Proficiency Testing for Urinary drug screening

Providing the best patient care requires laboratories to strive for the highest performance. One of the means for the same would be participating in the external proficiency testing programs. We report our laboratory's performance in the last three years in the urinary toxicology survey (UT) of College of American Pathologists (CAP). The lab receives three shipments of 5 samples each per year. CAP evaluations are based on scientific committee review, and participants are marked incorrect only if they have reported false positive results. We have reported 12 false positives, 5 in the year 2002, 6 in 2003 and 1 in 2004. Though false negatives are not ranked by CAP we went back into the details of each and reasoned out the same. They were either due to method limitations, or the lab's policy of not identifying the individual compounds like methylenedioxy methamphetamine, oxazepam, nordiazepam, and others, but reporting as a group like amphetamines, benzodiazepines, etc., and also due to lack of experience with a few drugs in our setting (verapamil, cimetidine, hydroxyzine, etc). Thus, thorough evaluation of the CAP results and timely corrective actions help us in gaining confidence and experience with new drugs and also know our method limitations. Hence every patient sample in the lab is analyzed and reported with thorough history evaluation and technical competence.