About SNOMED CT
• 40 year old medical terminology
– 322,544 concepts (and growing)
Growth of SNOMED
388,289
(Jul 2009)
400,000
(Apr 2012)
International Core
+ UK national extensions
+ DM+D
(+ US drug extensions)
350,000
368,590 (Jan 2006)
SNOMED
357,135 (Jan 2004)
SNOMED CT R1
325,856 (Jan 2002)
300,000
Total: 709,742 concepts
(of which 504,084 active)
1,199,678 ‘en’ descriptions
250,000
262,231
Oct 2004
Concepts
SNOMED RT (Beta)
200,000
SNOMED International
150,000
(V 3.1)
(V 3.2)
100,000
(V 3.0)
SNOMED II
50,000
(V 3.4)
395,346
(Apr 2012)
378,111 (Jan 2008)
237,557
Oct 1999
249,081
Mar 2002
270,600
Apr 2006
308,032
282,253
292,524 (Apr 2012)
Apr 2008
(Oct 2009)
CTV3
(V 3.5)
(V 3.3)
81,885
Sep 1999
83,076
Oct 2001
85,647 86,865
Oct 2003 Jul 2004
90,956
Apr 2007
93,717
(Oct 2009)
95,832
(Apr 2012)
READ2
37,502 (Jan 1991)
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012
• Attempting an ‘in situ’ migration to EL+
– And ‘seamless’ deployment into an industry
based on enumerated classifications
– 18-country international effort, $9.3M annually
SNOMED CT in UK
• Many secondary care sites
– Some primary care
•
•
•
•
13,353,775 Summary Care Records
33M Choose & Book referrals
Electronic TFR of prescriptions
Soon: Radiology & Pathology messaging
Issues
• Change management
– Migration from/integration with legacy systems
– Changes in SNOMED CT itself
– Death by 1,000 mutual dependencies
• Implementation skills
• User interfaces (or, data repair)
• Tools
– Time to load & classify
– Content refactoring
– ‘Linkage’ to external resources
• Business case
SNOMED CT
39 months @ a busy UK A&E Department
• One ‘reason for encounter’ code per
completed visit
– 408,823 coded episodes
•
•
•
•
39 months (Oct 2008 – Dec 2011)
12,323 distinct codes selected at least once
8,387 not coded (or uncodable?) = 1 in 50 episodes
20-50% miscoding rate
Relative code use
20000
1000 distinct SNOMED CT codes
account for 84% of the data
18000
16000
Top 15 tunes…(22.8% of all episodes)
18332 282026002|Soft tissue injury (disorder)
13995 21522001|Abdominal pain (finding)
10588 82271004|Injury of head (disorder)
9466 29857009|Chest pain (finding)
6861 213257006|Generally unwell (finding)
6113 367391008|Malaise (finding)
4656 161891005|Backache (finding)
4435 44465007|Sprain of ankle (disorder)
4309 34014006|Viral disease (disorder)
3777 399221001|Bleeding from vagina (disorder)
2871 35933005|Laceration (morphologic abnormality)
2690 281794004|Viral upper respiratory tract infection (disorder)
2622 68566005|Urinary tract infectious disease (disorder)
2404 19130008|Traumatic abnormality (morphologic abnormality)
2280 281245003|Musculoskeletal chest pain (finding)
14000
12000
10000
8000
6000
4000
2000
0
1
1001
2001
3001
4001
5001
6001
7001
8001
9001
10001
11001
12001
7.8% ‘Ontology-driven’ miscoding…
(disorder)
234693
(finding)
123430
(procedure)
6583
(situation)
6379
(event)
4592
(regime/therapy)
1344
TOTALS
377021
(morphologic abnormality)
(qualifier value)
(body structure)
(substance)
(attribute)
(observable entity)
(physical object)
(product)
(cell)
(navigational concept)
(organism)
(physical force)
(record artifact)
(ethnic group)
(environment)
(assessment scale)
(person)
(specimen)
(administrative concept)
(tumor staging)
(social concept)
(cell structure)
(occupation)
(inactive concept)
17024
4544
3517
2340
1293
1139
746
233
226
206
199
152
97
17
15
14
10
9
6
5
4
3
2
1
31802
Miscoding examples
1097
17
373
136
82
78
Temperature
Drug used
ETOH - Alcohol intake
Nasogastric tube
Catheter
Dressing
246508008|Temperature (attribute)|
246488008|Drug used (attribute)|
160573003|Alcohol intake (observable entity)|
17102003|Nasogastric tube, device (physical object)|
19923001|Catheter, device (physical object)|
37898001|Dressing, device (physical object)|
110
83
43
53570002|Removal of foreign body from eye (procedure)|
172828005|Removal of foreign body from nose (procedure)|
172278002|Removal of foreign body from eyelid (procedure)|
293
166
7
82576008|Retained foreign body in eye (disorder)|
74699008|Foreign body in nose (disorder)
25012008|Retained foreign body of eyelid (disorder)|
Variable Data Quality
• 23% of 74 abdominal aortic aneurysms miscoded as a Drug Trade
Family (9192101000001100 AAA (product)); AAA make sore throat
spray(and not much else)
• 25% of 939 stabbing victims miscoded as a qualifier value (‘stabbing
sensation quality’, as in heart attack)
• 33% of 3771 patients with some form of high temperature miscoded
as either an attribute, or a physical force
• 38% of 1101 failed consultations (patient left the department, or did
not attend an appointment) miscoded as either a laterality (left) or as
deoxyribonucleic acid (DNA = Did Not Attend)
• 44% of 575 patient attending with a fish bone stuck in their throat
miscoded as the bone itself (7661006|Fish bone (substance)|)
• 49% of 5,062 alcohol-related attendances miscoded as either the
substance (alcohol, ethyl alcohol) or just feeling elated/intoxicated
but not necessarily involving alcohol intake at all
Not all bad news:
Admissions for sickle cell
• Clinical impression
– ‘They stop coming once they get older; most of the
attendances will be in the 15-20 age group’
• Clinical lore
– Cold weather triggers attacks
‘People with sickle cell disease should try to avoid any potential triggers for a sickle cell crisis as much a
possible. For example: try to keep warm in cold weather, try to avoid becoming dehydrated and take
precautions if you undergo extreme exercise’
(patient.co.uk)
• Clinical Data…???
60
50
AGE at presentation vs DATE of presentation
60 day average, rolling count of attendances in last 14 days
1336 A&E attendances, 410 patients
Completed episodes October 2008 thru December 2011
Reason for attendance: sickle cell
But:
We could probably have got this particular result using ICD.
Overall, is the ontology (as implemented) helping or hindering
primary data capture and secondary data analysis?
WINTER 2011-12
70
WINTER 2008-9
80
40
30
20
10
0
Sunday, June 1, 2008
Monday, June 1, 2009
Tuesday, June 1, 2010
Wednesday, June 1, 2011
Thursday, May 31, 2012