Proficiency testing as a quality tool towards continuous improvement in the laboratory

The subject of proficiency testing as a quality tool stemmed from a lack of documented evidence on the value of blind proficiency samples versus double-blind proficiency samples. Unfortunately, the value of double-blind proficiency testing is often overlooked due to several inherent limitations. This study was conducted to support the hypothesis that running double-blind QC samples is a more accurate indicator of laboratory data quality than analyzing single blind QC samples. A blind versus double-blind study was conducted and results confirmed the hypothesis. Single blind proficiency testing has many merits, especially as a quality indicator. However, data generated using single blind QC samples has limitations due to special treatment by the analysts. This paper explores proficiency testing as a quality tool and how to use data generated from both blind and double-blind QC samples to continuously improve the processes in the laboratory.