New Glucose Standards – based on medical requirements?

March 14, 2012

Two new glucose meter standards are nearing completion: CLSI POCT 12 for hospital based glucose meters and ISO 15197 for home use glucose meters. The current versions of these standards use the same performance specification – the CLSI standard defaults to the ISO standard.

The latest drafts of the new standards have tighter performance limits. The current ISO standard states that performance limits are based on medical acceptability. This sounds good and who can argue with that. But one can ask, has medical acceptability in diabetes changed this much in 10 years to warrant tighter performance limits? Another possible explanation for the spec change is that performance limits are based on glucose meter performance capability and this capability has improved.

To base standards on the performance capability of an assay is not so strange. The 510(k) process uses the principle of a candidate assay’s performance being substantially equivalent to a predicate assay.

Moreover, medical acceptability is a difficult concept. One could argue that patient harm increases with increasing assay error and the only condition that is benign is the case of no error. So it is difficult to draw a line which would equate patient harm as being medically acceptable.

Assay error occurs so there will always be some patient harm but the alternative – to keep an assay off the market and prevent clinicians from obtaining the information that the assay provides will invariably be more harmful than patient harm from assay error.

So the basis of a spec to set limits according to the performance capability of existing assays makes sense. And it is not based on medical acceptability.

Finding a coach in clinical chemistry

March 2, 2012

I was inspired by a New Yorker article by Atul Gawande, which is here. As a practicing surgeon, Dr. Gawande wanted someone to advise him on how he was doing. He had previously had a coaching experience in tennis, which happened by chance. He did engage a retired surgeon to coach him and I suggest you read the article.

I took up snowboarding a few years ago and while I seemed to do everything right, I had trouble on steeper hills. I finally hired an instructor who said, “you’re not leaning forward enough” and the problem was solved.

With my pilot’s license, I can legally fly whenever I want but some of my landings were not very good. I had to convince myself that it was ok to ask for help and then it was easy to hire an instructor to help me since I rent from a flight school – “lower the nose, don’t turn final until you see the PAPI”.

As a private pilot, “whenever” assumes that the weather meets certain minimums, I have had a flight review within two years, and that if I want to take passengers, I have had three take-offs and landings within 90 days. Thus, there are conditions to exercise the privilege and an attempt to evaluate proficiency. If one is a board certified clinical chemist, I am unaware of any type of proficiency check.

When I first started at Technicon Instruments, I had two coaches – Dr. Stan Bauer and Cuthbert Daniel. Both helped me a lot. I have also taken courses over the years, many of which helped. Writing papers (especially with coauthors) and preparing laboratory standards (CLSI) has also been helpful.

Now as an independent statistical consultant, finding someone to coach me is not easy. But I’m looking.