Every six months the CPQA PT program offered prepared plasma samples containing pre-specified concentrations (unknown to CPLs) of up to 21 ARV analytes: abacavir (ABC), amprenavir (APV), atazanavir (ATV), darunavir (DRV), didanosine (DDI), efavirenz (EFV), emtricitabine (FTC), etravirine (ETR), indinavir (IDV), lamivudine (3TC), lopinavir (LPV), maraviroc (MVC), nelfinavir (NFV), nevirapine (NVP), raltegravir (RGV), ritonavir (RTV), saquinavir (SQV), stavudine (D4T), tenofovir (TFV), tipranavir (TPV), zidovudine (ZDV). In each round and for each ARV, 5 concentrations, spanning an expected therapeutic range of each ARV, as well as occasional concentrations below or above, were provided. Samples are prepared by an outside subcontractor and tested by the CPQA lab prior to distribution. PT samples were stored at −70 ± 15°C and then shipped on dry ice to participating laboratories with detailed instructions. Upon arrival, each laboratory confirmed sample integrity and indicated planned reporting of specific analytes. Results were reported either through an online Laboratory Data Management System (LDMS) or via a template which was then uploaded into the LDMS database. At the end of the submission period, a completeness evaluation was performed to confirm that all planned results were received; discrepancies were queried for resolution. To summarize the proficiency of individual labs, a pre-specified scoring algorithm was applied to the RCs (see next paragraph). The scoring algorithm reflects US Clinical Laboratory Improvement Act (CLIA) PT regulations[13 (link)]. After review and approval by the CPQA advisory board chair, a final report was sent to the participating laboratories (with laboratories de-identified) and key leadership (laboratories identified per network leader).
An individual RC is deemed Acceptable provided a concentration is present where expected, and the concentration is within 20% of the final target (FT)[14 (link)]. (If a concentration is reported as below the lower limit of quantification (BLQ), and the run lower limit was below 80%*FT, the concentration was labeled Unacceptable.) For a given prepared sample, if the number of labs reporting for that sample is large enough, the variability between CPLs is small enough (≤15%) and the percent deviation of the group mean (GM, determined after removal of outliers, if any)from the weighed-in value (WIV) is >5%, the FT is set to the GM. Otherwise, FT is set to the WIV. At the analyte level, a CPL’sperformance is deemed Satisfactory for the round provided at least 80% of RCs are Acceptable. If the CPL score is <80% for an analyte, the CPL submits a corrective action plan to reestablish accuracy; a root cause is requested. Finally, in accordance with CLIA rules, a lab is classified as successful for an analyte provided the round-specific score was Satisfactory in at least 2 of the last 3 rounds (including the current).
An individual RC is deemed Acceptable provided a concentration is present where expected, and the concentration is within 20% of the final target (FT)[14 (link)]. (If a concentration is reported as below the lower limit of quantification (BLQ), and the run lower limit was below 80%*FT, the concentration was labeled Unacceptable.) For a given prepared sample, if the number of labs reporting for that sample is large enough, the variability between CPLs is small enough (≤15%) and the percent deviation of the group mean (GM, determined after removal of outliers, if any)from the weighed-in value (WIV) is >5%, the FT is set to the GM. Otherwise, FT is set to the WIV. At the analyte level, a CPL’sperformance is deemed Satisfactory for the round provided at least 80% of RCs are Acceptable. If the CPL score is <80% for an analyte, the CPL submits a corrective action plan to reestablish accuracy; a root cause is requested. Finally, in accordance with CLIA rules, a lab is classified as successful for an analyte provided the round-specific score was Satisfactory in at least 2 of the last 3 rounds (including the current).
