Does data change between versions of mimic III database?

Question

I am on version 1.4 and the query below which is suppose to count number of in-hospital mortalities has a count of 5854. However, I'm reading a paper that is written on version 1.3 of mimic III and claims that there are 5813 in-hospital mortality events.

SELECT count(*) FROM ADMISSIONS 
WHERE DEATHTIME IS NOT NULL ORDER BY DEATHTIME;

Either my query is wrong or does the data change between v 1.3 and v 1.4 of mimic iii?

Answer 1

Several changes are made between versions, some of which may affect the result to queries such as the one in your question. A summary of the changes is listed on the MIMIC website: http://mimic.physionet.org/about/releasenotes/

In this particular case however it looks like the difference is a result of your query double counting 41 subject_ids. Adding the DISTINCT keyword to your query returns 5813 uniquesubject_id in MIMIC-III v1.4.

SELECT COUNT(DISTINCT subject_id)
FROM admissions
WHERE deathtime IS NOT NULL;


 count 
-------
  5813
(1 row)

I believe the duplicates relate to the way organ donor accounts are recorded in the system (see the diagnosis column of the admissions table).