Background Between 2000 and 2010, coronary heart disease (CHD) mortality rates in Scotland fell by over one third. Important contributions came from reductions in blood pressure and serum cholesterol (primary prevention). However, the relative contributions from preventive medications (anti-hypertensives and statins) in individuals and from population-wide dietary changes remain unclear. We therefore examined the impact of differential effects on health inequalities.

Methods We used the previously validated IMPACTsec model to estimate the contributions of population-level risk factor changes and treatment changes to the CHD mortality decline in Scotland between 2000 and 2010 for adults aged over 25. Data were stratified using the Scottish Index of Multiple Deprivation (SIMD), a small area measure of deprivation. Model outputs were quantified as deaths prevented or postponed (DPPs) by each intervention. Sensitivity analyses were conducted using Ersatz-based Monte Carlo simulations.

Results Between 2000 and 2010, 5770 fewer CHD deaths than expected occurred in Scotland; an estimated 3570 (62%) were attributable to reductions in blood pressure and serum cholesterol. Declines in blood pressure were responsible for approximately 2285 DPPs (minimum estimate 1630, maximum estimate 2915). The vast majority (2130 DPPs) came from population-wide blood pressure falls, with bigger absolute mortality decreases in the most deprived quintile compared with the least deprived (460 vs. 340 DPPs respectively); relative contributions were similar (37.2% and 37.5%). Anti-hypertension medications resulted in only 155 fewer deaths, with similar DPPs in the most (35) and least (30) deprived quintiles. Reductions in serum cholesterol resulted in 1280 fewer deaths; approximately 515 of these were attributable to population-wide changes in diet with more deaths prevented in the most deprived quintile compared with the least deprived (170 vs. 45 DPPs; relative contribution 13.8% and 4.7%). Conversely, approximately 770 fewer deaths were attributable to statin use, with very similar absolute numbers of deaths prevented in most (140) and least (140) deprived quintiles, but relatively greater contributions in the least deprived (15.4% vs 11.2%). Statin uptake was higher in the most deprived areas (17% vs 13.2%).

Conclusion Population-wide falls in blood pressure helped to reduce CHD mortality; however the benefit from hypertension treatment was small. Improved diet and statins for high-risk individuals both made important contributions to the fall in population cholesterol. Population-wide falls in blood pressure and reductions due to medical treatments for hypertension were equitable between socio-economic groups. Higher socio-economic groups appeared to benefit more from statins, probably due to better compliance; this may perpetuate inequalities.