FMEA made simple

February 22, 2007

Sometimes, something is presented that is so clear that it is worth reproducing. This is FMEA in a nutshell from the following source.



You’re either part of the problem or part of the solution

February 18, 2007


Westgard bemoans the current process of establishing performance claims for assays.  He states that

“There is one major fault with this approach [precision, accuracy, linear range, reference range(s), etc.]. Manufacturers do not make any claim that a method or test system provides the quality needed for medical application of the test results, i.e., FDA clearance does not require a claim for quality! To do so, a manufacturer would need to state a quality specification, e.g., the allowable total error, the maximum allowable SD, or the maximum allowable bias, then demonstrate that the new method or test system has less error than specified by those allowable limits of error.”

You’re either part of the problem or part of the solution. In this case, Westgard is part of the problem. His suggestion of allowable total error as stated above sounds good, but as I have pointed out many times,

  • Westgard’s maximum allowable total error is for a specified percentage of results – often 95% – which allows for too many results to fail to meet clinical needs
  • Westgard’s suggested testing procedures as described by his quality control rules fail to include all contributions to total error

Thus, 5% of a million results means that there could be 50,000 medically unacceptable results – that’s not quality. When one tests with control samples, one cannot detect interferences, which is often a source of important clinical laboratory errors so all of Westgard’s control quality algorithms for total error are meaningless – they inform about a subset of total error.

Things are improving. In the FDA draft guidance for CLIA waiver applications, FDA requires use of error grids (such as those in use for glucose) and demonstration of lack of erroneous results as defined in those error grids in addition to total allowable error. Many of my essays stress the need to go beyond total allowable error – as used by Westgard – and to put in place procedures to estimate erroneous results (1).


  1.  Jan S. Krouwer: Recommendation to treat continuous variable errors like attribute errors. Clin Chem Lab Med 2006;44(7):797–798.

Risk management and the clinical laboratory

February 13, 2007

The conventional wisdom is that errors in the clinical lab are usually (>90%) associated with pre-analytical and post-analytical processes rather than the analytical process. Yet much of the effort in preventing errors in assays deals with the analytical process.

There have been several ISO standards devoted to quality in the clinical laboratory:

ISO 15189 – Medical laboratories — Particular requirements for quality and competence ISO 17025 – General requirements for the competence of testing and calibration laboratories ISO 13485 – Medical devices — Quality management systems — Requirements for regulatory purposes

There is also an ISO standard devoted to risk management.

ISO 14971 – Medical devices — Application of risk management to medical devices

None of the standards will be of much help to reduce errors in the clinical laboratory

For example, in the first three standards, under the section “corrective action” in one standard it is stated that the laboratory shall establish a policy and procedure for implementing corrective action. Another standard goes into more detail by stating that an investigation process shall be included to determine the underlying cause(s) of the problem. Because of copyrights, I can’t reproduce these sections, but I don’t see that people in a clinical laboratory would say after reading this section – “aha, now I know exactly what to do”

The standard on risk management is much more informative but does not provide detailed guidance on risk management tools or a worked example that would help a clinical laboratory to set up a risk management program. Moreover, this standard is for manufacturers, not users of devices such as clinical laboratories. This is an important point, since process errors within a clinical laboratory can and have contributed to patient harm, including deaths (1).

Some comments on ISO 14971 – edited 11/21/07


EP18 to the rescue

The CLSI standard EP18 is currently being revised, EP22 and EP23 are new documents in preparation. All documents deal with aspects of risk management.

EP18 has a new title: Risk Management Techniques to Identify and Control Laboratory Error Sources

EP18 describes how to use two tools: FMEA – in order to reduce potential errors, and FRACAS – in order to prevent the recurrence of observed errors. Each is illustrated with worked examples.

A remaining issue

There is no current regulatory requirement for a clinical laboratory to perform risk management as described by EP18. Moreover, as this document has been developed, clinical laboratory subcommittee members expressed some reluctance to use these “industry tools”. There is no easy answer to this.

Perhaps, the fact that adverse events traced to clinical laboratory error (1) are amenable to prevention using these tools will help. The risk of litigation and fines (2) might also be a motivating factor. The rest of the hospital does have a regulatory obligation to perform at least one FMEA per year.


  1. Pennsylvania Dept. of health – health department announces preliminary results of St. Agnes investigation
  2. Pennsylvania Dept. of health – health department orders St. Agnes medical center to pay $447,500 fine