Assessment of decision support for blood test ordering in primary care. a randomized trial.

BACKGROUND Different methods for changing blood test-ordering behavior in primary care have been proven effective. However, randomized trials comparing these methods are lacking. OBJECTIVE To compare the effect of two versions of BloodLink, a computer-based clinical decision support system, on blood test ordering among general practitioners. DESIGN Randomized trial. SETTING 44 practices of general practitioners in the region of Delft, the Netherlands. PARTICIPANTS 60 general practitioners in 44 practices who used computer-based patient records in their practices. INTERVENTION After stratification by solo practices and group practices, practices were randomly assigned to use BloodLink-Restricted, which initially displays a reduced list of tests, or BloodLink-Guideline, which is based on the guidelines of the Dutch College of General Practitioners. MEASUREMENTS Average number of blood tests ordered per order form per practice. RESULTS General practitioners who used BloodLink-Guideline requested 20% fewer tests on average than did practitioners who used BloodLink-Restricted (mean [+/-SD], 5.5 +/- 0.9 tests vs. 6.9 +/- 1.6 tests, respectively; P = 0.003, Mann-Whitney test). CONCLUSIONS Decision support based on guidelines is more effective in changing blood test-ordering behavior than is decision support based on initially displaying a limited number of tests. Guideline-driven decision support systems can be effective in reducing the number of laboratory tests ordered by primary care practitioners.