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Result distributions may change after a new IVD lot enters use, but the specimen population or laboratory conditions may also change. Complete lot traceability supports investigation without immediately attributing a difference to the product.
Define the assessment
Define relevant reagent, calibrator and control-material lots. Link each to its use period and instrument. Control results, patient-specimen comparisons and clinical performance can answer different questions; do not collapse them into one statement that the lot passed.
Worked example
For example, positivity increases after a lot change, while a different clinical-risk group also begins contributing specimens. The team first reconciles lot, instrument, quality-control and population information. It does not call the rise a lot problem or improvement without a suitable comparison. Further assessment addresses the specific unresolved question.
Practical checks
- Link lot-transition dates traceably to the relevant measurement records.
- Examine concurrent instrument, calibration and specimen-population changes.
- Assign technical and clinical ownership for unexpected patterns.
Decision and limitations
The report should identify lots and conditions evaluated. One acceptable control specimen does not represent every clinical range. Assess lot differences against intended use and available evidence; preserve historical classifications and disclose uncertain periods rather than silently rewriting them.
Frequently asked questions
- Does a difference after transition prove a lot effect?
- No. Investigate concurrent changes in specimens and other conditions.
- Is control material sufficient clinical evidence?
- It contributes to specific technical questions; explain its relationship to clinical performance separately.