Background and aims Previous examinations of International Classification of Disease, Ninth Revision, Clinical Modification (ICD-9-CM) codes to predict accuracy of diagnosis in inflammatory bowel disease have had limited chart review to confirm diagnosis. We aimed to evaluate using the ICD-9-CM for identifying Crohn’s disease (CD) in a large electronic health record (EHR) database.
Methods This is a retrospective case-control study with a 3:1 allocation of EHRs of active duty service members diagnosed with CD from 1996 to 2012. Subjects were selected by having two ICD-9-CM codes for CD and none for ulcerative colitis during the study period. Gastroenterologists reviewed each chart and confirmed the diagnosis of CD by analysing medication history and clinical, endoscopic, histological, and radiographic exams.
Results 300 cases of CD were selected; 14 cases were discarded due to lack of data, limiting analysis to 284 subjects. Two diagnostic codes for CD had sensitivity and specificity of 1.0 and 0.53 respectively, for confirmed CD. If two or more encounters listing CD were with a gastroenterologist, the sensitivity and specificity was 0.71 and 0.87 respectively. If two encounters included a colonoscopy was performed at the same time as a CD code, sensitivity and specificity was 0.49 and 0.88 respectively.
Conclusions The relatively poor specificity of ICD-9-CM codes in making the diagnosis of CD should be taken into consideration when interpreting results and when conducting research using such codes. Limiting these codes to patients given this diagnosis by a gastroenterologist, or to those who had a colonoscopy at the time of a diagnosis, increases the specificity, although at cost of sensitivity, especially for colonoscopy.
- Crohn's disease
- ulcerative colitis
- irritable bowel syndrome
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Contributors MS: chart review, analysis, drafting of the manuscript, and guarantor of the article. SH: study design, analysis, manuscript revision, critical review of the manuscript. EAK: analysis, critical review of the manuscript. BR: chart review, critical review of the manuscript. JB: study design, manuscript revision. SRB: study design, interpretation of results and analysis, manuscript revision, critical review of the manuscript.
Funding SH and SRB were supported in part by Congressionally Directed Medical Research Program Grant PR110833.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval This study was approved by the Institutional Review Boards of all involved institutions and complied with the highest standards of ethical research.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information. The data are collated from the military’s Electronic Health Record.
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