Contribution of modern cardiovascular treatment and risk factor changes tothe decline in coronary heart disease mortality in Scotland between 1975 and 1994

Objective-To estimate the fall in coronary heart disease (CHD) mortality in Scotland attributable to medical and surgical treatments, and risk factor changes, between 1975 and 1994. Design-A cohort model combining effectiveness data from meta-analyses with information on treatment uptake in all patient categories in Scotland. Setting and patients-The whole Scottish population of 5.1 million, includin g all patients with recognised CHD. Interventions-All cardiological, medical, and surgical treatments, and all risk factor changes between 1975 and 1994. Data were obtained from epidemio logical surveys, routine National Health Service sources, and local audits. Main outcome measures-Deaths from CHD in 1975 and 1994. Results-There were 15 234 deaths from CHD in 1994, 6205 fewer deaths than e xpected if there had been no decline from 1975 mortality rates. In 1994, th e total number of deaths prevented or postponed by all treatments and risk factor reductions was estimated at 6747 (minimum 4790, maximum 10 695). For ty per cent of this benefit was attributed to treatments (initial treatment s for acute myocardial infarction 10%, treatments for hypertension 9%, for secondary prevention 8%, for heart failure 8%, aspirin for angina 2%, coron ary artery bypass grafting surgery 2%, and angioplasty 0.1%). Fifty one per cent of the reduction in deaths was attributed to measurable risk factor r eductions (smoking 36%, cholesterol 6%, secular fall in blood pressure 6%, and changes in deprivation 3%). Other, unquantified factors apparently acco unted for the remaining 9%. These proportions remained relatively consisten t across a wide range of assumptions and estimates in a sensitivity analysi s. Conclusions-Medical treatments and risk factor changes apparently prevented or postponed about 6750 coronary deaths in Scotland in 1994. Modest gains from individual treatments produced a large cumulative survival benefit. Re ductions in major risk factors explained about half the fall in coronary mo rtality, emphasising the importance and future potential of prevention stra tegies.