A randomized controlled study of biochemical tests in primary care: interventions can reduce the number of tests but...

The use of laboratory tests increases worldwide, and to some extent their use is likely to be inappropriate. Although primary care is responsible for a substantial proportion of requests, this sector is less extensively investigated than hospitals.

We tested the effect of six combinations of four interventions applied to 313 primary care clinics, using vitamin D as model test (253,762 vitamin D results). We evaluated the changes in test numbers in the six intervention groups compared to the control group, and whether interventions resulted in more homogenous test use within groups or affected the distribution of test results. All interventions included information on vitamin D testing guidelines. Four groups were exposed to a non-interruptive alert in the ordering IT-system and in two groups this was supplemented by an interruptive alert. Half of the groups received monthly feedback reports.

Application of alerts, irrespective of the combination with feedback reports, resulted in significantly reduced test numbers (maximum -46%). Guidelines either alone or combined with feedback reports did not cause significant difference from the control group. The within-group requesting pattern changed significantly for only two of the groups. The distribution of low and normal vitamin D results within groups showed no signs of more appropriate use of the test in any of the groups.

Some of the interventions reduced the number of tests, but there were no indications of improved adherence to the guidelines. The interventions may have led to under-utilization of the test and thus should be used with care.