Objective: To evaluate the long-term impact of an intervention designed to reduce the ordering of three tumor markers frequently prescribed for gastroenterologic diseases (carcinoembryonic antigen, alpha-fetoprotein, carbohydrate antigen 19-9).

Methods: A prospective study with time series analysis in a teaching hospital. Local clinical guidelines were developed and implemented through a new order form, designed as a reminder to the physician, restricting the ordering of laboratory tests. Ratios between the number of markers ordered and number of admissions were recorded during a 3-month period before and after intervention in the whole hospital and monthly on a 4-year period in two wards of the hospital (Department of Gastroenterology and Department of Internal Medicine). To evaluate the appropriateness of tumor marker orders, audits were performed on a sample of order forms, before and after (1 month and 2 years after) the implementation of the new order form.

Results: The analysis of covariance showed a significant effect of the intervention in the hospital (p < .01), and in the Departments of Gastroenterology (p < .01) and Internal Medicine (p < .007). The decrease of tumor marker orders ranged from 25% (Internal Medicine Department) to 55% (whole hospital). A similar decrease was observed for the three studied markers. The appropriateness of prescriptions increased from 54.6% before to 73.6% after the implementation of the new order form, but decreased to 52.9% 2 years after intervention.

Conclusions: Providing a reminder to clinicians through a specific order form represents an inexpensive and easy way to implement guidelines on use of laboratory tests.