Latent Print Proficiency Testing: An Examination of Test Respondents, Test‐Taking Procedures, and Test Characteristics

Proficiency testing is a key component of quality assurance programs within crime laboratories and can help improve laboratory practices. However, current proficiency testing procedures contain significant limitations and can be misinterpreted by examiners and court personnel (Garrett & Mitchell, 2018). To evaluate some of these limitations, we surveyed latent print examiners (n = 198) after they completed a Collaborative Testing Services, Inc. proficiency test. Additionally, we evaluated test performance and used a quality metric algorithm to evaluate the quality of test prints. Results do not suggest that respondents are dissimilar to the broader examiner population, although they may engage in different behaviors when completing tests versus casework. Findings show that proficiency testing contains prints of high quality and is perceived as both relatively easy and representative of casework. The test discriminated between inexperienced and experienced respondents, and verification procedures were largely ineffective in reducing errors. Objective quality metrics may provide a path forward to improving proficiency testing in a measurable manner

Performance of a revised cardiac troponin method that minimizes interferences from heterophilic antibodies

Background: Recent guidelines for use of cardiac troponin to detect cardiac damage and for cardiovascular risk stratification have made increasingly sensitive troponin assays important. Troponin assays continue to be plagued by interferences caused by heterophilic antibodies (HAs). We evaluated the performance of a revised cardiac troponin I (cTnI) assay designed to have increased analytical sensitivity and to minimize the effect of HAs. Methods: The revised Dade Behring Dimension(R) cTnI assay was evaluated according to NCCLS EP5-A at five institutions. Plasma samples from 14 309 patients were assayed by the original Dimension cTnI assay. To identify samples that may have interfering HAs, samples with values >1.4 mug/L were reanalyzed on the Dade Behring Stratus(R) CS cTnI assay. Samples with possible interfering antibodies were also analyzed before and after selective absorbance studies on the revised Dade Behring Dimension cTnI assay. Results: The limit of quantification in the revised method was 0.1 mug/L with imprecision (CV) of 11-17% at 0.1 mug/L. Values correlated well with the Stratus CS cTnI method: revised = 1.06(original) + 0.01; r = 0.98, S-y/x, = 0.25 mug/L). Falsely increased results consistent with myocardial infarction by the original Dimension cTnI assay and presumably attributable to HAs were identified in 0.17% of all patients with samples submitted for cTnI analysis. The revised Dimension cTnI assay eliminated the interference in 17 of 25 samples identified and greatly decreased the interference in the other 8. Conclusions: The revised Dimension cTnI method greatly minimizes the effect of interfering HAs. It also exhibits analytical performance characteristics consistent with recent guidelines for use of this assay to detect cardiac damage. (C) 2002 American Association for Clinical Chemistry

Validation Protocol: First Step of a Lean-Total Quality Management Principle in a New Laboratory Set-up in a Tertiary Care Hospital in India

Method validation is pursued as the first step in establishing Lean-Total Quality Management in a new clinical laboratory, in order to eliminate error in test results. Validation of all the new tests were done (with particular reference to alkaline phosphatase) by verifying reference intervals, analytical accuracy and precision, inter-assay and intra-assay variations, analytical sensitivity, limit of detection, linearity and reportable range, i.e. (i) Analytical measurement range (AMR) and (ii) Clinically reportable range (CRR). Our obtained reference range was within that of the manufacturer’s and showed high degree of analytical accuracy between two laboratories (r2 = 0.99). Precision was comparable with the manufacturer’s claim with inter-assay variation CV 1.04% and intra-assay variation CV 1.54%. Lowest limit of detection was 1.0324 ± 0.007 with CV 0.34%. AMR was also verified with CV 1.26 and 0.69%, for level 1 and level 2 control sera, respectively. The assay was linear with different dilutions. Lean concept was also verified with high recovery percentage. Validation ensures that accurate and precise results are reported in a clinically relevant turn around time