# Differences in number of unique drugs per clinical precedence

**URL:** <https://community.opentargets.org/t/differences-in-number-of-unique-drugs-per-clinical-precedence/1080>\
**Category:** Data Access\
**Created:** [15 May 2023 14:02 UTC](https://community.opentargets.org/t/differences-in-number-of-unique-drugs-per-clinical-precedence/1080 "2023-05-15T14:02:57Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![Karl\_Gemayel](https://dub1.discourse-cdn.com/flex017/user_avatar/community.opentargets.org/karl_gemayel/32/423_2.png) [@Karl\_Gemayel](https://community.opentargets.org/u/Karl_Gemayel)\
**Post date:** [15 May 2023 14:02 UTC](https://community.opentargets.org/t/differences-in-number-of-unique-drugs-per-clinical-precedence/1080/1 "2023-05-15T14:02:57Z")

</div>

I’m trying to get a dataframe with all clinical data using the json/parquet files. Specifically, I care about drugId, targetId, diseaseId, and maxPhaseForIndication.

It seems this data is present in ‘molecule’, ‘indication’, and ‘knownDrugsAggregated’ files. However, the numbers I get from each are very different.

Can someone explain why? And perhaps suggest the best way to get this information?

---

<div class="post-metadata">

**Author:** ![irene](https://dub1.discourse-cdn.com/flex017/user_avatar/community.opentargets.org/irene/32/50_2.png) [@irene](https://community.opentargets.org/u/irene)\
**Post date:** [16 May 2023 16:03 UTC](https://community.opentargets.org/t/differences-in-number-of-unique-drugs-per-clinical-precedence/1080/2 "2023-05-16T16:03:15Z")

</div>

Hi @Karl_Gemayel and welcome to our Community!

In your case I would use the evidence parquet file, it should be straightforward to extract a dataframe with the fields that you need directly from there. You wouldn’t need to perform any joins.

As you know, ChEMBL is a provider of evidence between target and disease. ChEMBL evidence represents any target-disease relationship that can be explained by an approved or clinical candidate drug, targeting the gene product and indicated for the disease.

If you download [ChEMBL evidence](http://ftp.ebi.ac.uk/pub/databases/opentargets/platform/latest/output/etl/parquet//evidence/sourceId=chembl/), your fields of interest are: `drugId`, `clinicalPhase`, `targetId`, `diseaseId`. Note that one evidence represents one study, so to extract the max phase for indication you’d need to aggregate the data and extract the maximum clinical phase. I hope this is helpful.

Could you please elaborate on the differences in numbers you are seeing?

Best,  
Irene