Background Coronary heart disease (CHD) mortality rates have halved in recent decades. However, CHD remains the largest cause of death in Scotland generating persistent socioeconomic inequalities. A socioeconomic quantification of the prevention and treatment contributions to these mortality reductions might help inform future health policies.

Methods IMPACTsec, a previously validated policy model, was used to apportion the Scottish CHD mortality decline between 2000 and 2010 to changes in six major CHD risk factors and to 40 treatments in nine patient groups. Analyses were stratified by gender, age and Scottish Index of Multiple Deprivation quintiles. Uncertainties around estimates were explored using probabilistic sensitivity analysis.

Results There were 5770 fewer CHD deaths in 2010 than would have been expected if 2000 mortality rates had persisted unchanged. This reflected an overall 43% fall in CHD mortality rates (from 262 to 148 deaths per 100,000), but with a slower 37% decline amongst the two most deprived quintiles. The IMPACTsec model explained approximately 83% of the CHD mortality fall. Treatments accounted for approximately 44% of the fall. This benefit was fairly evenly distributed across deprivation quintiles. Three treatments contributed over half of these benefits: statins for primary prevention (13%) and medical therapies for stable angina (9%) and secondary prevention following revascularisation or myocardial infarction (11%). Risk factors accounted for approximately 39% of the mortality fall overall, with the largest contribution in the most deprived quintile (44%) and the least in the most affluent quintile (36%). The decline in systolic blood pressure made the biggest contribution (37%), exceeding that of smoking (4%), total cholesterol (9%) and inactivity (2%); the latter three demonstrating socioeconomic gradients. However, increases in diabetes and obesity negated some of these benefits potentially exacerbating mortality by -8% and -4% respectively. The diabetes contribution to the exacerbation of mortality showed strong socioeconomic patterning (-12% for the most deprived quintile compared to -5% for the most affluent).

Conclusion This IMPACTsec analysis suggests that NHS medical treatments have made a large and equitable contribution to the recent decline in Scottish CHD mortality. The substantial contribution that improvements in risk factor profiles made on CHD mortality rates was diminished by adverse trends in obesity and diabetes; the latter having an adverse socioeconomic gradient. Population-wide interventions can be powerful, rapid and equitable. However, more radical policies will be required if the CHD mortality decline is to continue in future decades while reducing inequalities.