Multivariate delta check method for detecting specimen mix-up.

Among laboratory mistakes, "specimen mix-up" is the most frequent and the most serious. According to the Clinical Chemistry Laboratory Error Report of Toranomon Hospital, specimen mix-up was often detected when there were many large discrepancies between the results of a test and the results of a previous test. We present here a checking method to detect specimen mix-up. The method, which we call the "multivariate delta check" method, is an extension of the "delta check" method first presented by Nosanchuk and Gottmann (Am. J. Clin. Pathol. 62:707, 1974). Clinical evaluation has demonstrated the effectiveness of the method.