Objective: To describe the types of laboratory test done in general practice, and to investigate whether practice characteristics were associated with the implementation of certain tests or instruments.
Setting: A questionnaire was mailed to an 8% random sample of Norwegian GPs.
Results: 85% responded; and we obtained data from 175 office laboratories. Medical secretaries did most of the analytical work. The "basic" repertoire consisted of haemoglobin, ESR, glucose; urine test strips, microscopy, culture, and HCG; and faecal occult blood. Group practices had a larger repertoire than had solo practices. Overall, 34% of the practices had urine strips with fields for leucocytes and nitrite, 26% had a cell counter, and 17% did clinical chemistry. A large number of different test methods and instruments were in use, but in most cases one or two brands had a market share of more than 50%. Logistic regression showed that employing a medical laboratory technician was associated with a large analytical repertoire, and the use of cell counters and clinical chemistry analyzers. The GP's form of payment (fixed or fee-for-service) did not influence the repertoire.
Conclusions: The diversity of test methods and instruments makes quality assurance difficult, and recommendations are overdue.