CSF UPENN analyses

[Konstantinos Chiotis]

Hello,

I had one short question with regards to the CSF biomarkers from UPENN.

I have understood that during the ADNIs different phases the CSF samples were analyzed at different batches and with different assays. The most recent data are analyzed with the Elecsys assay.

My question concerns the master csv file UPENNBIOMK_MASTER_FINAL.

In the file there are ABETA42, PTAU and ABETA_RAW, PTAU_RAW values among others. If I understand correctly the ABETA42 and PTAU values are values that should be consistent across batches or at least all values are rescaled to the Elecsys assay values. Is it like this or have I misunderstood?

Many thanks

K

[Danielle J Harvey]

Hello,

 

If you look at the BATCH variable, UPENNBIOMK-UPENNBIOMK8 are from the original assay, while UPENNBIOMK9-UPENNBIOMK13 are with Roche Elecsys. Most of the available samples were rerun with the Roche Elecsys assay, so you should still have most samples if you restrict your attention to BATCH in UPENNBIOMK9, UPENNBIOMK10, UPENNBIOMK12, and UPENNBIOMK13. I am not aware of the original assay being bridged to the Roche Elecsys assay, so it is safer to always work with values generated from the same assay…

 

Another thing to note about this file is that there are multiple rows for the same RID/VISCODE combination (typically from different batches). The Biomarker Core typically recommends that if you are just using the initial visit for each person, you should take the value from the earliest UPENNBIOMK file (so for example, if the initial visit is in UPENNBIOMK9 and UPENNBIOMK10, take the value from UPENNBIOMK9). If you are interested in longitudinal values, for each person, use the file that has the most assessments (so it is not recommended to use different BATCH within the same person).

 

Danielle

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[Konstantinos Chiotis]

Many thanks :)