Patch testing in an aged population without dermatitis: High prevalance of patch test positivity

image Epidermal immune function has been observed to decline in the aged. image The purpose of this study was to determine the prevalence and relevance of patch test reactivity in an aged population without dermatitis and compare this with patch test reactivity in healthy younger volunteers. image Patch testing with the North American Contact Dermatitis Group standard tray was performed on 82 healthy volunteers ranging in age from 68 to 87 years (mean age, 75 years), and the results were compared with those of 41 healthy younger volunteers (mean age, 24 years). A questionnaire regarding cutaneous symptoms was administered to both groups. image Thirty subjects in the older population (37%) had one or more positive patch test results compared with 6 members of the control group (15%) (P = .01). Common sensitizers in the older group included balsam of Peru (7 [9%]), fragrance (8 [10%]), neomycin (6 [7%]), nickel (5 [6%]), and methylchloroisothiazolinone/methylisothiazolinone (3 [4%]). A history of severe pruritus (without dermatitis) was associated with positive patch test results to balsam of Peru and nickel. image A high prevalence of positive patch test results in an aged population without dermatitis was observed. Factors contributing to the high prevalence of patch test reactivity in the aged population may include cumulative exposure to potential allergens over time, a preserved ability to develop contact allergy, and altered percutaneous absorption. Patch testing in the aged must be interpreted carefully because the results may relate to past rather than present relevance.