Availability of primary care doctors and population health in England: is there an association?

BACKGROUND: In the United States, an association has been proposed between better access to primary care and lower mortality. This paper reports an ecological analysis that evaluated whether population health was associated with general practitioner (GP) supply in England.
METHODS: Data were analysed for 99 health authorities in England in 1999. Health outcomes included standardized mortality ratios, infant mortality rate (per 1,000), hospital admissions with acute and chronic conditions (per 100,000), and teenage conception rates (per 1,000). The number of GPs per 10,000 population was included as explanatory variable. Confounders included the Townsend deprivation score, proportion of ethnic minorities, proportion in social classes IV and V, and proportion with limiting long-term illness. Analyses were by linear regression weighted for population size.
RESULTS: Higher GP supply was associated with lower mortality in univariate analyses. After adjusting for deprivation score, ethnic group and social class, the standardized mortality ratio for all-cause mortality at 15-64 years decreased by -5.2 (95 per cent confidence interval -8.3 to -2.0, p = 0.002) per unit increase in GP supply. After additional adjustment for limiting long-term illness, the decrease was -3.3 (-6.7 to 0.1, p = 0.060). In the fully adjusted model, each unit increase in GP supply was associated with a decrease in hospital admission rates for acute conditions (-14.4, -21.4 to -7.4 per 100,000, p < 0.001) and chronic conditions (-10.6, -17.2 to -4.0, p = 0.002).
CONCLUSIONS: In England, lower supply of GPs was associated with increased hospital utilization, but a strong univariate association with mortality might be explained by confounding.