Sunday, July 3, 2016

Would a finger prick with each pediatric visit make sense?

The Internet and social networks are huge amplifiers. T1D communities, once you get to know them, are among the worst offenders... When they aren't busy lynching restaurant owners for signs asking diabetic patients no to inject themselves in public or attacking some minor public person who confused T2D with T1D, they busy themselves with a "fingerpricks for every kid" crusade.

Does that idea even remotely make sense? Here is some food for thought...

Using 2009 figures, around 30.000 persons were diagnosed with diabetes in the USA. A ballpark estimate is that out of those 30.000 patients, 2/3rd are under the age of 20. This matches the official tally that was, for that period

"During 2008–2009, an estimated 18,436 people younger than 20 years in the United States were newly diagnosed with type 1 diabetes annually..."

Severe DKA is generally present, on average, in 25% of those patients. The percentage can go as high as 50% for kids in the 0-4 yo range, is a bit lower in girls than in boys and, of course, varies with care accessibility, insurance coverage, education level, etc...

Let's say that 4750 of the 18436 patients above were in severe DKA (as opposed to mild, safely correctable DKA which is probably present in another 25%)

The approximate rate of death and extremely severe complications from DKA is between 5 and 2% depending again on socio economic and access issues. If we take a value of 3%, we end up with around 150 tragic deaths per year.

Yes, the rate of T1D diagnosis has increased, US is closer to 40.000 yearly diagnosis now. But, on the other hand, death by DKA has been on the decrease since a long time. Yes, improvements are also made there;

"from 1985 to 2002, age-adjusted death rates for hyperglycemic crisis decreased from 42.4 to 23.8 per 100,000 people with diabetes, a 4.4% decrease per year"

Total yearly deaths by DKA (all ages, all causes) seem to hover in the 2500 range. Going back to our earlier estimate, we'd end up with 150 yearly deaths around diagnosis and 2350 yearly DKA deaths during the rest of the life or a T1D (pump failures, not caring, no access, etc...)

Keep in mind that out of those 150 deaths, we have parents who simply "prayed" their kid would get better, parents who weren't covered by social security and were reluctant to see a doctor, kids who fell into DKA and were correctly and immediately diagnosed and some - which could be seen as the "misdiagnosed" and "problematic" ones. It is hard to say how many, but it is nonetheless a subset of 150.

I'll be very generous and use the following split: 50 did not see a doctor soon enough, 50 did and were immediately diagnosed, 50 did and some mistake occurred. Let's say that the doctor flipped a coin in all cases. I think we can assume this as a worst case scenario.

Would a finger prick avoid any of those 50 deaths?

How quickly does DKA develop? In our case, Max was playing a game of tennis against as stronger adult player on day minus one. He lost 6-4 6-4, hardly a severe beating. He wasn't looking his best, but still spent time chatting and drinking a coke with his opponent after the game. The following day, he was on the edge of consciousness...

The clinical presentation of DKA usually develops rapidly, over a period of  less than 24 hours.<24 hours="" i="">

Ah, that's a bit annoying... It could be that a finger prick done a week before would have shown elevated by not critical blood sugar values, that would have been hard to interpret if not done after a night of fast. Type 1? Type 2? Post meal?

There's a reason why diagnosis criteria for T2D require at least a couple of venous blood values in the fasting state...

Now, people who complain about finger prick tests not being systematically done with every pediatric visit are often people who complain about their BG meter being inaccurate. Logically, a single test shouldn't be taken at face value. Anyway, maybe they just like to complain...

How many finger pricks?

The under twenty population of the USA is around 80.000.000. The average American, all ages groups, sees a doctor 3 times a year (900.000.000 yearly visits). That's low compared to countries such as Japan (13 times a year) or France (6-7 times a year) and has been linked to the cost of care in the US.

We can also assume that kids in the 0-20 range see their doctors more than the average. I will be very conservative here and estimate that they have 4 visits per year on average. We "only" have 320.000.000 of visits to deal with. Assuming 1/2 of those visits are for the typical gastro-intestinal/infection/flu/etc... pediatric visit, we are talking about 160.000.000 visits and probably a bit more than 200.000.000$ in finger prick strips.

That 200.000.000$ would eventually buy us a few hours, possibly a day for the 50 kids who would have been misdiagnosed at the first visit, possibly - let's again be generous here - saving 25 kids.

Cost per kid saved: roughly 8 million dollars.

But the story does not end here...

Let's say that those 25 kids in the 250-500 mg/dl - something is definitely wrong here - ranges are "saved". What about the vast majority of the others, in the 100 mg/dl to 250 mg/dl range? Those would of course end up being investigated further. Hard to tell if they were fasting, just had a large ice cream, are pre T2D or T2D. More visits. More tests.

And what about false positives? A decent BG meter will perform, on average, within a +/-5% to +/-7% MARD but will have occasional outliers (because of strip issues, procedural issues or just bad luck). Let's assume that we only have one outlier out of 50 measurements, one half way too low and on half way too high: we'll have 3.2 millions outliers and 1.6 millions of false positive values.

So let's summarize

  • around 25 lives saved, at most.
  • 8 millions of $ per life saved, for a total of 200 millions of dollars
  • 1.6 millions of false positive deserving at least a couple of additional tests/visits or, because mistakes will also happen there, extensive additional exploration.

Worth it? 

1 comment:

  1. Our son had a fasting BG of ~72 on the day he was diagnosed...he got to 500 after a snack...and he had had normal-low fasting BGs at previous tests that we had asked our doctor to do (we had been telling our doctor something was off for 6 months). I don't know if it's because fasting was more like 12 hours from his bedtime (2 years old) to the time of check or what, but fasting BGs were never elevated. So, I agree that a BG check is near-worthless.

    In our case, finding sugar in the urine was more reliable and an A1C would have been the best check. BG checks, as you are saying, only give a short glimpse into "right now" and that's not worth it. An A1C test, once a year until someone is found to be pre-diabetic, then at least twice a year recommended after pre-diabetic diagnosis???

    I don't know how reliable this would be...but if doctors were trained to watch and ask for: "does your toddler blow out their diaper EVERY night and have extremely heavy diapers in the morning even if you don't give them a lot to drink at bedtime," or "has your child's frequency of drinking or urination increased noticeably recently?" (and maybe some other symptoms if any) and if the answer is an A1C. We had been telling our doctor this for 6 months and he just kept blowing us off...this is the issue that I would like to resolve...better training for pediatricians to do "early rule outs" when they see something that "might be" diabetes...because as far as things to rule out, this is a pretty cheap disease to rule out.