Comparison of the erythrocyte sedimentation rate measured by the Micro Test 1 sedimentation analyzer and the conventional Westergren method.

BACKGROUND

The erythrocyte sedimentation rate (ESR) remains the most widely used laboratory test for monitoring infections, inflammatory diseases and some types of cancer. Several test methods have been developed recently, and as a result, the safety and reliability of ESR testing procedures have improved. The purpose of this study was the comparison of two methods, the traditional manual Westergren method (reference method of the International Committee on Standardization in Hematology) and a new semiautomated technique, the Micro Test 1 for determining the ESR.

SUBJECTS AND METHODS

Blood samples were collected after a night's fasting from 200 hospitalized and ambulatory patients. Undiluted blood samples anticoagulated with K3 EDTA that had Micro Test 1 values ranging from 2-82 mm/h were used for comparison with the Westergren method.

RESULTS

Linear regression analysis comparing the Micro Test 1 and the reference method yielded satisfactory correlations and regression for samples (r=0.910; P=0.0001; y=4.91+0.86 x; Sy/x=6.85). A Bland-Altman analysis showed no evidence of systematic bias between the Micro Test 1 and the reference method.

CONCLUSION

The Micro Test 1 system was easy to use, had a satisfactory operative practicability, required minimal maintenance, and reduced contact with potential biohazards.