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MIT-LCP
WARDIDs and transfers within the ICU
I would really like to do a study that looks at the destination of patients after they leave ICU. I'm a bit confused looking at the transfers table and would like some help if possible:
To illustrate with one hospital stay:
mimic=> select icustay_id, eventtype, prev_careunit, curr_careunit, prev_wardid, curr_wardid from transfers where hadm_id = 155897;
icustay_id | eventtype | prev_careunit | curr_careunit | prev_wardid | curr_wardid
249202 | admit | | MICU | | 52
| transfer | MICU | | 52 | 32
249202 | transfer | | MICU | 32 | 52
| transfer | MICU | | 52 | 32
249202 | transfer | | MICU | 32 | 23
| discharge | MICU | | 23 |
This example brings about my first question: this particular patient has the same icustay_id throughout, but they appear to be transferred out of an ICU area twice? How does this work?
I noted some things regarding WARDIDs on your website:
- "Note that the grouping of physical locations in the hospital database is referred to as a ward. Though in practice ICUs are not referred to as wards, the hospital database technically tracks ICUs as “wards with an ICU cost center”. As a result, each ICU is associated with a WARDID, but not every WARDID is an ICU."
- "The care unit is defined based upon the ward: if the ward is an ICU cost center, then the care unit defines the type of ICU. If the ward is not an ICU then in most cases the care unit is null."
I ran some quick queries:
mimic=> select count(distinct prev_wardid) from transfers; count
53
mimic=> select count(distinct prev_wardid) from transfers where prev_careunit is null; count
42
mimic=> select count(distinct curr_wardid) from transfers where curr_careunit is null; count
40
mimic=> select count(distinct prev_wardid) from transfers where prev_careunit is not null; count
19
mimic=> select count(distinct curr_wardid) from transfers where curr_careunit is not null; count
19
To me this means that there are 53 different wards, of which 53-42=11 are always associated with an ICU cost center. A further 19-11=8 may or may not be associated with an ICU cost center (this seems slightly at odds with the second quote on there - are these patients outliers of full ICU centers?), and 53-19=34 are reliably not (ordinary wards I presume).
A classification problem with 53 output classes will be too many. I was wondering if you had any further information regarding the grouping of these wards? Particularly wards 55, 2, 45, 17, 40, 31, 18, 3, 4, 54, 24 and 36. It would be fantastic if you could tell me what these are.
Just to add to this, I've found something else that confuses me. The transfers table and the callout tables seem inconsistent to me:
mimic=> select subject_id, hadm_id, curr_careunit, curr_wardid, callout_wardid, discharge_wardid, callout_service from callout where callout_outcome = 'Discharged' limit 10; subject_id | hadm_id | curr_careunit | curr_wardid | callout_wardid | discharge_wardid | callout_service
854 | 175684 | MICU | 29 | 1 | 29 | MED
864 | 138624 | CSRU | 55 | 55 | 55 | CSURG
864 | 138624 | CSRU | 55 | 55 | 55 | CSURG
867 | 184298 | CCU | 17 | 17 | 17 | CCU
306 | 167129 | SICU | 3 | 44 | 3 | NSURG
307 | 132807 | SICU | 8 | 8 | 8 | SURG
307 | 161712 | MICU | 55 | 1 | 55 | MED
309 | 162308 | CCU | 2 | 2 | 2 | CCU
310 | 142159 | SICU | 3 | 1 | 3 | NSURG
319 | 124954 | MICU | 45 | 1 | 45 | MED
From the website:
- "CURR_WARDID identifies the ward in which the patient resides when called out (i.e. prior to discharge/transfer). CURR_CAREUNIT indicates which ICU cost center the CURR_WARDID corresponds to (note: since all patients are being discharged from an ICU, all patients should reside in an ICU cost center)."
But in the transfers table, all of these wards are never associated with an ICU care center:
select distinct curr_wardid, curr_careunit, count(distinct row_id) from transfers group by curr_wardid, curr_careunit order by curr_wardid; curr_wardid | curr_careunit | count
2 | | 9345
3 | | 5775
4 | | 4505
5 | NWARD | 4376
6 | | 51
7 | CCU | 6837
7 | | 548
8 | | 1295
9 | | 865
10 | | 29
11 | | 3
12 | CSRU | 3529
12 | MICU | 2181
12 | | 1
13 | | 23
14 | CSRU | 3809
14 | SICU | 609
14 | TSICU | 6051
15 | CSRU | 4696
15 | MICU | 2750
15 | | 2
16 | MICU | 156
17 | | 9149
18 | | 5412
19 | | 2
20 | | 5
22 | SICU | 58
23 | CSRU | 1120
23 | MICU | 5601
23 | SICU | 1068
23 | TSICU | 664
23 | | 5
24 | | 3147
25 | | 79
26 | NICU | 1200
27 | | 7011
28 | | 1192
29 | | 2212
30 | | 187
31 | | 6207
32 | | 2960
33 | CSRU | 442
33 | SICU | 5123
33 | TSICU | 1382
33 | | 5
34 | | 52
35 | | 25
36 | | 4689
37 | CCU | 81
38 | MICU | 71
39 | | 25
40 | | 7019
41 | | 84
42 | NICU | 93
43 | NWARD | 3919
44 | | 20
45 | | 8529
47 | CSRU | 67
48 | | 1864
49 | | 7624
50 | MICU | 5276
51 | | 183
52 | MICU | 10365
52 | | 47
54 | | 4690
55 | | 12072
56 | NICU | 17336
57 | CCU | 2624
57 | SICU | 4465
57 | TSICU | 67
| | 58943
The curr_wardid is almost always the same as the discharge_wardid unless the patient is going home. Has the curr_wardid in the callout table been mislabelled?
This example brings about my first question: this particular patient has the same icustay_id throughout, but they appear to be transferred out of an ICU area twice? How does this work?
Apologies for the delay in responding to your issue. Regarding this first question, based on the _careunit variables it doesn't look like they are transferred outside of the MICU. The _wardid variables represent a physical location within the hospital but not necessarily what care is being provided in that location.
The curr_wardid is almost always the same as the discharge_wardid unless the patient is going home. Has the curr_wardid in the callout table been mislabelled?
I'm not sure if I fully understand what you are asking here. I'd expect there would be overlap between the curr_wardid and discharge_wardid, especially when curr_wardid is an ICU.
