Anticoagulant therapy monitoring with international normalized ratio at US academic health centers.

OBJECTIVE

To assess the extent of incorporation of international normalized ratio (INR) reporting in US academic hospitals.

DESIGN

Survey of academic hospital clinical laboratories in January 1995.

SETTING/PARTICIPANTS: Fifty-eight academic hospital clinical laboratories at institutions that are members of the University Health System Consortium.

MAIN OUTCOME MEASURES

The methods for monitoring oral anticoagulant therapy at the surveyed laboratories were determined. The extent of reporting of prothrombin time (PT), PT ratio, INR, and INR therapeutic range was determined.

RESULTS

All 58 of the responding hospital clinical laboratories reported INR in patients receiving oral anticoagulation. The median length of time that hospitals had been reporting INR was 24 months (range 3-108). A majority of hospitals continued to report PT values (95%) and PT reference ranges (93%) in addition to INR. Therapeutic INR ranges were reported by only 25 of the laboratories (43%). Of those that report INR ranges, many follow the published recommendations by the American College of Chest Physicians and the Food and Drug Administration. A majority of the hospitals (79%) do not confirm the accuracy of the international sensitivity index (ISI) for their own analyzers.

CONCLUSIONS

Contrary to previous reports, academic hospital clinical laboratories have now adopted the more accurate system of reporting INR values in addition to PT values in patients receiving oral anticoagulation. However, better reporting of INR ranges, use of more sensitive thromboplastins, and confirmation of the accuracy of the ISI for local analyses would further improve the monitoring of oral anticoagulation.