Impact of insurance coverage type on laboratory test ordering behaviour of general practitioners

There exists much variation between GP's in the use of laboratory tests. Although the requesting pattern of GPs has been extensively described in the literature, little is still known of the factors which influence the GP's test ordering behaviour.

This study aimed to determine whether the payment scheme according to which general practitioners are reimbursed influences the laboratory test ordering behaviour.

The laboratory test ordering behaviour of the general practitioners of Tilburg, a town with 180,000 citizens in the south of The Netherlands, was studied during a four month period, in relation to the type of insurance coverage of the patients. Two types of insurance were considered: voluntary and compulsory. The data were collected from the laboratory administration and coupled with information obtained from two, interview rounds.

Two findings support the hypothesis that the type of insurance coverage of the patient, has an impact on the test ordering behaviour of the physician: The ratio between laboratory requests for sickness fund patients and patients with a private health insurance was found to depend on the fraction of persons with a private health insurance within the family practice. This was tested with multiple linear regression analysis. General practices were divided into two subgroups, those with many > 29%) and few (< 29%), voluntarily insured patients. Where a patient was privately insured it was found that relatively more tests were ordered. In case of general practices with many voluntarily insured patients this distinction disappears. The relative proportion of voluntarily insured patients was found to be an important variable in explaining the test ordering behaviour of general practice physicians in Tilburg.