Variations in health services utilization by primary care patients.

This study analyses how both ambulatory care groups (ACGs) and physician characteristics explain the variability in health-service use among primary care patients in Spain. During the period 1996-1997, data derived from 52,152 patients and their 38 respective primary care physicians were collected. The response variables were as follows: number of visits; diagnostic tests requested; and referrals to a specialist. ACGs are an important variable that should be taken into account in order to explain health-service utilization. As for professionals, age and the post they hold are essential factors. Most of the unexplained variability is caused by patient characteristics.