A population-based survey of eczema prevalence in the United States.
BACKGROUND
Eczema and atopic dermatitis (AD) are recognized as major health problems worldwide. Prevalence estimates are as high as one-third of the population, depending on the country studied, the age range of the subjects, and the diagnostic criteria used. National estimates of prevalence for the US population are lacking.


OBJECTIVE
To examine the public health problem posed by eczema, AD, and eczematous conditions in the United States by analyzing disease and symptom prevalence, estimating the number of undiagnosed cases, and assessing comorbidities.


METHODS
A self-administered questionnaire was sent to a sample of households (N = 60,000) representative of the US population. A designated member responded with information on symptoms, diagnoses, and impact for affected household members; 42,249 households (70%) responded, representing 116,202 individuals. Empirical eczema was defined by itching/scratching and red/inflamed rash or excessive dryness/scaling. Empirical AD was defined by itching/scratching and red/inflamed rash, excessive dryness/scaling, skinfold location, early onset, symptoms lasting or 14 days, or a physician diagnosis of asthma or of allergic rhinitis or hay fever.


RESULTS
Of the population studied, 17.1% reported at least one of four eczematous symptoms; empirically defined eczema was found in 10.7%, and empirically defined AD was found in 6%. Prevalence decreased with increasing income. Approximately two-thirds of individuals with an empirical diagnosis of eczema or AD had moderate to severe symptoms, one-third had sleep disturbances, and one-quarter had chronic unremitting symptoms. Just over one-third (37.1%) of those with symptoms reported a physician diagnosis. Peak onset for empirical AD occurred in the group of subjects aged <or= 5 years. For empirical eczema, peak onset occurred in the group aged 18 to 29 years, and comorbid asthma and hay fever/allergic rhinitis were more prevalent.


CONCLUSIONS
A substantial proportion of the US population has symptoms of eczema or eczematous conditions; 31.6 million met the empirical symptom criteria for eczema, and 17.8 million met the empirical criteria for AD. Most cases are not diagnosed by a physician, which indicates that these conditions are undertreated and/or managed with nonprescription remedies.
Hanifin
Jon M
JM
Deparment of Dermatology, Oregon Health & Science University, 3303 SW Bond Ave, Portland, OR 97239-4501, USA. hanifinj@ohsu.edu
Reed
Michael L
ML
D000293:Adolescent; D000328:Adult; D000368:Aged; D001249:Asthma / Q000150:complications; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D003872:Dermatitis / Q000150:complications; D003876:Dermatitis, Atopic / Q000150:complications / Q000453:epidemiology* / Q000473:pathology; D004485:Eczema / Q000150:complications / Q000453:epidemiology* / Q000473:pathology; D005191:Family Characteristics; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D006255:Rhinitis, Allergic, Seasonal / Q000150:complications; D012893:Sleep Wake Disorders / Q000209:etiology; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires; D014481:United States / Q000453:epidemiology