Box 2.

: Empirical evidence on scale and performance of primary care organisations

• Evidence from US managed care organisations suggests that the per capita cost of providing care is minimised at population levels that are no larger, and possibly smaller, than the average size of primary care groups and trusts
• Evidence from UK total purchasing pilots suggests that managerial economies of scale are exhausted at population levels smaller than the current average size of primary care groups and trusts
• Evidence on the effect of size on bargaining power with providers is ambiguous: larger primary care groups and trusts may not be permitted to move their business to another provider
• Optimal population size for commissioning varies widely depending on the services being commissioned
• There is some evidence of economies of scale in pooling risks, but the marginal gains from pooling diminish rapidly with increasing population size: primary care groups and trusts of average size do not face substantial risks of bankruptcy
• There is no evidence that clinical governance activity benefits from economies of scale: larger organisations encounter increased problems in sustaining professional commitment and involvement in quality improvement activity