Kategorien: Johner Institut

2 Kommentare

  1. Lucie | Montag, 11. Oktober 2021 um 12:23 Uhr - Antworten

    Dear Sir/Madam,
    I wanted to ask about the calculations of the cut-off value, is it needed for analytical sensitivity and specificity or for diagnostic sensitivity and specificity? One last question please, what does this mean:
    This Section shall provide a summary of analytical data with a description of the study design including methods for determining the assay cut-off, such as:

    the population(s) studied: demographics, selection, inclusion and exclusion criteria, number of individuals included;
    method or mode of characterisation of specimens; and
    statistical methods such as Receiver Operator Characteristic (ROC) to generate results and if applicable, define grey-zone/equivocal zone.

    how could one formulate this section in the technical documentation?
    Thank you again!
    Best regards, Lucie

    • Dr. Catharina Bertram | Dienstag, 12. Oktober 2021 um 14:53 Uhr - Antworten

      Dear Lucie,
      The calculation of a cut-off value may be applied in different contexts of use. For qualitative tests, the cut-off is defined as “the threshold above which the result is reported as positive and below which the result is reported as negative” (source: CLSI Guidance EP12-A2 “User Protocol for Evaluation of Qualitative Test Performance). Accordingly, the cut-off represents the medical decision point. Manufacturers establish the product-specific cut-off value based on the intended purpose of the IVD medical device and the claimed or desired diagnostic sensitivity and diagnostic specificity.
      The IVDR requires in Annex II, Section to describe the product-specific approach for assessing the IVD medical device’s cut-off as part of the technical documentation. The detailed information and wording depend on the intended purpose of your IVD medical device and the product-specific performance evaluation strategy. The cut-off is, e.g., dependent on the intended population and may vary with different specimen types. One approach to select the appropriate cut-off is to present diagnostic sensitivity-specificity pairs in a receiver operating characteristic (ROC) plot. Usually, manufacturers estimate the assay cut-off based on a smaller cohort during their analytical performance studies and validate the selected threshold during the clinical performance study based on a statistically validated sample size. The particular requirements for the documentation of the performance evaluation studies are specified in Annex XIII of the IVDR.
      Best regards, Catharina

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