angina varies between countries but is not related to the occurrence of death, MI or stroke. This supports the notion that percutaneous coronary intervention does not reduce the risk of events.