Limits of ICD-9-CM code usefulness in epidemiological studies of contact and other types of dermatitis.
BACKGROUND
International Classification of Diseases, Version 9, Clinical Modification (ICD-9-CM) coding information used for billing is readily available in computerized form.


OBJECTIVE
The purpose of this article is to determine the usefulness of ICD-9-CM codes in a descriptive dermatoepidemiological study of contact and other dermatitis.


METHODS
Prospective recording of specific dermatologic diagnoses and the ICD-9-CM code assigned for each diagnosis was performed for all patient visits to the author's dermatology clinics for 6 months.


RESULTS
There were 2,524 patient visits with 4,451 diagnoses, of which 789 diagnoses were dermatitis. The 10 different diagnostic categories of dermatitis had eight associated ICD-9-CM codes. Allergic contact dermatitis with 247 visits, irritant contact dermatitis with 30 visits, and nummular dermatitis with 61 visits shared one diagnostic code. Thus, 43% of visits for dermatitis were intermixed by having the same ICD-9-CM code.


CONCLUSIONS
Lack of one-to-one correspondence of ICD-9-CM codes with dermatitis diagnostic categories creates a situation in which ICD-9-CM codes are not useful for dermatoepidemiological studies of contact and other types of dermatitis. This could be corrected by assigning additional five-digit ICD-9-CM codes to cover each type of dermatitis. Coding for specific allergens or irritants is not feasible with the current five-digit ICD-9-CM codes.
Shenefelt
P D
PD
Division of Dermatology and Cutaneous Surgery, Department of Internal Medicine, College of Medicine, University of South Florida, Tampa, FL 33612, USA.
D000328:Adult; D000368:Aged; D000485:Allergens / Q000145:classification; D003872:Dermatitis / Q000145:classification / Q000453:epidemiology*; D017449:Dermatitis, Allergic Contact / Q000453:epidemiology; D003877:Dermatitis, Contact / Q000145:classification / Q000453:epidemiology*; D017453:Dermatitis, Irritant / Q000453:epidemiology; D005260:Female; D005431:Florida / Q000453:epidemiology; D005568:Forms and Records Control / Q000379:methods; D006801:Humans; D007509:Irritants / Q000145:classification; D008297:Male; D008499:Medical Records; D008875:Middle Aged; D009819:Office Visits / Q000706:statistics & numerical data; D011446:Prospective Studies
D000485:Allergens; D007509:Irritants