Administrative coding is specific, but not sensitive, for identifying eosinophilic esophagitis

Area of Science:

• Gastroenterology
• Health Informatics
• Epidemiology

Background:

• Administrative databases are crucial for population-based health studies.
• Accurate case identification is vital for reliable data.
• The validity of the ICD-9 code 530.13 for eosinophilic esophagitis (EoE) in administrative data was previously unconfirmed.

Purpose of the Study:

• To validate the accuracy of the ICD-9 code 530.13 for identifying eosinophilic esophagitis (EoE) cases in administrative health records.
• To assess the sensitivity and specificity of this code for EoE case definition.
• To explore methods for refining the case definition using procedural codes and insurance status.

Main Methods:

• Retrospective validation study using confirmed EoE cases from the UNC EoE Clinicopathologic Database (2008-2010).
• Utilized the Carolina Data Warehouse for administrative data, querying diagnostic and procedure codes.
• Calculated sensitivity and specificity of ICD-9 code 530.13, with iterative refinement and sensitivity analysis using 2011 data.

Main Results:

• The ICD-9 code 530.13 demonstrated high specificity (99%) but low initial sensitivity (37%) for EoE.
• Refining the definition with procedure codes or restricting to privately insured patients did not significantly alter these parameters.
• By 2011, sensitivity increased to 61% while specificity remained high at 99%.

Conclusions:

• The ICD-9 code 530.13 offers excellent specificity for identifying eosinophilic esophagitis (EoE) in administrative data, particularly from academic centers.
• The code's sensitivity is increasing, suggesting improved case capture over time.
• While the code identifies likely EoE cases, a significant number of actual cases may still be missed.