Clinical pharmacology quality assurance program: models for longitudinal analysis of antiretroviral proficiency testing for international laboratories.

Among National Institutes of Health HIV Research Networks conducting multicenter trials, samples from protocols that span several years are analyzed at multiple clinical pharmacology laboratories (CPLs) for multiple antiretrovirals. Drug assay data are, in turn, entered into study-specific data sets that are used for pharmacokinetic analyses, merged to conduct cross-protocol pharmacokinetic analysis, and integrated with pharmacogenomics research to investigate pharmacokinetic-pharmacogenetic associations. The CPLs participate in a semiannual proficiency testing (PT) program implemented by the Clinical Pharmacology Quality Assurance program. Using results from multiple PT rounds, longitudinal analyses of recovery are reflective of accuracy and precision within/across laboratories. The objectives of this longitudinal analysis of PT across multiple CPLs were to develop and test statistical models that longitudinally: (1) assess the precision and accuracy of concentrations reported by individual CPLs and (2) determine factors associated with round-specific and long-term assay accuracy, precision, and bias using a new regression model. A measure of absolute recovery is explored as a simultaneous measure of accuracy and precision. Overall, the analysis outcomes assured 97% accuracy (±20% of the final target concentration of all (21) drug concentration results reported for clinical trial samples by multiple CPLs). Using the Clinical Laboratory Improvement Act acceptance of meeting criteria for ≥2/3 consecutive rounds, all 10 laboratories that participated in 3 or more rounds per analyte maintained Clinical Laboratory Improvement Act proficiency. Significant associations were present between magnitude of error and CPL (Kruskal-Wallis P < 0.001) and antiretroviral (Kruskal-Wallis P < 0.001).

Practice patterns of testing waived under the clinical laboratory improvement amendments.

OBJECTIVES: To determine operational practices in laboratories operating under a Certificate of Wavier (waived laboratories), or equivalent, under the Clinical Laboratory Improvements Amendments (CLIA) of 1988 when performing tests designated as having an insignificant risk of an erroneous result (ie, waived tests). METHODS: Waived laboratories that were part of the Centers for Disease Control and Prevention Laboratory Sentinel Monitoring Network project in the states of Arkansas, New York, and Washington were surveyed about their quality control (QC) and quality assurances (QA) practices when performing waived testing. Arkansas and Washington sent out similar questionnaires, whereas on-site surveys were conducted in New York. The survey in Arkansas and Washington also included nonwaived laboratories. The New York visits were designed to pilot test a regulatory inspection program for limited testing sites, which, in New York, are roughly equivalent to laboratories operating under a CLIA Certificate of Wavier and/or Provider-Performed Microscopy but are generally not located in physicians' offices. Laboratories visited in New York were selected from a list of limited testing sites and were representative of that population. RESULTS: Arkansas received responses from 211 facilities (37% response rate), of which 38% had Certificates of Waiver. Washington received responses from 190 waived laboratories (71% response rate) and from 116 nonwaived laboratories (32% response rate). In New York, 607 of the 2751 limited testing laboratories were visited. Reporting laboratories in all 3 states most frequently performed testing for glucose, urinalysis, urine human chorionic gonadotropin, occult blood, and group A Streptococcus antigen, although other waived tests were performed less frequently. Washington found that 57% of waived laboratories followed manufacturers' QC requirements. Arkansas found that 58% of laboratories doing waived tests that required liquid controls performed these controls, and 59% performing waived testing requiring electronic controls used these controls. In New York, 68% of the laboratories complied with the manufacturer's QC requirements for a variety of tests. Being accredited by an external organization or affiliated with a more complex laboratory improved compliance. Nonwaived laboratories in Washington and Arkansas complied with manufacturer's instructions at a higher rate than did waived laboratories. Similar deficiencies in following CLIA requirements were found in other areas of laboratory operation. CONCLUSIONS: Just more than half of waived laboratories in 3 diverse states follow manufacturer's instructions for recommended QC and QA. These instructions help ensure that the test will produce results that have an insignificant chance of an error. Although we did not study the impact of this and other findings on patient care, the results show that imposing good laboratory practices by regulation alone was insufficient to ensure quality laboratory results in any location evaluated. A system that can continually provide accessible education on laboratory practices, coupled with new thoughts on the regulatory environment, is in order.

Adding value to antiretroviral proficiency testing.

BACKGROUND: Clinical trial specimens tested for antiretroviral (ARV) concentrations often require compliance with Clinical Laboratory Improvement Act and/or the Food and Drug Administration bioanalytical guidance. EXPERIMENTAL: The Clinical Pharmacology Quality Assurance Program (CPQA) designed 8 proficiency testing (PT) rounds over 4 years to assess precision, specificity and stability. RESULTS: Ten laboratories provided blinded proficiency data to support continued acceptable precision of ARV methods. Specificity samples identified little bias for individual methods; hemolyzed (87%) and lipemic (86%) results were ≤ 10% of their control results. Stability was established for ARVs in plasma at -70°C for 2.5-3.6 years. CONCLUSION: PT provided by the CPQA assured continued acceptability of individual laboratory assay performances for precision and specificity, and obtained ARV stability during long term storage.