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Patient-based real-time quality control (PBRTQC) has many uses in a laboratorian’s toolbox. It can help with external quality assessment and postmarket surveillance of in vitro diagnostics. PBRTQC’s customized approach also allows it to detect bias changes with great sensitivity, and it’s not expensive to set up. However, for PBRTQC to work efficiently, labs need to be well-versed on this approach’s analytical characteristics and the patient populations they serve.
In September’s Clinical Chemistry, Tony Badrick, PhD, queries members of the International Federation of Clinical Chemistry and Laboratory Medicine Working Group on PBRTQC about the best assays, software needs, and the role of PBRTQC in a lab’s total quality management system. The panel includes Andreas Bietenbeck, Alex Katayev, MD, Huub H. van Rossum, PhD, Mark A. Cervinski, PhD, and Tze Ping Loh, MB, BCh, BAO.
“The techniques of PBRTQC are now being more widely discussed by laboratory personnel as the advantages become apparent,” Badrick told CLN Stat. Labs should be aware of the basis of PBRTQC and how it might integrate with their current quality control (QC) strategy. “This will allow them to better interact with instrument vendors when the topic arises,” he said.
The panelists addressed transitions head on, discussing how PBRTQC can integrate with internal quality control, or iQC.
Working in a hospital-based lab with low daily production, van Rossum said his lab considered PBRTQC for analytical quality assurance and discovered that measuring iQC by internal control samples alone wouldn’t be sufficient. “We, therefore, have applied PBRTQC for tests whereby iQC is limited, in the sense that we experience a rapid onset of critical errors or temporary assay failures, or for tests with sigma metric values less than or equal to 4. By introducing PBRTQC procedures into the QC plan and by validating the PBRTQC error detection, we also have been able to reduce the number of quality-control sample measurements,” explained van Rossum.
Katayev’s large clinical reference laboratory, which has a high testing volume, has used PBRTQC for routine chemistry and immunoassay tests. “However, we are still using two layers of QC: iQC and PBRTQC that are nicely complementing each other,” he added. His lab runs iQC at the start of shifts to ensure accurate calibration and maintenance of instrumentation.
Loh offered some details on PBRTQC software. “When a significant analytical error is suspected, one can extract a period of laboratory data and calculate simple moving statistics (e.g., [moving average] or moving median) to observe the trend of the results,” he said. This informs labs about assay performance and confirms hunches about analytical performance. “Nevertheless, the output should be interpreted carefully and in conjunction with other forms of quality control (iQC and proficiency testing) data,” continued Loh.
Labs can use simple spreadsheet applications such as Microsoft Excel or Google Sheets to assist with this process. Some lab professionals use Microsoft Excel’s Analyse-it, an add-in software product, to compile test evaluation results. The software has built-in moving statistics applications, added Loh.
The panelists also discussed which assays work best—or don’t work at all—with PBRTQC. “In general, PBRTQC works best with analytes that have a relatively small measuring range,” noted Bietenbeck. Many extra-analytical factors affect its performance. It’s also not compatible with individual point-of-care tests. “Measurements from a glucometer that is used by only one patient reflect only the changes in this particular patient and cannot be used for PBRTQC,” he added.
Labs generally aren’t as well versed in PBRTQC compared to iQC. Cervinski said his lab is working on steps to educate staff on troubleshooting PBRTQC problems.
“Starting the staff with ‘simple’ moving statistics using simple spreadsheets whenever there is a significant laboratory error can help introduce the concept to the staff. Protocolization of troubleshooting steps similarly to iQC can also reduce the barrier,” suggested Cervinski. To simplify user experience, labs should recruit statistically inclined staff and hide as many statistical details as possible within the software from the routine team.
Read this month’s Clinical Chemistry to get a straightforward tutorial on PBRTQC from the experts. August’s Clinical Chemistry provided an overview of PBRTQC.