Do patients with angina alone have a more benign prognosis than patients with a history of acute myocardial infarction, revascularisation or both? Findings from a community cohort study

Abstract

Aim: To compare prognosis for patients with a diagnosis of angina alone to patients postacute myocardial infarction (AMI) and/or revascularisation and/or angina. Design: Community-based retrospective cohort study. Setting: A random selection of 37 Irish general practices. Participants: 1,609 adults with ischaemic heart disease (IHD) identified in 2000/1. Intervention: Medical records searches and postal questionnaires in 2000/1 and 2005/6. Outcome measures: Primary: all-cause and IHD-related mortality. Secondary: acute myocardial infarction (AMI), cardiac artery bypass grafting (CABG) and percutaneous transluminal coronary angioplasty (PTCA); physical and mental health status as measured by SF36 and SF12; process of care measurements and behavioural risk factor outcomes. Results: Compared with patients with previous AMI and/or revascularisation, patients with angina alone had slightly lower risks of all-cause and IHD-related death: however, although hazard ratios of 0.73 (95% CI 0.55 to 0.98) and 0.65 (95% CI 0.44 to 0.98), respectively, were significant at the p<0.05 level, they were not significant at the p<0.01 level currently suggested as appropriate in observational research. Proportional hazards models identified no statistically significant differences in adjusted risks of subsequent AMI, CABG or PTCA between patients with angina-alone and those with other IHD. Over the 4.5-year follow-up, physical functioning was consistently lower among those with angina alone, and the extent to which physical functioning was increasingly impaired was slightly greater. Conclusions: Prognosis to death or cardiac outcomes for patients with angina alone was similar to those with previous AMI and/or revascularisation, while health status was poorer. The clinical importance of angina should not be underestimated in primary care. Further descriptive research is needed among representative community cohorts of people with angina.