Ischaemic heart disease mortality among men in Norway: reversal of urban-rural difference between 1966 and 1989.

OBJECTIVE This study aimed to examine regional urban-rural differences in mortality from ischaemic heart disease, including sudden death of unknown cause (IHD/SUD) in Norway from 1966-89, for men and women aged 30-69 years. DESIGN Analysis was based on vital statistics. Regional mortality rates were obtained by aggregating the 443 municipalities in Norway into urban, rural, and intermediate municipalities. SETTINGS AND SUBJECTS Norway. RESULTS In 1966-70 the age adjusted IHD/SUD mortality in the age group 30-69 years was higher in urban than in rural areas; for men by 31% (95% CI 27%, 36%) and for women by 28% (95% CI 19%, 36%). In 1986-89 the IHD/SUD mortality for men showed a reversed urban-rural gradient: it was 8% (95% CI 2%, 13%) higher in rural than in urban areas. The mortality rates for women were equal for both these aggregates. For men the results indicate that IHD/SUD mortality peaked first in urban municipalities and then, but at a lower level, in rural areas. For women there was a substantial decline in IHD/SUD mortality between 1966 and 1989, but an actual peak could not be demonstrated in any of the three aggregates during the period. The decline in IHD/SUD mortality among women was steepest in urban municipalities and least noticeable in rural municipalities, but the decline tapered off towards the end of the study period. CONCLUSION The results confirm a phase-shifted peak in IHD/SUD mortality, which began in towns and ended in rural areas, and provides clues to the main underlying factors in the IHD epidemic at the population level.