Comparison of Erythrocyte Sedimentation Rate Results of Test-1 and Automatic Westergren Device with Reference Westergren Method

Abstract

Aim: International Council of Standardization in Hematology (ICSH) suggests Westergren method as a reference method in erythrocyte sedimentation rate (ESR) measurement. There are lots of modified methods and devices which use different sample types recently. We investigated to compare the devices which are present in our hospital; Test-1 device that uses samples with EDTA and the device which is compatible with automatic Westergren method that uses infrared technique and studies with citrated samples; by using the reference method that is Westergren method. Method: From a total of 80 patients for ESR test, blood samples were taken at the same time into the tubes with K 2 EDTA and sodium citrate on 7 separate days; and after these blood samples arrived at our laboratory in 2 hours, they were studied with reference Westergren method and in Test-1 and automatic Westergren devices. These two methods were statistically compared with each other and also with the reference method by using concordance correlation coefficient and Passing-Bablok regression analysis method. Results: ESR result values were dispersed in the interval of 1-78 mm/hour, while R 2 values in the correlation of reference Westergren method with Test-1 and automatic Westergren devices were found as 0,86 (%95 Cl 0,801 to 0,913) and 0,978 (%95 Cl 0,967 to 0,985), respectively. R 2 value in the correlation between two devices was found as 0,898 (%95 0,846 to 0,933). In the Passing Bablok analysis, in the regression analysis of devices with reference method, intercept for Test-1 device was found as -0,5 (%95 Cl -2,42- 0) and the slope was 1,09 (%95 Cl 1-1,21) (y=-0,5+1,09x). Intercept for automatic Westergren device was found as -0,25 (%95 Cl -1,26-0) and the slope was 1,03 (%95 Cl 1-1,08) (y=0,25+1,03x). Intercept for comparison of these two systems was found as -0,14(%95 Cl –1,01-0) and the slope was 1,02 (%95 Cl 1-1,17) (y=-0,14+1,02x). There was no significant difference between the groups with student t-test (p>0,05). Conclusion: Test-1 method and automated Westergren method devices can be used reliably in the ESR measurement in routine laboratory as compared with reference Westergren method. At high ESR values Test-1 device has deviations from the reference method. We suggest that the evaluation of results of high sedimentation values be made carefully and for high ESR values comprehensive studies be supported by further research.