Oral anticoagulant therapy control: evidence that INR expression improves the inter-laboratory comparability of results--the Bologna oral anticoagulant control exercise.

The aims of the present study were: 1) interlaboratory normalization of prothrombin time (PT) testing for anticoagulant therapy control through calibration of customary thromboplastins against international reference materials, and 2) "on field" validation of the advantages offered by expression of results as International Normalized Ratio (INR) as opposed to percentage activity. PT tests were carried out over 8 days on the same normal subjects (16) and patients on oral anticoagulants (48) in the 9 laboratories of the Bologna area. The use of customary thromboplastins and coagulometers was maintained in all labs throughout the study. The main results were: 1) the interlaboratory CV of the prothrombin ratios obtained for each sample with all customary thromboplastins (5 different brands) was 15%, but was reduced to levels of 5.8 to 8.9 when using constant thromboplastin brands and batches; 2) the International Sensitivity Index (ISI) values obtained in the different labs were only slightly influenced by the use of different coagulometers; 3) comparable ISI values were obtained through direct calibration with the international reference material and through intermediate calibration with a locally selected standard; 4) use of INR values instead of percentage activity greatly reduced interlaboratory variability and significantly improved uniformity of anticoagulation level measurements, thus reducing the possibility of erroneous prescriptions. The Bologna exercise is therefore of educational value for laboratory and community doctors of the area in understanding and accepting the INR system.

Colorectal carcinoma screening attitudes and practices among primary care physicians in counties at extremes of either high or low cancer case-fatality.

BACKGROUND: To the authors' knowledge, physician attitudes and reported practices regarding colorectal carcinoma screening have not been studied in areas of highest risk for cancer death. METHODS: Medicare claims were used to calculate colorectal carcinoma 2-year case-fatality rates for counties with >100 incident cases of colorectal carcinoma between 1991-1993. All 2682 practicing primary care physicians in 20 counties with the lowest case-fatality rates (mean of 29.9%) and 19 counties with the highest case-fatality rates (mean of 47.8%) were surveyed regarding their screening procedures and attitudes. RESULTS: Among the 972 respondents (36.1%), the reported use of fecal occult blood testing (FOBT) and flexible sigmoidoscopy was similar in the low and high case-fatality counties. However, physicians who practiced in the high case-fatality counties were less likely to be trained in and to perform sigmoidoscopy themselves (37.0% vs. 45.6%; P<0.01). Moreover, practitioners in the high case-fatality counties were more likely than the other physicians to consider or plan enhanced FOBT and sigmoidoscopic screening in the near future. FOBT and sigmoidoscopy screening rates at the county level were associated negatively with cancer incidence rates, case-fatality rates, and metastatic disease rates, suggesting a potentially protective effect. CONCLUSIONS: Geographically targeted interventions are a potentially cost-effective strategy for focusing additional screening services on the highest risk populations. The primary care clinicians in these high risk areas are logical partners for these interventions by virtue of their high degree of readiness to change their current screening practices.