Identification of Inpatient Allergic Drug Reactions Using ICD-9-CM Codes

Publication date: Available online 31 July 2018

Source: The Journal of Allergy and Clinical Immunology: In Practice

Author(s): Rebecca R. Saff, Yu Li, Nikita Santhanakrishnan, Carlos A. Camargo, Kimberly G. Blumenthal, Li Zhou, Aleena Banerji

Abstract

Background

The study of allergic drug reactions has been limited due to challenges in identifying and confirming cases.

Objective

To determine the utility of ICD-9-CM codes for identifying inpatient allergic drug reactions and compare findings to prior data in the emergency department.

Methods

By reviewing medical records of inpatients with ICD-9-CM codes and E codes suggestive of allergic drug reactions at a large urban academic medical center, we determined codes that yielded the most drug allergy cases and identified culprit drugs.

Results

In 2005 and 2010, 3,337 and 5,282 possible allergic drug reactions during hospitalization were identified and 1,367 were reviewed. Allergic drug reactions were found in 409 (30.1%) of the reviewed charts with 172 (29.7%) in 2005 and 237 (30.5%) in 2010. The codes that identified the highest percentage of true allergic drug reactions were: Dermatitis due to drug (693.0), allergic urticaria (708), angioneurotic edema (995.1) and anaphylaxis (995.0). Antibiotics were the most common cause (44.4%); however, multiple drugs classes were often identified as likely culprits.

Conclusion

Specific ICD-9-CM codes can identify patients with allergic drug reactions, with antibiotics accounting for almost half of true reactions. The majority of patients with codes 693.0, 995.1, 708, and 995.0 had allergic drug reactions, with 693.0 as the highest yield code. An aggregate of multiple specific codes consistently identifies a cohort of patients with confirmed allergic drug reactions.