Shuanghe
★★  

Spain,
2014-09-10 14:17
(3486 d 21:13 ago)

Posting: # 13474
Views: 2,719
 

 number of ISR in EU [Regulatives / Guidelines]

Hi all,

I have a silly question with regard to the number of samples need for ISR according to EMA's guideline. I think it's probably more of problem of "understanding English expression".

The guideline says: "The extent of testing depends on the analyte and the study samples, and should be based upon in-depth understanding of the analytical method and analyte. However, as a guide, 10% of the samples should be reanalysed in case the number of samples is less than 1000 samples and 5% of the number of samples exceeding 1000 samples."

What I understood the phrases, with a bit common sense, is that if we have many samples in a BE study ("many" here means > 1000) then we can choose only 5% of the total samples for ISR. If we do not have that many of samples in a study ("not that many" here means < 1000) then we have to choose 10% of total samples for ISR.

However, all CROs I've worked with in India understood it as "10% of the first 1000 samples plus 5% of the remaining samples".

So if we have 2200 samples in total, my understanding is 2200x5%=110 samples for ISR but CROs will request 1000x10%+(2200-1000)x5%=160 samples.

It probably is not that important from economic perspective since the price will differ very little but this question nagged me for quite some time now I'd like to hear other forum members' opinion.

All the best,
Shuanghe
Ohlbe
★★★

France,
2014-09-10 17:27
(3486 d 18:02 ago)

@ Shuanghe
Posting: # 13476
Views: 2,243
 

 number of ISR in EU

Dear Shuanghe,

❝ However, all CROs I've worked with in India understood it as "10% of the first 1000 samples plus 5% of the remaining samples".


Their understanding is correct.

❝ So if we have 2200 samples in total, my understanding is 2200x5%=110 samples for ISR but CROs will request 1000x10%+(2200-1000)x5%=160 samples.


Let's take another example: 1200 samples in total. With your calculation you would only re-analyse 60 samples, which would be less than in a study with 900 samples in total (90 ISR samples). Would not be logical.

I agree that the wording in the guideline is not very clear... From what I know none of the authors was a native English speaker, which doesn't help :-(

Regards
Ohlbe
Shuanghe
★★  

Spain,
2014-12-19 18:19
(3386 d 16:10 ago)

@ Ohlbe
Posting: # 14120
Views: 1,809
 

 number of ISR in EU

Hi Ohlbe,

❝ Their understanding is correct.


Thanks. I noticed from some R code in one of Helmut's post as well that he also has the same understanding as the rest of you.

Now I need English class. :-D

All the best,
Shuanghe
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