Find one test method and stay with it? Pshaw

[Sheenas7]

Thank you so much Pellicle! I will read this over a few times. What is incidents per 100 patient years? Looking at the first example I see that with an INR interval of 4.5-4.9 there were 106.7 patient years, 5 events ( like bleeds) and 4.7 incidence per 100 patient years. I don't understand patient years?
Can you explain that as an example so I can understand what it means?
Also I have the mechanical St Judes mitral valve since 2001. I use the Coagucheck Vantus (model Roche sent me when I signed up last April) now it is Bio Tel because Roche sold it to them.
I am having stomach problems and not drinking any wine and eating less so I am sure it may be different next time I check. I have an appointment with the gastroenterologist. Thank you for your help every time. I really appreciate it.

One comment. What is patient years?

 

[Sheenas7]

Sheens7 - I've had to use Labcorp, too. Was the blood taken by your doctor and then picked up by Labcorp? Sometimes the blood is mishandled by the doctor's office before getting to the lab's courier.

I've found major differences between meter and lab many times.

In your case, although I'm not Pellicle, I would say that either meter is within range - I wouldn't worry too much about it. A test is considered to be 'accurate' when the value is 20% +/- the actual value. In your case, at the higher end of your result, it's accurate if it's as high as 32.6. In the case of Labcorp, the lower end of their range is 27.2.

In the case of these two measurements - accounting for the accepted variance from the test results, I'd say that you have nothing to worry about.

And the most important takeaway from this is that your INR is AT LEAST 2.7 - and probably higher, because the Labcorp test WAS higher than your meter.

Thank you Protimenow. You are right that the doctor took the sample in his office during my visit and sent it out to Labcorp. I thought the difference was a lot. Anyway one more thing to worry about.
Thank you for writing.

 

[pellicle]

One comment. What is patient years?

If you have one patient and monitor them for a year that is a patient year. If you have 2 for 6 months, that is too.

One hundred patients for a year would be one hundred patient years.

 

[Warrick]

So that means 10 patients over 10 years is 100 patient years?
Or 20 patients over 5 years?

 

[pellicle]

So that means 10 patients over 10 years is 100 patient years?
Or 20 patients over 5 years?

that's my understanding.

Just like kWh ... one kilowatt hour:

• a thousand watts in one hour
• 100 watts over 10 hours
• 2 watt over 500 hours

all gets billed the same

statistics sort of relies on the homogenisation of data, so if you have more people over a decent time you get a more meaningful data set. If you look look at the actual study again you see this:
https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/415179

We enrolled 4202 patients for a total of 7788 patient-years.​

​

We previously developed a method to determine the optimal intensity level in observational studies,10 which was subsequently applied for various indications.11-14 Some of the studies, however, were ad hoc analyses within randomized trials and could be criticized because of the small numbers of events on which the optimal intensity was based11,15 or the incompleteness of the data.12​

​

We therefore designed a large study among patients using oral anticoagulants because they had mechanical heart valve prostheses, atrial fibrillation, or had experienced a myocardial infarction. We calculated incidences of major hemorrhage and thromboembolism and assessed the optimal intensity of treatment with vitamin K antagonists by calculating international normalized ratio (INR)-specific incidence rates.​

 

[user 16827]

I love data and statistics.
i especially love a graph with a rolling average .

you need to dial into the data carefully with statistics to see the results or extrapolate the results.

if 2 people have heart surgery and one dies 50% of patients died which is a terrible statistical outcome.

obviously that is based on a small ammount of patients that is why patient years is used , it adds a layer.

 

[pellicle]

i especially love a graph with a rolling average

Me too

 

[MdaPA]

To take it a step further, the "Incidence (per 100 patient-years)" is a ratio calculated by multiplying the number of events by the incidence period then dividing that by the number of patient-years.

e.g. For the below INR Interval of 3.0-3.4, 6 X 100 / 248.8 = 2.4 Incidence (per 100 patient-years).

This means that if there were 6 events in this test group, the rate would be 6 per 248.8 patient-years or 2.4 events per 100 patient-years.

 

[Sheenas7]

If you have one patient and monitor them for a year that is a patient year. If you have 2 for 6 months, that is too.

One hundred patients for a year would be one hundred patient years.

Ok I see. Thank you.

 

[Sheenas7]

To take it a step further, the "Incidence (per 100 patient-years)" is a ratio calculated by multiplying the number of events by the incidence period then dividing that by the number of patient-years.

e.g. For the below INR Interval of 3.0-3.4, 6 X 100 / 248.8 = 2.4 Incidence (per 100 patient-years).

This means that if there were 6 events in this test group, the rate would be 6 per 248.8 patient-years or 2.4 events per 100 patient-years.

View attachment 887647

So people that tested 3.0 to 3.4 had 2.4 events in one year? Did I get that right?

 

[Sheenas7]

If you have one patient and monitor them for a year that is a patient year. If you have 2 for 6 months, that is too.

One hundred patients for a year would be one hundred patient years.

Thank you for that explanation.

 

[Amy]

So people that tested 3.0 to 3.4 had 2.4 events in one year?

They had 2.4 events over the course of 100 years.

 

[tom in MO]

Thank you for that explanation.

What did your cardiologist say about the difference in INR results?

 

[Sheenas7]

What did your cardiologist say about the difference in INR results?

He made no comment. I was asking him if I could stop the aspirin as recommended by internist due to gastro issues. He said to stop aspirin and that was it. We were talking over email. Maybe he wants an office visit to discuss further....

 

[tom in MO]

He made no comment. I was asking him if I could stop the aspirin as recommended by internist due to gastro issues. He said to stop aspirin and that was it. We were talking over email. Maybe he wants an office visit to discuss further....

If it concerns you, I'd ask him or his nurse if the gap is something of concern that needs to be addressed.

 

[Eva]

Well I had to have some blood drawn the other day and my internist used Lab Core to check my INR.
I thought it would be a good time to check the outcomes with my Vantus Xs Coagu check. I was not fasting. He took my blood at 10 am or so. I went home and an hour later my machine read 3.4. The Lab Core result came in at 2.7. I was not happy that the were .7 appart!
Is that okay? Pellicle can you comment too?

My response maybe a bit late! You may call Roche if your INR machine is from them. They will tell you what the exact difference is due to.
when my last machine gave me different results from lab, Roche called my doctor‘s office and asked them which lab they use! Roche called me back saying there should not be much difference since the lab use Roche’s same standards? My machine was old and at fault then! Just my 2-cents thoughts.

 

[pellicle]

My machine was old and at fault then! Just my 2-cents thoughts.

interesting, what was the machine (S or XS), did they ever clarify the actual fault?

 

[Protimenow]

Are you taking the 81mg Enteric coated aspirin? These shouldn't hurt your stomach - they dissolve further down (as far as I know).

 

[Sheenas7]

My response maybe a bit late! You may call Roche if your INR machine is from them. They will tell you what the exact difference is due to.
when my last machine gave me different results from lab, Roche called my doctor‘s office and asked them which lab they use! Roche called me back saying there should not be much difference since the lab use Roche’s same standards? My machine was old and at fault then! Just my 2-cents thoughts.

Thank you Eva! Roche sold to Bio Tel. I could ask Bio Tel I suppose.

 

[Sheenas7]

Are you taking the 81mg Enteric coated aspirin? These shouldn't hurt your stomach - they dissolve further down (as far as I know).

Yes 81 enteric