Abstract:

Introduction: Comparison of TSH values by analysis of retrospective data obtained from daily internal quality control (IQC) runs performed concurrently on Architect i2000 and cobas e601; the two platforms used to run TSH test for patient samples at The Nairobi Hospital, Kenya.

Method: Data analysis was carried out using R project version 3.2.3. Data was analyzed both in combination (N=590) and segregated as Level 2 (N= 297) and level 3 (N=293).  

Results: Shapiro-Wilk normality test returned normal distribution for level 2, abnormal distribution for level 3 and combined data on both platforms. Paired T-test for level 2 and Mann–Whitney U -Wilcoxon signed rank test for level 3 and combined data, indicated that the alternative hypothesis: true location shift is not equal to 0. Deming and Passing-Bablok regression analysis for level 2 and 3 showed a significant deviation in values between the two methods by a constant. Concordance correlation of the individual levels 2 and 3 is poor.

Discussion: The data demonstrates that there is a constant systematic error between the two methods, with cobas values reading higher each time, and that this difference is significant at both levels.

Conclusion: Regression analysis shows transferability of results from one method to another, however, the difference in means and the poor concordance correlation obliges a consideration of the TSH value results given by the lab especially so in the subclinical range (5 – 10) mIU/ml.

Keywords: Thyroid Stimulating Hormone, TSH, Architect i2000SR, Cobas e601

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