Quality Assessment
Quality assessment is a means to determine the quality of results. It is usually an external evaluation of a laboratory's performance that relies on incorporating proficiency panels of well-characterized sera into the testing routine. External quality assessment (EQA) is now recognized as an essential component of quality assurance and is the only means to give the laboratory manager an independent means of ensuring that his routine quality control is adequate and effective. The National External Quality Assessment Scheme (NEQAS) is administered by the PHLS
The following are distributed under the NEQAS scheme:
- Hepatitis B serology
- HIV serology
- Rubella serology (IgM and IgG)
- General virus serology
- Virus isolation
- Electron microscopy
It is important for the participating laboratory to treat NEQAS specimens in the same manner as normal routine specimens. Rubella IgM and HIV currently lack national reference preparations, as opposed to rubella IgG and HBsAg. Occasionally, more difficult specimens than usual are distributed as "education" material, such as those containing very low levels of HBsAg or anti-HIV. Scores are not normally allocated for this type of specimen, but participants may find it useful to compare their results with those of their peers.
The scoring system for NEQAS is as follows
2 fully correct report
1 partially correct report e.g. partial identification of a virus or an equivocal serological result
0 erroneous result which would not have serious clinical consequences e.g. false negative rubella IgG
-1 erroneous result which would have serious clinical consequences, e.g. false negative HBsAg or anti-HIV
It is highly desirable for the laboratory itself to have an internal quality assessment program, whereby anonymous clinical samples are submitted to the laboratory. An internal quality assessment scheme can be used to monitor the quality of the work more frequently and accurately than EQA schemes, since EQA samples are usually received infrequently and they are usually treated differently from the routine specimens. Experience at laboratories that have an internal quality assessment scheme has generally been that internal schemes are much better at identifying quality problems in the laboratory than external schemes.