Explaining variation in hospital admission rates between general practices: cross sectional study

Abstract Objectives To quantify the extent of the variation inhospital admission rates between general practices,and to investigate whether this variation can beexplained by factors relating to the patient, thehospital, and the general practice. Design Cross sectional analysis of routine data. Setting Merton, Sutton, and Wandsworth HealthAuthority, which includes areas of inner and outerLondon. Subjects 209 136 hospital admissions in 1995›6 inpatients registered with 120 general practices in thestudy area. Main outcome measures Hospital admission rates forgeneral practices for overall, emergency, and electiveadmissions. Results Crude admission rates for general practicesdisplayed a twofold difference between the 10th andthe 90th centile for all, emergency, and electiveadmissions. This difference was only minimally reducedby standardising for age and sex. Sociodemographicpatient factors derived from census data accounted for42% of the variation in overall admission rates; 45% inemergency admission rates; and 25% in electiveadmission rates. There was a strong positive correlationbetween factors related to deprivation and emergency,but not elective, admission rates, raising questions aboutequity of provision of health care. The percentage ofeach practice’s admissions to different local hospitalsadded significantly to the explanation of variation,while the general practice characteristics consideredadded very little.