Enact Effective P&Ps for Proficiency Testing

March-April 2015 - Vol. 4 No. 2 - Page #12

Q&A with Eugenio Zabaleta, PhD Ohio
Health MedCentral Mansfield Hospital

Medical Lab Management: Do you have a standard set of policies & procedures (P&Ps) for quality assurance (QA) activities related to the equipment you use?
Eugenio Zabaleta: While the simple answer is yes, behind that answer is a systematic approach to quality that makes the query more complex. From a broad perspective, the governing idea is that the accuracy and reliability of laboratory testing is essential to positive patient care. To achieve a consistently high level of accuracy and reliability, the laboratory must ensure the quality of its performance by first guaranteeing the quality of all laboratory processes (pre-analytical, analytical, and post-analytical), and second, by detecting and reducing errors. Last, the lab must seek to improve accuracy and reliability on both an intra-lab and inter-lab basis, all while actively containing costs. When discussing a systematic approach to quality, we must keep in mind these aspects and concepts:

  • Quality System: The organizational activities, infrastructure, resources, policies, procedures, plans, processes, responsibilities, and leadership necessary to implement a total quality management program.
  • QA Plan: To identify and prevent laboratory errors by implementing processes that systematically check for the quality and validity of laboratory results. A comprehensive QA plan should include a process and performance improvement plan.
  • Quality Control (QC): Comprising a set of laboratory methods, procedures, techniques, and activities used to monitor the analytical performance of laboratory tests performed.
  • Proficiency Testing (PT): Also called inter-laboratory comparison, PT is the testing of unknown samples, provided by and returned to the same CMS-approved PT program for analysis using CLIA grading criteria. The results are then returned to the laboratory to indicate their accuracy of testing. CMS and accreditation organizations routinely monitor laboratory performance via several PT challenges a year.

Thus, in order to implement an effective quality system approach, laboratories need to prepare and develop policies (what to do), processes (how it should happen), and procedures (how to do it) for all clinical testing.

MLM: What are the PT requirements for the equipment in your laboratory?
Zabaleta: Basic PT requirements for laboratory operations are usually dependent on the CMS-approved PT program to which each lab subscribes. At OhioHealth MedCentral Mansfield Hospital in Mansfield, Ohio, most of the analytes we use come in three shipments per year (a few come in only two); each shipment contains two to five PT challenges. 

We are in the process of adopting automated PT processes. Currently, the supervisor of each area enters PT results manually on the CAP Web site, reviews the information, and then submits them. Automating the process will enable us to send PT results directly from our instruments to the online CAP portal. Likewise, we are currently beta testing a process that will allow us to send PT results from our LIS, automatically, whether results are entered manually (for manual tests) or uploaded from the instruments. 

MLM: What is the relationship between PT and internal QA activities?
Zabaleta: In order to consistently provide accurate and precise results, the laboratory must maintain full control over all testing processes, including the identification, correction, and prevention of errors. Thus, strong PT performance is evidence of a strong QA program. However, no matter how comprehensive your processes, random error can still occur when processing PT samples. 

QC shifts are a common cause of PT failure for chemistry automation, which is why the Levey-Jennings Control chart and the Westgard Rules are such valuable tools for QC evaluations.

MLM: What is the process for responding to outlier PT results?
Zabaleta: When a laboratory receives an unsatisfactory PT result, remediation and prevention plans should be enacted that include the following steps:

  1. Upon receipt of an unsatisfactory PT result, the cause must be determined. Root cause analysis (RCA) is one tool that can help establish causation. In my opinion, the RCA process is more effective when executed by a team. The team should consist of those directly involved in the testing (ie, a bench tech), as well as the section manager, QA representatives, and the laboratory medical director. 
  2. Once the error is identified, it should be classified as being one or a combination of the following: clerical or results evaluation error; methodology, technical, or PT material(s) problem; or no viable explanation. Errors can be random or systematic, so analyzing QC data from the same time period as the unsatisfactory PT should help determine the type of the error.
  3. Corrective action, based on the cause and nature of the error, must be taken, and patient testing data from the time of the unsatisfactory PT may need to be reviewed to determine if patient care was affected.
  4. If patient care was affected, appropriate remediation should include full documentation of all actions taken after the unsatisfactory PT result.
  5. Once the error has been corrected, process improvement measures should be considered to help prevent reoccurrence.
  6. Lastly, the laboratory’s medical director should review the entire remediation process and approve it for submission to the lab’s CMS-approved PT program.

MLM: How should PT be run and resulted?
Zabaleta: This is an important issue that has been a focus of CMS in recent years. There are two main PT testing directives:

  • The laboratory must test PT samples by the same methods and personnel, and in the same manner, as normal patient samples (CAP COM.01600).1
  • The laboratory cannot refer PT samples to, discuss PT results with, or receive PT samples from, another laboratory (CAP COM.01800).1

Under certain circumstances, these two principles can be incompatible, so it is important to seek out and understand the guidance provided by CMS and your facility’s accrediting agency. 

For example, a laboratory may perform in-house HIV screen testing for all STAT orders, needlestick injuries, and accidental blood exposures, but may send all positive results to a reference laboratory for confirmatory testing (eg, western blot). If the laboratory must test PT samples in the same manner as it tests patient samples, it would end up sending all positive PT samples to a reference lab, which would violate the other directive of not referring PT samples to another laboratory. Fortunately, CMS has considered this scenario. As of the CAP Accreditation Program’s most recent revision to the All Common Checklist, section COM.01900 – PT Referral requires a policy that prohibits referral of proficiency testing specimens to another laboratory.1 However, a note to this section states, “This prohibition takes precedence over the requirement that proficiency testing specimens be handled in the same manner as patient specimens.” This is just one example of the complexities tied to PT activities in the clinical lab. Thus, each lab should seek out the CMS-mandated guidance provided by their PT program and incorporate those tenets into PT-related SOPs.  

MLM: Any parting thoughts on the current and future states of PT testing?
Zabaleta: Ultimately, CMS, CLIA, CAP, and other accreditation organizations want laboratories to test PT samples in the same way they test patient samples, as long as laboratories are not referring PT samples or discussing PT results with each other. But any clinical laboratory practitioner can think of scenarios that complicate the issue. As the conditions governing PT continue to evolve, new questions will arise. A common question for management is whether to inform techs that they are processing a PT sample. Common sense says not to inform the tech in an attempt to maintain the same working conditions present for a normal patient sample, but if those conditions involve sending a positive result out for confirmation, the tech would unknowingly be set up to fail. Ultimately, techs should know they are performing PT, but also they should be informed of the need to process the PT sample exactly as a patient sample. Likewise, should PT be assigned randomly or on a rotation among staff members? Guidance seems to suggest a standard rotation is best, as this ensures that all staff members who process patient testing under normal conditions also perform PT.

These are just a few PT-related concepts that are being considered by practitioners and regulatory bodies alike. Regardless, the value and importance of PT is clear. The onus then falls on each laboratory to use the aggregate data to improve processes and mitigate errors as much as possible.


  1. College of American Pathologists, Northfield, IL. CAP Laboratory Accreditation Program; All Common Checklist. April 21, 2014. 

Eugenio Zabaleta, PhD, is a clinical chemist at OhioHealth MedCentral Mansfield Hospital in Mansfield, Ohio. He graduated from the Catholic University of Cordoba in Argentina with a degree in biochemistry and received his PhD in chemistry from the University of Akron. 


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