Variation in coronary artery bypass grafting, angioplasty, cataract surgery, and hip replacement rates among primary care groups in London: association with population and practice characteristics.

Operation rates for common surgical procedures are known to vary widely both between areas within the same country and between countries. However, no studies in the United Kingdom have yet examined the variation in the use of important groups of surgical procedures among primary care groups. Data were obtained from the NHS Executive and the Department of Health on each of the 66 primary care groups in London that existed on 1 April 1999. These were used to estimate indicators for six main groups of variables: population estimates, mortality rates, Census data, benefits data, practice characteristics, and hospital admissions. The data were used to generate a number of population and practice variables describing the characteristics of each primary care group in London. We also obtained information at ward level by age and sex on the number of patients admitted for coronary artery bypass grafting (CABG) and angioplasty (PTCA); cataract surgery; and hip replacement in patients aged 65 years and over during the period 1997-1998. These data were used with population estimates to estimate directly age-standardized annual operation rates for each primary care group for the study period. Operation rates for the three groups of procedures examined in this study varied widely between the 66 primary care groups. The directly standardized combined CABG and PtCA rate varied from 28 to 193 per 100,000 (mean 80); cataract surgery rates from 167 to 618 per 100,000 (mean 291); and hip replacement in people aged 65 years and over from 74 to 363 per 100,000 (mean 202). Correlations between operation rates and population and practice variables were relatively weak. Multifactorial models explained 57 per cent of the variation in CABG and PTCA rates, 34 per cent of the variation in cataract surgery rates, and 27 per cent of the variation in hip replacement rates. There are wide variations in the operation rates for important groups of surgical procedures among primary care groups. These variations are poorly explained by differences in the population and practice characteristics of primary care groups. The underlying reasons for variations in operation rates need to be better understood if the ambitious targets for access to elective surgery outlined in the NHS plan are to be met.