Table 1 Descriptions of statistically significant variables in final regression models

CHD HES rate

6-year crude rate of CHD hospital procedures per 1000 patients (i.e. proxy for CHD morbidity). Data source was the General Practice Research Database.

% patients aged 55–74

Proportion of patients in GP practice population aged 55–74 years. Data source was the individual GP practices.

% patients aged >75

Proportion of patients in GP practice population aged over 75 years. Data source was the individual GP practices.

LISI score

Low Income Scheme Index (LISI) score which is the proportion of prescriptions in GP practices which were exempt from payment due to low income (i.e. proxy for deprivation). Data source was the individual GP practices.

Ethnicity

Proportion of patients in GP practice population defined as South Asian. Data source was the 1991 Census.