Seasonal variation of dermatologic disease in the USA: a study of office visits from 1990 to 1998.

BACKGROUND Seasonal variation has been demonstrated in many diseases, including certain skin diseases. OBJECTIVE To determine whether there is seasonal variation in dermatologic office visits in the USA. METHODS Data on dermatologic office visits were obtained from representative visits to outpatient physicians in the USA from the National Ambulatory Medical Care Survey from 1990 to 1998. Office visit seasonality was examined for all skin conditions, and individually for the 15 most commonly diagnosed conditions. RESULTS Office visits for skin conditions were seasonal (P = 0.002). The magnitude of variation can be roughly expressed by the following scheme: actinic keratosis (P = 0.0001) > acne (P = 0.0001) > folliculitis (P = 0.002) > dyschromia (P = 0.01) > seborrheic keratosis (P = 0.04) > psoriasis (P = 0.07) > seborrheic dermatitis (P = 0.09). Visits for skin cancer, not otherwise specified (skin cancer NOS), atopic dermatitis, cysts, common wart, wart, not otherwise specified (wart NOS), rosacea, contact dermatitis, and benign tumors showed no significant seasonal variations or trends. CONCLUSIONS Dermatologic office visits are seasonal, with visits for individual diseases varying in their magnitude of seasonality. This seasonal variation may be a result of biological and nonbiological variables.