The influence of supply-related characteristics on general practitioners' workload.

The workload of general practitioners (GPs) is usually defined in terms of the number of hours worked (divided in time spent on different practice tasks), rates of contact (office consultation and home visit rates) and length of consultations. They are influenced by two groups of factors: demand-related influences and supply-related influences. Demand-related influences refer to the list sizes of GPs and the composition of the practice population. Supply-related influences refer to the way GPs themselves manage their workload. In this article the relative influence of demand- and supply-related variables on the workload of Dutch GPs is assessed. The data for this analysis has been collected as part of the Dutch National Survey of Morbidity and Interventions in General Practice. We draw on four data sources: a three months recording of all contacts between GPs and their patients, a census of the practice population of the GPs, a mailed questionnaire among GPs and a one week diary kept by the GPs. The population consists of 168 GPs. The number of hours spent by GPs on practice activities is mainly determined by demand-related characteristics. List size and the percentage of elderly on the list are positively related to the time spent on direct patient care. Running a free flow consultation hour is the only factor on the supply side with an additional effect. GPs supervising a trainee and those with a larger percentage of elderly and publicly insured patients on their list spent more hours on other activities such as practice administration, deliberation and reading medical literature. List size and the percentage of elderly on the list have a negative influence on the office contact rate, while the percentage of low educated patients on the list and the number of practice secretaries per GP have a positive impact. Furthermore, GPs without a free flow consultation hour and those working in health centres tend to have smaller office contact rate than the others. Home visit rates are smaller when the practice secretaries provide a higher percentage of consultations in the practice, in single handed practices and in the case of female GPs. However, the percentage of elderly on the list is the main determinant of the home visit rate. The average length of consultations is not substantially affected by either supply- or demand-related characteristics.