Variations in use of cardiology services in a health authority: comparison of coronary artery revascularisation rates with prevalence of angina and coronary mortality.

OBJECTIVE

To explore the relation between rates of coronary artery revascularisation and prevalence of angina to assess whether use of health services reflects need.

DESIGN

Prevalence of angina symptoms determined by postal questionnaire on 16750 subjects (18 to 94 years). Comparison of data on use of coronary artery revascularisation with prevalence of symptoms and mortality from coronary heart disease.

SETTING

Health authority with population of 530000.

SUBJECTS

Patients admitted to hospital for coronary heart disease; patients who died; and patients undergoing angiography, angioplasty, or coronary artery bypass graft. Cohort of 491 people with symptoms from survey.

MAIN OUTCOME MEASURES

Pearson's product moment correlation coefficients for relation between variables.

RESULTS

Overall, 4.0% (95% confidence interval 3.7% to 4.4%) of subjects had symptoms. Prevalences varied widely between electoral wards and were positively associated with Townsend score (r = 0.79; P < 0.001), as was mortality, but the correlation between admission rates and Townsend score was less clear (r = 0.47; P < 0.01). Revascularisation rate and Townsend score were not associated. The ratio of revascularisation to number experiencing symptoms was inversely related to Townsend score (r = 0.67; P < 0.001). The most deprived wards had only about half the number of revascularisations per head of population with angina than did the more affluent wards. In affluent wards 11% (13/116) of those with symptoms had coronary angiograms compared with only 4% (9/216) in poorer wards (chi 2 = 4.96; P = 0.026). Townsend score also inversely correlated with revascularisations per premature death from coronary heart disease (r = 0.55; P < 0.01) and revascularisations per admission for myocardial infarction (r = 0.47; P < 0.01).

CONCLUSION

The use of interventional cardiology services is not commensurate with need, thus exhibiting the inverse care law.