Comparison of specialty referral rates in the United Kingdom and the United States: retrospective cohort analysis

Abstract
We included non-pregnant patients aged 0 to 64 years, with at least six months of enrolment on a health plan or general practice registration and at least one consultation with their primary care physician during 1996 (US) or 1997 (UK). The US sample comprised 384 693 patients from five health maintenance organisations. All US patients had been assigned physician gatekeepers, who authorised specialty referrals. We used the general practice research database for the UK sample (n=757,680).1