Relation between general practices' outpatient referral rates and rates of elective admission to hospital.

OBJECTIVE: To examine the variation in rates of admission to hospital among general practices, to determine the relation between referral rates and admission rates, and to assess the extent to which variations in outpatient referral rates might account for the different patterns of admission. DESIGN: A comparison of outpatient referral rates standardised for age and sex and rates of elective admission to hospital for six specialties individually and for all specialties combined. SETTING: 19 General practices in three districts in Oxford Regional Health Authority with a combined practice population of 188 610. MAIN OUTCOME MEASURES: Estimated proportion of outpatient referrals resulting in admission to hospital, extent of variation in referral rates and admission rates among practices, and association between admissions and outpatient referrals. RESULTS: Patients referred to surgical specialties were more likely than those referred to medical specialties to be admitted after an outpatient referral. Overall, the estimated proportion of patients admitted after an outpatient referral was 42%. There were significant differences among the practices in referral rates and admission rates for most of the major specialties. The extent of systematic variance in admission rates (0.048) was similar to that in referral rates (0.037). Referral and admission rates were significantly associated for general surgery; ear, nose, and throat surgery; trauma and orthopaedics; and all specialties combined. For most specialties the practices with higher referral rates also had higher admission rates, casting doubt on the view that these practices were referring more patients unnecessarily. CONCLUSION: Rates of elective admission to hospital vary systematically among general practices. Variations in outpatient referral rates are an important determinant of variations in admission rates.