Para Refletir: Mind the Gap: Difference between knowledge and action in the laboratory

Saiu no The Westgard Rules, Blog do site do James Westgard: http://james.westgard.com/

Trata-se de um texto para a gente refletir, a respeito do que sabemos, e não sabemos, de como encarar os dados provenientes de controle interno de qualidade (CQI), e de como as pessoas apresentam diferentes compreensões de problemas conforme são apresentados.

Boa Leitura:




Mind the Gap: Difference between knowledge and action in the laboratory: "

Posted by Sten Westgard, MS

In June of this year, Zoe Brooks presented an AACC-sponsored webinar with the title, Laboratory QC: Bridging the Gap Between Theory and Practice. During this webinar, Zoe presented a poll and more than 100 participants responded. The results are very interesting...

When asked to agree or disagree with this statement, "Method quality is OK if all the results on a QC chart are within +/- 2 SD of the Mean" only 67% of the respondents said No. (I suppose we should be encouraged with that result? More than a majority of laboratorians have learned the most basic lesson of QC.)

But then Zoe did a clever thing. She presented participants with this graph:

Again, she asked, is this method OK or not or is there not enough information? Now only 29% of the participants answered that there was not enough information to make a decision.

Here's the trick: The two questions are the same. The first is a verbal presentation, while the second is a graphic presentation, of the same situation.

Let's be clear. When presented with the theoretical statement, 67% of the participants recognized that using 2sd limits as accepability critieria was not a good idea. But when presented with an actual example in a graph illustrating that theory, about half of those people did use 2sd limits as acceptability criteria. Let's estimate that roughly a third of the participants knew the correct theory, but acted incorrectly in practice.

The moral: even among experienced laboratorians, there is a lot of room for improvement.

I suspect if the poll had asked what rules were actually being used in the participant laboratories, we would find an even larger number still use 2sd limits as acceptability criteria. Even when you know the theory, and can recognize the practice, the pressures of generating fast results often force the capitulation of principles to production.

Zoe's website is http:www.awesome-numbers.org

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Biblioteca Digital SBPC

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Consolidação do uso de Cistatina C como marcador de função renal.

Saiu no Renal Fellow Network, o texto abaixo:


As we all know, there are significant limitations to the use of creatinine as an estimate of GFR. Creatinine is freely filtered at the glomerulus, but in addition is also secreted to some degree, meaning that creatinine clearance can overestimate GFR. Furthermore, since creatinine is produced by muscle, individuals with high muscle mass may have a calculated GFR which is low despite actually preserved renal function. Another failing of creatinine-based GFR calculations is highlighted by the ability of creatinine to predict all-cause mortality: although high creatinines are associated with a higher risk of mortality, individuals with extremely low creatinines, perhaps reflective of a poor nutritional status or low muscle mass--also show poor mortality outcomes.

In a recent article in JASN by Astor et al, the investigators provide evidence that cystatin C does a better job of predicting mortality than creatinine. Cystatin C is a cysteine protease inhibitor which is freely filtered at the glomerulus, but not secreted like creatinine is. Furthermore, cystatin C production is independent of muscle mass, making it less susceptible to the limitations of creatinine. One of the main strengths of the study is the it uses data from NHANES, which is generated from a large and ethnically diverse U.S. population with a long follow-up time; it also contains a large number of individuals with only mildly reduced GFRs in the CKD3 range. The apparent superiority of cystatin C to predict mortality and provide more accurate assessments of GFR compared to creatinine suggest it could eventually play a major role in routine lab assessment in many of our patients.