Social class inequalities in the decline of coronary heart disease among New Zealand men, 1975-1977 to 1985-1987.

Coronary heart disease (CHD) is regarded as a disease of developed 'western' societies. Within developed societies, however, CHD is typically a disease of the less affluent socioeconomic classes. This has not always been the case. Forty years ago. CHD was reported to be more common among the upper social classes. In New Zealand, as in other developed countries, this original trend across social classes was reversed during the past 40 years. In 1975-1977, a gradient across social class was observed for both CHD and cerebrovascular disease mortality, with the lowest social classes experiencing the highest mortality. This study has now been repeated for the period 1985-1987. Employed males aged 15-64 years were categorized by the Elley-Irving scale into six social classes. The overall age-standardized mortality rate from CHD declined over the ten-year period, from 163.0 to 121.7 per 100,000 person-years. Over the same period, however, the social class gradient for coronary mortality actually increased. The overall age-standardized mortality rate from cerebrovascular disease also declined over the ten-year period, from 25.9 to 17.7 per 100,000 person-years. A social class gradient for cerebrovascular mortality was present in both periods. In contrast to coronary mortality, however, the social class gradient diminished slightly over the ten-year period.