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The importance of correct stratifications when comparing directly and indirectly estimated reference intervals
Rainer Haeckel1, Werner Wosniok2
1Bremer Zentrum für Laboratoriumsmedizin, Klinikum Bremen Mitte, 28305Bremen, Germany.
Clinical Chemistry and Laboratory Medicine
|May 28, 2021
Summary
Neglecting stratification for biological variables like sex and age leads to inaccurate reference intervals (RIs). This discrepancy between direct and indirect RIs is often misunderstood as an error in the indirect method, not a failure in stratification.
Area of Science:
- Clinical Chemistry
- Laboratory Medicine
- Biostatistics
Background:
- Reference intervals (RIs) are crucial for interpreting laboratory test results.
- Comparisons of RIs, whether internal vs. external or direct vs. indirect, can reveal discrepancies.
- These discrepancies often stem from unaddressed pre-analytical, analytical, or biological variations.
Purpose of the Study:
- To investigate the impact of neglecting stratification on reference interval (RI) comparisons.
- To highlight the role of biological variables, specifically sex and age, in RI determination.
- To clarify misinterpretations arising from differences between directly and indirectly estimated RIs.
Main Methods:
- Examined the consequences of omitting stratification during RI determination.
- Focused on key biological variables affecting RIs: sex and age.
- Utilized alanine aminotransferase as a case study where RIs are influenced by both sex and age.
Main Results:
- Both direct and indirect methods yield erroneous RIs when stratification is inadequate.
- Failure to stratify impacts direct and indirect RI determination differently.
- Neglecting stratification for variables like sex and age is a primary cause of RI comparison discrepancies.
Conclusions:
- Inadequate stratification is a major driver of differences between direct and indirect reference intervals.
- The observed differences are frequently misattributed to errors in indirect RI estimation.
- Proper stratification is essential for accurate and comparable reference intervals.
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