The North-South gradient in myocardial infarction and coronary death rates in various western European regions has been described by the WHO MONICA Project over the last decade. The results of the 5-year follow-up of the Prospective Epidemiological Study of Myocardial Infarction (PRIME) Study reported here give the opportunity of extending the comparison to the incidence of angina pectoris in men aged 50-59 living in four regions (Belfast, Lille, Strasbourg, Toulouse) which were covered by the MONICA Project.
The PRIME Study is a multicentre cohort study with a common protocol and centralized event analysis. It included 10 600 men, of whom 9758 (7359 in France and 2399 in Belfast) were free of coronary disease at entry with 842 (496 in France and 346 in Belfast) having pre-existing coronary disease.
In France, subjects free of coronary heart disease at baseline developed 106 cases of myocardial infarction or coronary death (2.93/1000 subjects per year) and 94 cases of angina pectoris (2.61/1000). In Belfast, 61 developed myocardial infarction or coronary death (5.24/1000) and 60 angina pectoris (5.39/1000). Hazard rate ratios for Belfast in comparison to France were respectively 1.79 (95% CI : 1.30-2.47) and 2.07 (1.49-2.86) for each class of clinical complication.
Rate ratios for angina pectoris incidence between Northern Ireland and France in the PRIME Study are comparable to those for myocardial infarction or coronary death reported by the WHO MONICA Project and suggest that the North-South gradient in Europe applies to different manifestations of coronary disease.