Patch test results to the Spanish baseline patch test series according to age groups: A multicentric prospective study from 2019 to 2023.

Introduction: Patch test results may be influenced by age-related factors. However, there is still discordant evidence between age and patch test results.

Objectives: We aim to evaluate the patch test results reflecting skin sensitisation, their relevance and association with clinical features by age group.

Methods: Prospective multicentric study of all patients patch tested with the Spanish baseline series in participating centres. Age groups were pre-defined as children (0- to 11-years), adolescents (12- to 18-years), young adults (19- to 30-years), middle-aged adults (31- to 65-years) and older adults (≥66-years). Occurrence of sensitisation, relevance and clinical features were compared by age group. Factors associated with skin sensitisation were investigated with multivariate logistic regression.

Results: A total of 13 368 patients were patch-tested. Differences in positive patch test results and relevance by age were detected with the highest proportion in middle-aged adults. Age-related trend differences were found for nickel, potassium dichromate, caines, colophony, Myroxylon pereirae resin, 2-hydroxyethyl methacrylate and limonene hydroperoxide. The multivariate logistic analysis (adjusted for sex, atopic dermatitis, body location and occupational dermatitis) showed an association between the age group of 31-65 (OR: 1.41, 95% CI: 1.26-1.58) and above 66-years (OR: 1.15, 95% CI: 1.01-1.32) with a higher proportion of positive results, compared with young adults.

Conclusions: Positive patch test results vary according to age, with the highest occurrence in middle-aged adults. Most haptens did not present age-related differences, reinforcing the use of baseline series regardless of age.