Uncertainty value of %CD4+T cell measurement

Abstract

       Laboratory results are important data that aid in diagnosis, monitoring, and prognosis. However, the variation of the results occurs once the same sample is retested due to several factors. Uncertainty of the measurement indicates how much these factors affect the result. The uncertainty of %CD4+T cell measurement within the Flow Cytometry Unit, Faculty of Associated Medical Sciences, Chiang Mai University were estimated by using the results of internal quality control and external quality assessment during 2012–2013 to comply with the requirements of ISO 15189: 2012. The procedures of this study included 1) Estimation of the uncertainty of measurement, 2) Reporting of the uncertainty of measurement, 3) Assessment of the uncertainty of measurement for clinical fitness purpose, and 4) Clinical use of the uncertainty information for clinical monitoring. The results of uncertainty measurements of the year 2012 and 2013 were 6.8% and 6.2% respectively at 95% confident level. In conclusion, the uncertainty of %CD4+T cell measurement is fit for clinical purpose and can be used in clinical monitoring of HIV-infected person.