The inaccuracy of ICD-9-CM Code 530.2 for identifying patients with Barrett's esophagus

Barrett's esophagus (BE) is a chronic complication associated with gastroesophageal reflux disease. The ICD-9-CM code used for BE, 530.2, is also used for patients with 'ulcer of the esophagus.' We aimed to determine if the ICD-9-CM code of 530.2 is reliable for identifying cases of Barrett's esophagus within databases for research purposes. We reviewed the records of all patients assigned code 530.2 at two university medical center hospitals and a veterans' administration hospital over a cumulative 16-year period. Billing records provided information about where the code was assigned, whether it was a major or minor diagnosis, and if the code was assigned on multiple occasions for each patient. Histology and endoscopy records were reviewed to confirm the diagnosis of Barrett's esophagus. Among 435 patients with code 530.2 in their records, 354 (82%) had an esophageal biopsy reported and 393 (90%) had an endoscopy report available for review. Only 182 (42%) had specialized intestinal metaplasia documented in a biopsy from an area of salmon-colored mucosa arising above the esophagogastric junction (51% of those with histology available). There were 288 patients (66%) with an endoscopic diagnosis of Barrett's esophagus (73% of those with an endoscopy reported). Variables associated with documented specialized intestinal metaplasia were age >= 60 (OR 2.3; 95% CI 1.4-3.7), multiple assignments of 530.2 (OR 3.2; 95% CI 2.0-5.0), and assignment of 530.2 in a gastrointestinal (GI) clinic or an endoscopy unit (OR 3.5; 95% CI 2.0-6.3). The positive predictive value of the code being assigned in a GI location was 48% (95% CI 43-54%). Therefore, ICD-9-CM code of 530.2 is not specific for the diagnosis of Barrett's esophagus. The usage of code 530.2 in a GI setting was not sufficiently predictive of BE to be reliable for rigorous epidemiological studies.