Potential inconsistency of SBP between vitalsign and triage table in MIMIC-IV-ED

Prerequisites

• Put an X between the brackets on this line if you have done all of the following:
  • Checked the online documentation: https://mimic.mit.edu/
  • Checked that your issue isn't already addressed: https://github.com/MIT-LCP/mimic-code/issues?utf8=%E2%9C%93&q=

Description

Could you share more on how the vital signs in vitalsign and triage tables are recorded? I thought the vital sign in the triage table will be the first reading in vitalsign table, but after I run the following query, I realized that's not the case, so I am confused.

with temp as ( select *, rank() over (partition by stay_id order by charttime asc) as rank1 from mimic_ed.vitalsign ) select temp1.subject_id, temp1.stay_id, temp1.sbp as vitalsign_sbp, triage.sbp as triage_sbp from (select * from temp where rank1 = 1) temp1 join triage using (stay_id)

I did this check because I found that many patients have their first SBP reading recorded only after quite a while after ED intime, which looks weird to me.

Start with the MIMIC-IV-ED online documentation and compare the definitions and collection timing for the vitalsign and triage tables. Reproduce the supplied query, including the stay_id and charttime comparison, to identify why the SBP values differ. Done means documenting the relationship between the two readings and explaining the delayed first vitalsign measurement.