
New study says single finger-prick tests aren’t necessarily accurate - pavornyoh
http://ajcp.oxfordjournals.org/content/144/6/885.full
======
danieltillett
The article actual says that anything less than 4 drops is inaccurate for
measuring haemoglobin.

If you can’t get an accurate result measuring the most common protein in blood
then the concept is not going to go far unless you can get a few ex-generals
and war criminals on your board of directors.

~~~
petra
That's one weird thing about the theranos thing: Won't a good lab-on-a-chip
device to replace medical labs be profitable enough ? risky enough ?

Why add an extra huge risk in the form of finger pricks ? Why did Holmes and
investors even began to consider it ?

~~~
w1ntermute
What you're referring to has existed since the 90s[0].

0: [https://www.abbottpointofcare.com/products-services/istat-
ha...](https://www.abbottpointofcare.com/products-services/istat-handheld)

~~~
joezydeco
But the iStat focuses solely on clinical chemistry assays. Theranos was trying
to add microfluidic immunoassays, which is something even Abbott has been
trying to do since the first microparticle ELISA technology was invented.

------
giardini
This is no surprise whatsoever to anyone (e.g., diabetics) who uses glucose
test strips. Small sample + cheap small battery-powered measuring device =
high variation.

Is it good science? The study had a mere 11 "donors"! I know Rice is a small
school, but there are plenty of people around the university to volunteer. Its
within throwing distance of Houston's Medical Center!

~~~
gozur88
That struck me too. Not only did they have a laughably small sample size, they
didn't compare the results they got against gold-standard venous blood tests.

------
dmoy
Part of could be that it is easier to fuck up a finger prick blood draw and
cause inaccurate results. Improper cleaning [1], not getting the blood out in
the right way, or even certain patient conditions. Less likely to mess up (in
a way that causes test inaccuracy) when you drain a whole vial out of their
arm.

[1]
[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1238762/pdf/brjg...](http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1238762/pdf/brjgenprac00036-0046a.pdf)

------
robbrown451
Good. Maybe they should consider getting blood from somewhere within the 99%
of the body's surface area that doesn't have as many nerves as the tips of the
fingers.

------
geomark
I thought this has been known for quite a while. I keep seeing articles and
comments by people who have worked in this field for years saying finger-prick
blood is unreliable. I'm unclear why another study is needed.

------
nightcracker
Is it just me, or is "not necessarily accurate" just weasel words for "not
accurate"?

Either something is accurate, or it is not.

~~~
jjoonathan
You can't argue that one failure to achieve accurate results mean that it's
inherently impossible to achieve accurate results.

In this case, it's conceivable that there could be a tip geometry, tip
composition, cleaning technique, normalizing strategy, prick location/depth,
etc (or combination of the above) that leads to good data. Of course, that's
not a guarantee that it _is_ possible, and it still puts the burden of proof
on Theranos (for example) to prove that they have actually overcome this
problem if they want to run tests that way.

It _is_ mighty suggestive though.

~~~
gozur88
I don't think I'd be worried about this if I were running a company like
Theranos. There's probably still a huge market for that kind of multitest
product even if the draw was venous.

~~~
AstralStorm
And you can always draw multiple small samples, as recommended with actual
pinprick glucose meters.

Or you might be able to take smaller vials.

