ICD-9-CM coding of emergency department visits for food and insect sting allergy.
OBJECTIVE
Little is known about the role of International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes for identification of specific allergic reactions in the emergency department (ED).


METHODS
Investigators in 10 EDs reviewed 1395 charts of consecutive patients presenting with food allergy (ICD-9-CM codes 693.1 and 995.60 to 995.69) and insect sting allergy (code 989.5). They also reviewed charts of patients with "unspecified" allergic reactions (codes 995.0 [other anaphylactic shock] and 995.3 [allergy, unspecified]) to identify additional patients with food or insect sting allergy.


RESULTS
Of 406 patients with food allergy, 216 patients (53%) were coded as food allergy, whereas the remaining 190 patients (47%) were not. Of 394 patients with insect sting allergy, 341 (87%) were coded as insect sting allergy, whereas 53 patients (13%) were not. Characteristics of ICD-9-CM-identified compared with chart-review-identified patients differed for both food and insect sting allergy. ICD-9-CM-identified patients with food allergy were less likely to experience anaphylaxis.


CONCLUSIONS
Almost half the patients with food allergy would have been missed by using food-specific ICD-9-CM codes alone, whereas only 13% of patients with insect sting allergy would have been missed. Furthermore, characteristics of these allergy patients would have been biased by studying only patients identified by using the allergen-specific ICD-9-CM codes.
Clark
Sunday
S
EMNet Coordinating Center, Department of Emergency Medicine, Massachusetts General Hospital, Boston, MA 02114, USA. sclark3@partners.org
Gaeta
Theodore J
TJ
Kamarthi
Geeta S
GS
Camargo
Carlos A
CA
D000328:Adult; D000818:Animals; D015331:Cohort Studies; D004636:Emergency Service, Hospital / Q000592:standards*; D005260:Female; D005512:Food Hypersensitivity / Q000175:diagnosis* / Q000503:physiopathology / Q000628:therapy; D005568:Forms and Records Control / Q000379:methods; D019983:Guideline Adherence / Q000706:statistics & numerical data*; D006801:Humans; D007299:Insect Bites and Stings / Q000150:complications* / Q000188:drug therapy; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies