Crohn’s Disease Algorithm Case Definitions, Characteristics of Validation Studies for Each Definition, and Studies Citing the Definition.
| Definition . | Specific Definition and Diagnostic Accuracy . | Characteristics of Validation Study . | Reference . |
|---|---|---|---|
| ≥1 ICD diagnosis code | ≥1 ICD-8 563.0 or ICD-9 555.x code during hospitalization No mention of exclusions PPV 87% | United Kingdom Barton 1989 Validation years: 1968-1983 Inpatient only No minimum follow-up Pediatric (≤20 y) | 37 |
| ≥1 ICD diagnosis code | ≥1 ICD-8 563.01 during hospitalization If 563.19 or 569.04 then exclude Sensitivity 94% | Denmark Fonager 1996 Validation years: 1988-1992 Inpatient only No minimum follow-up No age restriction | 58 |
| ≥1 ICD diagnosis code | ≥1 ICD-9 555.x during hospitalization If 556.x then exclude Sensitivity 82% | Italy Di Domenicantonio 2014 Validation years: 2000-2009 Inpatient only No minimum follow-up No age restriction | 18 |
| ≥1 ICD diagnosis code | ≥1 ICD-9 555.x in inpatient or outpatient setting No mention of exclusions PPV 18%-67% | United States Herrinton 2007 Validation years: 1999-2001 Inpatient or outpatient No minimum follow-up No age restriction | 45 |
| ≥1 ICD diagnosis code | ≥1 ICD-9 555.x in inpatient or outpatient setting No mention of exclusions Sensitivity 83% PPV 74%-82% | United States Herrinton 2008 Validation years: 1996-2002 Inpatient or outpatient ≥12 mo of enrollment No age restriction | 55 |
| ≥1 ICD diagnosis code | ≥1 ICD-9 555.0, 555.1, 555.2 or 555.9 in inpatient or outpatient setting No mention of exclusions for UC. Excluded unspecified intestinal obstruction (560.9). Sensitivity 92% Specificity 99% PPV 88% NPV 99% | United States Thirumurthi 2010 Validation years: 2000-2004 Inpatient or outpatient No minimum follow-up Adults (military veterans) | 34 |
| ≥1 ICD diagnosis code | ≥1 ICD-10 K50.x as primary diagnosis during hospitalization No mention of exclusions Sensitivity 98% NPV 99% | Canada Stepaniuk 2015 Validation years: 2007-2012 Inpatient only No minimum follow-up Adults (≥65 y) | 8 |
| ≥1 ICD diagnosis code | ≥1 ICD-10 K50.0, K50.1 or K50.8 during hospitalization If K51.x then exclude Sensitivity 30%-95% Specificity 89%-99% PPV 67%-97% NPV 66%-99% | Canada Ma 2017 Validation year: 2011 Inpatient only No minimum follow-up Adults (≥18 y) | 44 |
| ≥1 ICD diagnosis code | ≥1 ICD-10-CM code No mention of exclusions Sensitivity: 95% Specificity: 93% PPV: 91% NPV: 97% | Denmark Lo 2020 Validation years: 2003-2011 Inpatient and outpatient No minimum follow-up No age restriction | 1 |
| ≥1 ICD diagnosis code and prescription | ≥1 ICD-10-CM K50.x code with 0 K51.x and 0 M35.x and ≥1 medication If K51.x or M35.x then exclude Sensitivity: 100% Specificity: 99% PPV: 97% NPV: 100% | Japan Morikubo 2021 Validation years: 2015-2019 Inpatient and Outpatient No minimum follow-up No age restriction | 0 |
| ≥1 ICD diagnosis code | ≥1 OXMIS/Read code 5630CR, 5630C, 5630ER, 0092LR in primary care records If 5631 then exclude Sensitivity 94% | United Kingdom Lewis 2002 Validation year: 1988-1997 Primary care only No minimum follow-up No age restrictions | 46 |
| ≥1 ICD diagnosis code and ≥1 prescription | ≥1 ICD-9 555.x in electronic health record AND ≥1 mention of 5-aminosalicylate, antibiotic, corticosteroid, immunomodulator, anti-TNF or natalizumab Excluded if had code for rheumatoid arthritis (714.x) or multiple sclerosis (340, 341.9, 323.9). Determined CD vs UC based on proportion. PPV 100% | United States Restrepo 2016 Validation years: Not reported Electronic health record (presumably inpatient or outpatient) No minimum follow-up No age restriction | 6 |
| ≥1 ICD diagnosis code and ≥1 prescription | ≥1 code and recorded in the SWIBREG Quality Register and received a biologic No mention of exclusions Sensitivity: 90% Specificity: 96% PPV: 97% | Sweden Shrestha 2020 Validation years: 1999-2017 Included in Register No minimum follow-up No age restriction | 3 |
| ≥1 ICD diagnosis code and ≥1 prescription | ≥1 ICD-10 K50.x code and ≥1 prescription for 5-aminosalicylate, immunomodulator, anti-TNF No mention of exclusions Sensitivity: 98% Specificity: 98% PPV: 98% NPV: 98% | South Korea Lee 2019 Validation year: 2011 Inpatient or outpatient No minimum follow-up No age restriction | 6 |
| ≥1 ICD diagnosis code and ≥1 prescription and met criteria for diagnosis based on NLP algorithm | ≥1 ICD-9 555.x in inpatient or outpatient setting AND ≥1 electronic prescription for 5-aminosalicylate, corticosteroids, immunomodulator or anti-TNF AND NLP definition met No mention of exclusions Sensitivity 69%-72% Specificity 97% PPV 98% AUC 0.95 | United States Ananthakrishnan 2013 Liao 2015 Validation years: Not reported Inpatient or outpatient No minimum follow-up No age restriction | 75 & 98 |
| ≥1 ICD diagnosis code and included in registry | ≥1 ICD-10 K50.x in inpatient or outpatient setting AND registered in rare disease database as Crohn’s disease (RID V130) No mention of exclusions Sensitivity 94.5%-98.3% Specificity 93.5% | South Korea Soh 2019 validated 2010-2013 Park 2018 validated 2010-2013 Kim 2015 validated 2006-2012 Inpatient or outpatient No minimum follow-up No age restriction | 10 & 19 & 58 |
| ≥1 ICD diagnosis code and included in registry | ≥1 ICD-7 572.00, 572.09; ICD-8 563.00; ICD-9 555.x; or ICD-10 K50.x code in inpatient or outpatient specialty visit AND registered at least once in a national IBD registry Mixed CD and UC codes considered IBD-U PPV 90% | Sweden Jakobsson 2017 Validation years: 1987-2015 Inpatient or outpatient specialty visit No minimum follow-up No age restriction | 28 |
| ≥2 diagnosis codes | ≥2 ICD-9 555.x codes with ≥1 outpatient If 556.x then exclude PPV 84% | United States Hou 2014 Validation years: 1999-2009 Inpatient or outpatient No minimum follow-up Adults (military veterans) | 35 |
| ≥2 diagnosis codes | ≥2 ICD-9-CM 555.x codes with ≥1 colonoscopy on same date as a 555.x code If 556.x then exclude Sensitivity: 49% Specificity: 88% PPV: 81% | United States Singla 2020 Validation years: 1996-2012 Inpatient or outpatient 3-y minimum follow-up Adults (active duty military) | 1 |
| ≥3 diagnosis codes | ≥3 ICD-9-CM 555.x codes from a gastroenterologist or surgeon If 556.x or 558.x then exclude Sensitivity: 71% Specificity: 86% PPV: 84% | United States Limketkai 2019 Validation years: 1998-2011 Inpatient or outpatient 3-y minimum follow-up Adults (active duty military) | 2 |
| ≥2 ICD diagnosis codes | ≥2 ICD-9 555.x in inpatient or outpatient setting No mention of exclusions Sensitivity 82% PPV 88% | United States Liu 2009 Validation years: 1996-2002 Inpatient or outpatient ≥12 mo of enrollment No age restriction | 21 |
| ≥3 diagnosis codes | ≥3 ICD-8 563.x or ICD-10 K50.x in inpatient or outpatient setting No mention of exclusions PPV: 75% | Denmark Rye 2021 Validation years: 1998-2015 Inpatient or outpatient No minimum follow-up Age ≥50 y | 0 |
| Number of ICD encounters within a time period | ≥2 hospitalizations or ≥4 physician claims or ≥2 ambulatory surgery visits for ICD-9 555.x or ICD-10 K50.x within 2 y Used number of CD visits among IBD visits to distinguish CD from UC Sensitivity: 94% Specificity: 99% | Canada Rezaie 2012 Validation years: 1997-2007 Inpatient or outpatient No minimum follow-up No age restriction | 24 |
| Number of ICD encounters within a time period | ≥9 ICD-9 555.x or 556.x or ICD-10 K50.x or K51.x. 5/9 of the most recent visits must be for CD (ICD-9 555.x or ICD-10 K50.x). All 9 codes must occur within a 4-y period. Accuracy 95.6% | Canada Benchimol 2014 Validation years: 2001-2006 Inpatient or outpatient No minimum follow-up Adults (≥18 y) | 58 |
| Number of ICD encounters within a time period | ≥7 IBD physician visits: ≥5 of last 7 coded for CD (555.x, K50.x) <7 IBD physician visits: All visits for ICD-9 555.x or ICD-10 K50.x All visits within a 3-y period. Sensitivity: 95% Specificity: 86% PPV: 92% NPV: 91% | Canada Benchimol 2009 Validation years: 2001-2005 Outpatient No minimum follow-up Pediatric (<18 y) | 109 |
| Number of ICD encounters within a time period | For residents of the province for ≥2 years: ≥5 outpatient encounters or hospitalizations for ICD-9 555.x or 556.x For residents of the province for <2 years: ≥3 outpatient encounters or hospitalizations for ICD-9 555.x or 556.x If a combination of CD and UC codes observed, required at least 9 codes. If majority of 9 most recent codes are 555.x then CD. Sensitivity 89% Specificity 90% | Canada Bernstein 1999 Validation years: 1984-1995 Inpatient or outpatient No minimum follow-up No age restriction | 147 |
| Definition . | Specific Definition and Diagnostic Accuracy . | Characteristics of Validation Study . | Reference . |
|---|---|---|---|
| ≥1 ICD diagnosis code | ≥1 ICD-8 563.0 or ICD-9 555.x code during hospitalization No mention of exclusions PPV 87% | United Kingdom Barton 1989 Validation years: 1968-1983 Inpatient only No minimum follow-up Pediatric (≤20 y) | 37 |
| ≥1 ICD diagnosis code | ≥1 ICD-8 563.01 during hospitalization If 563.19 or 569.04 then exclude Sensitivity 94% | Denmark Fonager 1996 Validation years: 1988-1992 Inpatient only No minimum follow-up No age restriction | 58 |
| ≥1 ICD diagnosis code | ≥1 ICD-9 555.x during hospitalization If 556.x then exclude Sensitivity 82% | Italy Di Domenicantonio 2014 Validation years: 2000-2009 Inpatient only No minimum follow-up No age restriction | 18 |
| ≥1 ICD diagnosis code | ≥1 ICD-9 555.x in inpatient or outpatient setting No mention of exclusions PPV 18%-67% | United States Herrinton 2007 Validation years: 1999-2001 Inpatient or outpatient No minimum follow-up No age restriction | 45 |
| ≥1 ICD diagnosis code | ≥1 ICD-9 555.x in inpatient or outpatient setting No mention of exclusions Sensitivity 83% PPV 74%-82% | United States Herrinton 2008 Validation years: 1996-2002 Inpatient or outpatient ≥12 mo of enrollment No age restriction | 55 |
| ≥1 ICD diagnosis code | ≥1 ICD-9 555.0, 555.1, 555.2 or 555.9 in inpatient or outpatient setting No mention of exclusions for UC. Excluded unspecified intestinal obstruction (560.9). Sensitivity 92% Specificity 99% PPV 88% NPV 99% | United States Thirumurthi 2010 Validation years: 2000-2004 Inpatient or outpatient No minimum follow-up Adults (military veterans) | 34 |
| ≥1 ICD diagnosis code | ≥1 ICD-10 K50.x as primary diagnosis during hospitalization No mention of exclusions Sensitivity 98% NPV 99% | Canada Stepaniuk 2015 Validation years: 2007-2012 Inpatient only No minimum follow-up Adults (≥65 y) | 8 |
| ≥1 ICD diagnosis code | ≥1 ICD-10 K50.0, K50.1 or K50.8 during hospitalization If K51.x then exclude Sensitivity 30%-95% Specificity 89%-99% PPV 67%-97% NPV 66%-99% | Canada Ma 2017 Validation year: 2011 Inpatient only No minimum follow-up Adults (≥18 y) | 44 |
| ≥1 ICD diagnosis code | ≥1 ICD-10-CM code No mention of exclusions Sensitivity: 95% Specificity: 93% PPV: 91% NPV: 97% | Denmark Lo 2020 Validation years: 2003-2011 Inpatient and outpatient No minimum follow-up No age restriction | 1 |
| ≥1 ICD diagnosis code and prescription | ≥1 ICD-10-CM K50.x code with 0 K51.x and 0 M35.x and ≥1 medication If K51.x or M35.x then exclude Sensitivity: 100% Specificity: 99% PPV: 97% NPV: 100% | Japan Morikubo 2021 Validation years: 2015-2019 Inpatient and Outpatient No minimum follow-up No age restriction | 0 |
| ≥1 ICD diagnosis code | ≥1 OXMIS/Read code 5630CR, 5630C, 5630ER, 0092LR in primary care records If 5631 then exclude Sensitivity 94% | United Kingdom Lewis 2002 Validation year: 1988-1997 Primary care only No minimum follow-up No age restrictions | 46 |
| ≥1 ICD diagnosis code and ≥1 prescription | ≥1 ICD-9 555.x in electronic health record AND ≥1 mention of 5-aminosalicylate, antibiotic, corticosteroid, immunomodulator, anti-TNF or natalizumab Excluded if had code for rheumatoid arthritis (714.x) or multiple sclerosis (340, 341.9, 323.9). Determined CD vs UC based on proportion. PPV 100% | United States Restrepo 2016 Validation years: Not reported Electronic health record (presumably inpatient or outpatient) No minimum follow-up No age restriction | 6 |
| ≥1 ICD diagnosis code and ≥1 prescription | ≥1 code and recorded in the SWIBREG Quality Register and received a biologic No mention of exclusions Sensitivity: 90% Specificity: 96% PPV: 97% | Sweden Shrestha 2020 Validation years: 1999-2017 Included in Register No minimum follow-up No age restriction | 3 |
| ≥1 ICD diagnosis code and ≥1 prescription | ≥1 ICD-10 K50.x code and ≥1 prescription for 5-aminosalicylate, immunomodulator, anti-TNF No mention of exclusions Sensitivity: 98% Specificity: 98% PPV: 98% NPV: 98% | South Korea Lee 2019 Validation year: 2011 Inpatient or outpatient No minimum follow-up No age restriction | 6 |
| ≥1 ICD diagnosis code and ≥1 prescription and met criteria for diagnosis based on NLP algorithm | ≥1 ICD-9 555.x in inpatient or outpatient setting AND ≥1 electronic prescription for 5-aminosalicylate, corticosteroids, immunomodulator or anti-TNF AND NLP definition met No mention of exclusions Sensitivity 69%-72% Specificity 97% PPV 98% AUC 0.95 | United States Ananthakrishnan 2013 Liao 2015 Validation years: Not reported Inpatient or outpatient No minimum follow-up No age restriction | 75 & 98 |
| ≥1 ICD diagnosis code and included in registry | ≥1 ICD-10 K50.x in inpatient or outpatient setting AND registered in rare disease database as Crohn’s disease (RID V130) No mention of exclusions Sensitivity 94.5%-98.3% Specificity 93.5% | South Korea Soh 2019 validated 2010-2013 Park 2018 validated 2010-2013 Kim 2015 validated 2006-2012 Inpatient or outpatient No minimum follow-up No age restriction | 10 & 19 & 58 |
| ≥1 ICD diagnosis code and included in registry | ≥1 ICD-7 572.00, 572.09; ICD-8 563.00; ICD-9 555.x; or ICD-10 K50.x code in inpatient or outpatient specialty visit AND registered at least once in a national IBD registry Mixed CD and UC codes considered IBD-U PPV 90% | Sweden Jakobsson 2017 Validation years: 1987-2015 Inpatient or outpatient specialty visit No minimum follow-up No age restriction | 28 |
| ≥2 diagnosis codes | ≥2 ICD-9 555.x codes with ≥1 outpatient If 556.x then exclude PPV 84% | United States Hou 2014 Validation years: 1999-2009 Inpatient or outpatient No minimum follow-up Adults (military veterans) | 35 |
| ≥2 diagnosis codes | ≥2 ICD-9-CM 555.x codes with ≥1 colonoscopy on same date as a 555.x code If 556.x then exclude Sensitivity: 49% Specificity: 88% PPV: 81% | United States Singla 2020 Validation years: 1996-2012 Inpatient or outpatient 3-y minimum follow-up Adults (active duty military) | 1 |
| ≥3 diagnosis codes | ≥3 ICD-9-CM 555.x codes from a gastroenterologist or surgeon If 556.x or 558.x then exclude Sensitivity: 71% Specificity: 86% PPV: 84% | United States Limketkai 2019 Validation years: 1998-2011 Inpatient or outpatient 3-y minimum follow-up Adults (active duty military) | 2 |
| ≥2 ICD diagnosis codes | ≥2 ICD-9 555.x in inpatient or outpatient setting No mention of exclusions Sensitivity 82% PPV 88% | United States Liu 2009 Validation years: 1996-2002 Inpatient or outpatient ≥12 mo of enrollment No age restriction | 21 |
| ≥3 diagnosis codes | ≥3 ICD-8 563.x or ICD-10 K50.x in inpatient or outpatient setting No mention of exclusions PPV: 75% | Denmark Rye 2021 Validation years: 1998-2015 Inpatient or outpatient No minimum follow-up Age ≥50 y | 0 |
| Number of ICD encounters within a time period | ≥2 hospitalizations or ≥4 physician claims or ≥2 ambulatory surgery visits for ICD-9 555.x or ICD-10 K50.x within 2 y Used number of CD visits among IBD visits to distinguish CD from UC Sensitivity: 94% Specificity: 99% | Canada Rezaie 2012 Validation years: 1997-2007 Inpatient or outpatient No minimum follow-up No age restriction | 24 |
| Number of ICD encounters within a time period | ≥9 ICD-9 555.x or 556.x or ICD-10 K50.x or K51.x. 5/9 of the most recent visits must be for CD (ICD-9 555.x or ICD-10 K50.x). All 9 codes must occur within a 4-y period. Accuracy 95.6% | Canada Benchimol 2014 Validation years: 2001-2006 Inpatient or outpatient No minimum follow-up Adults (≥18 y) | 58 |
| Number of ICD encounters within a time period | ≥7 IBD physician visits: ≥5 of last 7 coded for CD (555.x, K50.x) <7 IBD physician visits: All visits for ICD-9 555.x or ICD-10 K50.x All visits within a 3-y period. Sensitivity: 95% Specificity: 86% PPV: 92% NPV: 91% | Canada Benchimol 2009 Validation years: 2001-2005 Outpatient No minimum follow-up Pediatric (<18 y) | 109 |
| Number of ICD encounters within a time period | For residents of the province for ≥2 years: ≥5 outpatient encounters or hospitalizations for ICD-9 555.x or 556.x For residents of the province for <2 years: ≥3 outpatient encounters or hospitalizations for ICD-9 555.x or 556.x If a combination of CD and UC codes observed, required at least 9 codes. If majority of 9 most recent codes are 555.x then CD. Sensitivity 89% Specificity 90% | Canada Bernstein 1999 Validation years: 1984-1995 Inpatient or outpatient No minimum follow-up No age restriction | 147 |
Abbreviations: AUC, area under the curve; CD, Crohn’s disease; IBD, inflammatory bowel disease; IBD-U, inflammatory bowel disease unclassified; ICD-9, International Classification of Diseases–Ninth Revision; ICD-9-CM, International Classification of Diseases–Ninth Revision–Clinical Modification; ICD-10, International Classification of Diseases–Tenth Revision; NLP, natural language processing; NPV, negative predictive value; PPV, positive predictive value; TNF, tumor necrosis factor alpha; UC, ulcerative colitis.
Crohn’s Disease Algorithm Case Definitions, Characteristics of Validation Studies for Each Definition, and Studies Citing the Definition.
| Definition . | Specific Definition and Diagnostic Accuracy . | Characteristics of Validation Study . | Reference . |
|---|---|---|---|
| ≥1 ICD diagnosis code | ≥1 ICD-8 563.0 or ICD-9 555.x code during hospitalization No mention of exclusions PPV 87% | United Kingdom Barton 1989 Validation years: 1968-1983 Inpatient only No minimum follow-up Pediatric (≤20 y) | 37 |
| ≥1 ICD diagnosis code | ≥1 ICD-8 563.01 during hospitalization If 563.19 or 569.04 then exclude Sensitivity 94% | Denmark Fonager 1996 Validation years: 1988-1992 Inpatient only No minimum follow-up No age restriction | 58 |
| ≥1 ICD diagnosis code | ≥1 ICD-9 555.x during hospitalization If 556.x then exclude Sensitivity 82% | Italy Di Domenicantonio 2014 Validation years: 2000-2009 Inpatient only No minimum follow-up No age restriction | 18 |
| ≥1 ICD diagnosis code | ≥1 ICD-9 555.x in inpatient or outpatient setting No mention of exclusions PPV 18%-67% | United States Herrinton 2007 Validation years: 1999-2001 Inpatient or outpatient No minimum follow-up No age restriction | 45 |
| ≥1 ICD diagnosis code | ≥1 ICD-9 555.x in inpatient or outpatient setting No mention of exclusions Sensitivity 83% PPV 74%-82% | United States Herrinton 2008 Validation years: 1996-2002 Inpatient or outpatient ≥12 mo of enrollment No age restriction | 55 |
| ≥1 ICD diagnosis code | ≥1 ICD-9 555.0, 555.1, 555.2 or 555.9 in inpatient or outpatient setting No mention of exclusions for UC. Excluded unspecified intestinal obstruction (560.9). Sensitivity 92% Specificity 99% PPV 88% NPV 99% | United States Thirumurthi 2010 Validation years: 2000-2004 Inpatient or outpatient No minimum follow-up Adults (military veterans) | 34 |
| ≥1 ICD diagnosis code | ≥1 ICD-10 K50.x as primary diagnosis during hospitalization No mention of exclusions Sensitivity 98% NPV 99% | Canada Stepaniuk 2015 Validation years: 2007-2012 Inpatient only No minimum follow-up Adults (≥65 y) | 8 |
| ≥1 ICD diagnosis code | ≥1 ICD-10 K50.0, K50.1 or K50.8 during hospitalization If K51.x then exclude Sensitivity 30%-95% Specificity 89%-99% PPV 67%-97% NPV 66%-99% | Canada Ma 2017 Validation year: 2011 Inpatient only No minimum follow-up Adults (≥18 y) | 44 |
| ≥1 ICD diagnosis code | ≥1 ICD-10-CM code No mention of exclusions Sensitivity: 95% Specificity: 93% PPV: 91% NPV: 97% | Denmark Lo 2020 Validation years: 2003-2011 Inpatient and outpatient No minimum follow-up No age restriction | 1 |
| ≥1 ICD diagnosis code and prescription | ≥1 ICD-10-CM K50.x code with 0 K51.x and 0 M35.x and ≥1 medication If K51.x or M35.x then exclude Sensitivity: 100% Specificity: 99% PPV: 97% NPV: 100% | Japan Morikubo 2021 Validation years: 2015-2019 Inpatient and Outpatient No minimum follow-up No age restriction | 0 |
| ≥1 ICD diagnosis code | ≥1 OXMIS/Read code 5630CR, 5630C, 5630ER, 0092LR in primary care records If 5631 then exclude Sensitivity 94% | United Kingdom Lewis 2002 Validation year: 1988-1997 Primary care only No minimum follow-up No age restrictions | 46 |
| ≥1 ICD diagnosis code and ≥1 prescription | ≥1 ICD-9 555.x in electronic health record AND ≥1 mention of 5-aminosalicylate, antibiotic, corticosteroid, immunomodulator, anti-TNF or natalizumab Excluded if had code for rheumatoid arthritis (714.x) or multiple sclerosis (340, 341.9, 323.9). Determined CD vs UC based on proportion. PPV 100% | United States Restrepo 2016 Validation years: Not reported Electronic health record (presumably inpatient or outpatient) No minimum follow-up No age restriction | 6 |
| ≥1 ICD diagnosis code and ≥1 prescription | ≥1 code and recorded in the SWIBREG Quality Register and received a biologic No mention of exclusions Sensitivity: 90% Specificity: 96% PPV: 97% | Sweden Shrestha 2020 Validation years: 1999-2017 Included in Register No minimum follow-up No age restriction | 3 |
| ≥1 ICD diagnosis code and ≥1 prescription | ≥1 ICD-10 K50.x code and ≥1 prescription for 5-aminosalicylate, immunomodulator, anti-TNF No mention of exclusions Sensitivity: 98% Specificity: 98% PPV: 98% NPV: 98% | South Korea Lee 2019 Validation year: 2011 Inpatient or outpatient No minimum follow-up No age restriction | 6 |
| ≥1 ICD diagnosis code and ≥1 prescription and met criteria for diagnosis based on NLP algorithm | ≥1 ICD-9 555.x in inpatient or outpatient setting AND ≥1 electronic prescription for 5-aminosalicylate, corticosteroids, immunomodulator or anti-TNF AND NLP definition met No mention of exclusions Sensitivity 69%-72% Specificity 97% PPV 98% AUC 0.95 | United States Ananthakrishnan 2013 Liao 2015 Validation years: Not reported Inpatient or outpatient No minimum follow-up No age restriction | 75 & 98 |
| ≥1 ICD diagnosis code and included in registry | ≥1 ICD-10 K50.x in inpatient or outpatient setting AND registered in rare disease database as Crohn’s disease (RID V130) No mention of exclusions Sensitivity 94.5%-98.3% Specificity 93.5% | South Korea Soh 2019 validated 2010-2013 Park 2018 validated 2010-2013 Kim 2015 validated 2006-2012 Inpatient or outpatient No minimum follow-up No age restriction | 10 & 19 & 58 |
| ≥1 ICD diagnosis code and included in registry | ≥1 ICD-7 572.00, 572.09; ICD-8 563.00; ICD-9 555.x; or ICD-10 K50.x code in inpatient or outpatient specialty visit AND registered at least once in a national IBD registry Mixed CD and UC codes considered IBD-U PPV 90% | Sweden Jakobsson 2017 Validation years: 1987-2015 Inpatient or outpatient specialty visit No minimum follow-up No age restriction | 28 |
| ≥2 diagnosis codes | ≥2 ICD-9 555.x codes with ≥1 outpatient If 556.x then exclude PPV 84% | United States Hou 2014 Validation years: 1999-2009 Inpatient or outpatient No minimum follow-up Adults (military veterans) | 35 |
| ≥2 diagnosis codes | ≥2 ICD-9-CM 555.x codes with ≥1 colonoscopy on same date as a 555.x code If 556.x then exclude Sensitivity: 49% Specificity: 88% PPV: 81% | United States Singla 2020 Validation years: 1996-2012 Inpatient or outpatient 3-y minimum follow-up Adults (active duty military) | 1 |
| ≥3 diagnosis codes | ≥3 ICD-9-CM 555.x codes from a gastroenterologist or surgeon If 556.x or 558.x then exclude Sensitivity: 71% Specificity: 86% PPV: 84% | United States Limketkai 2019 Validation years: 1998-2011 Inpatient or outpatient 3-y minimum follow-up Adults (active duty military) | 2 |
| ≥2 ICD diagnosis codes | ≥2 ICD-9 555.x in inpatient or outpatient setting No mention of exclusions Sensitivity 82% PPV 88% | United States Liu 2009 Validation years: 1996-2002 Inpatient or outpatient ≥12 mo of enrollment No age restriction | 21 |
| ≥3 diagnosis codes | ≥3 ICD-8 563.x or ICD-10 K50.x in inpatient or outpatient setting No mention of exclusions PPV: 75% | Denmark Rye 2021 Validation years: 1998-2015 Inpatient or outpatient No minimum follow-up Age ≥50 y | 0 |
| Number of ICD encounters within a time period | ≥2 hospitalizations or ≥4 physician claims or ≥2 ambulatory surgery visits for ICD-9 555.x or ICD-10 K50.x within 2 y Used number of CD visits among IBD visits to distinguish CD from UC Sensitivity: 94% Specificity: 99% | Canada Rezaie 2012 Validation years: 1997-2007 Inpatient or outpatient No minimum follow-up No age restriction | 24 |
| Number of ICD encounters within a time period | ≥9 ICD-9 555.x or 556.x or ICD-10 K50.x or K51.x. 5/9 of the most recent visits must be for CD (ICD-9 555.x or ICD-10 K50.x). All 9 codes must occur within a 4-y period. Accuracy 95.6% | Canada Benchimol 2014 Validation years: 2001-2006 Inpatient or outpatient No minimum follow-up Adults (≥18 y) | 58 |
| Number of ICD encounters within a time period | ≥7 IBD physician visits: ≥5 of last 7 coded for CD (555.x, K50.x) <7 IBD physician visits: All visits for ICD-9 555.x or ICD-10 K50.x All visits within a 3-y period. Sensitivity: 95% Specificity: 86% PPV: 92% NPV: 91% | Canada Benchimol 2009 Validation years: 2001-2005 Outpatient No minimum follow-up Pediatric (<18 y) | 109 |
| Number of ICD encounters within a time period | For residents of the province for ≥2 years: ≥5 outpatient encounters or hospitalizations for ICD-9 555.x or 556.x For residents of the province for <2 years: ≥3 outpatient encounters or hospitalizations for ICD-9 555.x or 556.x If a combination of CD and UC codes observed, required at least 9 codes. If majority of 9 most recent codes are 555.x then CD. Sensitivity 89% Specificity 90% | Canada Bernstein 1999 Validation years: 1984-1995 Inpatient or outpatient No minimum follow-up No age restriction | 147 |
| Definition . | Specific Definition and Diagnostic Accuracy . | Characteristics of Validation Study . | Reference . |
|---|---|---|---|
| ≥1 ICD diagnosis code | ≥1 ICD-8 563.0 or ICD-9 555.x code during hospitalization No mention of exclusions PPV 87% | United Kingdom Barton 1989 Validation years: 1968-1983 Inpatient only No minimum follow-up Pediatric (≤20 y) | 37 |
| ≥1 ICD diagnosis code | ≥1 ICD-8 563.01 during hospitalization If 563.19 or 569.04 then exclude Sensitivity 94% | Denmark Fonager 1996 Validation years: 1988-1992 Inpatient only No minimum follow-up No age restriction | 58 |
| ≥1 ICD diagnosis code | ≥1 ICD-9 555.x during hospitalization If 556.x then exclude Sensitivity 82% | Italy Di Domenicantonio 2014 Validation years: 2000-2009 Inpatient only No minimum follow-up No age restriction | 18 |
| ≥1 ICD diagnosis code | ≥1 ICD-9 555.x in inpatient or outpatient setting No mention of exclusions PPV 18%-67% | United States Herrinton 2007 Validation years: 1999-2001 Inpatient or outpatient No minimum follow-up No age restriction | 45 |
| ≥1 ICD diagnosis code | ≥1 ICD-9 555.x in inpatient or outpatient setting No mention of exclusions Sensitivity 83% PPV 74%-82% | United States Herrinton 2008 Validation years: 1996-2002 Inpatient or outpatient ≥12 mo of enrollment No age restriction | 55 |
| ≥1 ICD diagnosis code | ≥1 ICD-9 555.0, 555.1, 555.2 or 555.9 in inpatient or outpatient setting No mention of exclusions for UC. Excluded unspecified intestinal obstruction (560.9). Sensitivity 92% Specificity 99% PPV 88% NPV 99% | United States Thirumurthi 2010 Validation years: 2000-2004 Inpatient or outpatient No minimum follow-up Adults (military veterans) | 34 |
| ≥1 ICD diagnosis code | ≥1 ICD-10 K50.x as primary diagnosis during hospitalization No mention of exclusions Sensitivity 98% NPV 99% | Canada Stepaniuk 2015 Validation years: 2007-2012 Inpatient only No minimum follow-up Adults (≥65 y) | 8 |
| ≥1 ICD diagnosis code | ≥1 ICD-10 K50.0, K50.1 or K50.8 during hospitalization If K51.x then exclude Sensitivity 30%-95% Specificity 89%-99% PPV 67%-97% NPV 66%-99% | Canada Ma 2017 Validation year: 2011 Inpatient only No minimum follow-up Adults (≥18 y) | 44 |
| ≥1 ICD diagnosis code | ≥1 ICD-10-CM code No mention of exclusions Sensitivity: 95% Specificity: 93% PPV: 91% NPV: 97% | Denmark Lo 2020 Validation years: 2003-2011 Inpatient and outpatient No minimum follow-up No age restriction | 1 |
| ≥1 ICD diagnosis code and prescription | ≥1 ICD-10-CM K50.x code with 0 K51.x and 0 M35.x and ≥1 medication If K51.x or M35.x then exclude Sensitivity: 100% Specificity: 99% PPV: 97% NPV: 100% | Japan Morikubo 2021 Validation years: 2015-2019 Inpatient and Outpatient No minimum follow-up No age restriction | 0 |
| ≥1 ICD diagnosis code | ≥1 OXMIS/Read code 5630CR, 5630C, 5630ER, 0092LR in primary care records If 5631 then exclude Sensitivity 94% | United Kingdom Lewis 2002 Validation year: 1988-1997 Primary care only No minimum follow-up No age restrictions | 46 |
| ≥1 ICD diagnosis code and ≥1 prescription | ≥1 ICD-9 555.x in electronic health record AND ≥1 mention of 5-aminosalicylate, antibiotic, corticosteroid, immunomodulator, anti-TNF or natalizumab Excluded if had code for rheumatoid arthritis (714.x) or multiple sclerosis (340, 341.9, 323.9). Determined CD vs UC based on proportion. PPV 100% | United States Restrepo 2016 Validation years: Not reported Electronic health record (presumably inpatient or outpatient) No minimum follow-up No age restriction | 6 |
| ≥1 ICD diagnosis code and ≥1 prescription | ≥1 code and recorded in the SWIBREG Quality Register and received a biologic No mention of exclusions Sensitivity: 90% Specificity: 96% PPV: 97% | Sweden Shrestha 2020 Validation years: 1999-2017 Included in Register No minimum follow-up No age restriction | 3 |
| ≥1 ICD diagnosis code and ≥1 prescription | ≥1 ICD-10 K50.x code and ≥1 prescription for 5-aminosalicylate, immunomodulator, anti-TNF No mention of exclusions Sensitivity: 98% Specificity: 98% PPV: 98% NPV: 98% | South Korea Lee 2019 Validation year: 2011 Inpatient or outpatient No minimum follow-up No age restriction | 6 |
| ≥1 ICD diagnosis code and ≥1 prescription and met criteria for diagnosis based on NLP algorithm | ≥1 ICD-9 555.x in inpatient or outpatient setting AND ≥1 electronic prescription for 5-aminosalicylate, corticosteroids, immunomodulator or anti-TNF AND NLP definition met No mention of exclusions Sensitivity 69%-72% Specificity 97% PPV 98% AUC 0.95 | United States Ananthakrishnan 2013 Liao 2015 Validation years: Not reported Inpatient or outpatient No minimum follow-up No age restriction | 75 & 98 |
| ≥1 ICD diagnosis code and included in registry | ≥1 ICD-10 K50.x in inpatient or outpatient setting AND registered in rare disease database as Crohn’s disease (RID V130) No mention of exclusions Sensitivity 94.5%-98.3% Specificity 93.5% | South Korea Soh 2019 validated 2010-2013 Park 2018 validated 2010-2013 Kim 2015 validated 2006-2012 Inpatient or outpatient No minimum follow-up No age restriction | 10 & 19 & 58 |
| ≥1 ICD diagnosis code and included in registry | ≥1 ICD-7 572.00, 572.09; ICD-8 563.00; ICD-9 555.x; or ICD-10 K50.x code in inpatient or outpatient specialty visit AND registered at least once in a national IBD registry Mixed CD and UC codes considered IBD-U PPV 90% | Sweden Jakobsson 2017 Validation years: 1987-2015 Inpatient or outpatient specialty visit No minimum follow-up No age restriction | 28 |
| ≥2 diagnosis codes | ≥2 ICD-9 555.x codes with ≥1 outpatient If 556.x then exclude PPV 84% | United States Hou 2014 Validation years: 1999-2009 Inpatient or outpatient No minimum follow-up Adults (military veterans) | 35 |
| ≥2 diagnosis codes | ≥2 ICD-9-CM 555.x codes with ≥1 colonoscopy on same date as a 555.x code If 556.x then exclude Sensitivity: 49% Specificity: 88% PPV: 81% | United States Singla 2020 Validation years: 1996-2012 Inpatient or outpatient 3-y minimum follow-up Adults (active duty military) | 1 |
| ≥3 diagnosis codes | ≥3 ICD-9-CM 555.x codes from a gastroenterologist or surgeon If 556.x or 558.x then exclude Sensitivity: 71% Specificity: 86% PPV: 84% | United States Limketkai 2019 Validation years: 1998-2011 Inpatient or outpatient 3-y minimum follow-up Adults (active duty military) | 2 |
| ≥2 ICD diagnosis codes | ≥2 ICD-9 555.x in inpatient or outpatient setting No mention of exclusions Sensitivity 82% PPV 88% | United States Liu 2009 Validation years: 1996-2002 Inpatient or outpatient ≥12 mo of enrollment No age restriction | 21 |
| ≥3 diagnosis codes | ≥3 ICD-8 563.x or ICD-10 K50.x in inpatient or outpatient setting No mention of exclusions PPV: 75% | Denmark Rye 2021 Validation years: 1998-2015 Inpatient or outpatient No minimum follow-up Age ≥50 y | 0 |
| Number of ICD encounters within a time period | ≥2 hospitalizations or ≥4 physician claims or ≥2 ambulatory surgery visits for ICD-9 555.x or ICD-10 K50.x within 2 y Used number of CD visits among IBD visits to distinguish CD from UC Sensitivity: 94% Specificity: 99% | Canada Rezaie 2012 Validation years: 1997-2007 Inpatient or outpatient No minimum follow-up No age restriction | 24 |
| Number of ICD encounters within a time period | ≥9 ICD-9 555.x or 556.x or ICD-10 K50.x or K51.x. 5/9 of the most recent visits must be for CD (ICD-9 555.x or ICD-10 K50.x). All 9 codes must occur within a 4-y period. Accuracy 95.6% | Canada Benchimol 2014 Validation years: 2001-2006 Inpatient or outpatient No minimum follow-up Adults (≥18 y) | 58 |
| Number of ICD encounters within a time period | ≥7 IBD physician visits: ≥5 of last 7 coded for CD (555.x, K50.x) <7 IBD physician visits: All visits for ICD-9 555.x or ICD-10 K50.x All visits within a 3-y period. Sensitivity: 95% Specificity: 86% PPV: 92% NPV: 91% | Canada Benchimol 2009 Validation years: 2001-2005 Outpatient No minimum follow-up Pediatric (<18 y) | 109 |
| Number of ICD encounters within a time period | For residents of the province for ≥2 years: ≥5 outpatient encounters or hospitalizations for ICD-9 555.x or 556.x For residents of the province for <2 years: ≥3 outpatient encounters or hospitalizations for ICD-9 555.x or 556.x If a combination of CD and UC codes observed, required at least 9 codes. If majority of 9 most recent codes are 555.x then CD. Sensitivity 89% Specificity 90% | Canada Bernstein 1999 Validation years: 1984-1995 Inpatient or outpatient No minimum follow-up No age restriction | 147 |
Abbreviations: AUC, area under the curve; CD, Crohn’s disease; IBD, inflammatory bowel disease; IBD-U, inflammatory bowel disease unclassified; ICD-9, International Classification of Diseases–Ninth Revision; ICD-9-CM, International Classification of Diseases–Ninth Revision–Clinical Modification; ICD-10, International Classification of Diseases–Tenth Revision; NLP, natural language processing; NPV, negative predictive value; PPV, positive predictive value; TNF, tumor necrosis factor alpha; UC, ulcerative colitis.
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