Appendix 5: Table showing some examples of evaluation, validation and verification of diagnostic methods Evaluation Validation Verification Example 1 New method Revalidation of Existing method with compared with modified assays: defined performance: existing methods: an example is If a laboratory is Evaluating the results the use of ethidium considering the use of a of a new bromide in gel validated commercial chromogenic electrophoresis for kit for an assay based commercial media for visualisation of DNA on isolation of ESBL in agarose or published literature with producing acrylamide gels is validation data, some Enterobacteriaceae replaced with the form of verification will and then comparing use of SYBR Green be need to be done by with MacConkey agar which is not the laboratory to currently used. This is carcinogenic or determine whether the done to compare their toxic. This should be assay complies with specificity and revalidated to either the kit sensitivity. ensure that it works manufacturer’s or the well in the assay. author’s assertions. Example 2 Identifying Clostridium Standard method Existing method used perfringens genes used outside after modification: using real time PCR intended scope: using the first example and then comparing Acridine orange above in the validation these PCR results to stain is used for column, after the conventional PCR staining of revalidation of a methods (gel Trichomonas modified assay is done; electrophoresis) used. vaginalis smears but it should still be verified where used outside by the user to ensure its scope for that it gives the desired example, in the results. staining of clue cells, laboratories should ensure that this is validated. Example 3 Evaluation of PCR Laboratory Acquiring of new results for Clostridium designed equipment/machinery: perfringens genes methods/assays: Verification of new using the Lightcycler An example is where equipment used should machine and then a laboratory be performed by the comparing it with the
Appendix 5: Table showing some examples of evaluation, validation and verification of diagnostic methods Evaluation Validation Verification Example 1 New method compared with existing methods: Evaluating the results of a new chromogenic commercial media for isolation of ESBL producing Enterobacteriaceae and then comparing with MacConkey agar currently used. This is done to compare their specificity and sensitivity. Revalidation of modified assays: an example is the use of ethidium bromide in gel electrophoresis for visualisation of DNA in agarose or acrylamide gels is replaced with the use of SYBR Green which is not carcinogenic or toxic. This should be revalidated to ensure that it works well in the assay. Existing method with defined performance: If a laboratory is considering the use of a validated commercial kit for an assay based on published literature with validation data, some form of verification will be need to be done by the laboratory to determine whether the assay complies with either the kit manufacturer’s or the author’s assertions. Example 2 Identifying Clostridium perfringens genes using real time PCR and then comparing these PCR results to the conventional PCR methods (gel electrophoresis) used. Standard method used outside intended scope: Acridine orange stain is used for staining of Trichomonas vaginalis smears but where used outside its scope for example, in the staining of clue cells, laboratories should ensure that this is validated. Existing method used after modification: using the first example above in the validation column, after revalidation of a modified assay is done; it should still be verified by the user to ensure that it gives the desired results. Example 3 Evaluation of PCR results for Clostridium perfringens genes using the Lightcycler machine and then comparing it with the Laboratory designed methods/assays: An example is where a laboratory Acquiring of new equipment/machinery: Verification of new equipment used should be performed by the
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