[Effects of written intervention on the number of laboratory studies per patient].

In the context of economic measures in health care we followed over a period of nine months the consequences of a written intervention on the attitude of house staff to prescribe laboratory tests. Since it is well known that these tests have a major impact on health costs several studies have been conducted to test whether costs can be reduced without sacrifice of treatment quality. The study was undertaken in 1997. It had three phases of three months duration each: one for observation, one with the intervention and a follow-up phase. The laboratory tests requested by eleven physicians for their patients during the first month after the initial visit were analyzed. During the intervention--phase six physicians chosen at random were informed about their own average as well as that of the entire group (mean of the entire observation period of all physicians). Unexpectedly the hypothesis that the number of laboratory tests requested per patient would drop only in the group of informed physicians and should stay the same for the physicians without this intervention did not materialize. The number of performed tests dropped in both groups.