Israel Medical Association Journal

Background: Allergic contact dermatitis (ACD), a prevalent skin disorder marked by delayed hypersensitivity reactions to specific allergens, is commonly diagnosed through patch testing. Previous studies have indicated lower rates of positive patch tests in summer months compared to winter months.

Objectives: To investigate whether there is a difference in the proportion of positive patch test results between summer and winter months.

Methods: A retrospective study was performed on 1128 patients, with 14 individuals undergoing two tests each, resulting in a total of 1142 patch tests. The tests were conducted at a major tertiary referral center between 2016 and 2020. The data set encompassed patient demographics and comprehensive patch test results.

Results: Of the 1142 tests conducted, 808 (70.8%) yielded a positive response. The most frequently administered test series was the European standard series, conducted for 1135 (99.3%) of the tests, with 559/1135 (49.2%) showing positive results, followed by the cosmetics series (394/1120, 35.1%) and fragrances series (61/118, 51.7%). No statistically significant difference was observed in the proportion of positive patch tests between summer and winter months (313/419, 74.7% vs. 175/245, 71.4%, respectively; P-value = 0.35). There was no statistically significant difference in the rate of testing each specific series between the summer and winter months, except for the fragrances series.

Conclusions: We found no significant difference in the positive patch test rates between the summer and winter months. Therefore, patch testing can be reliably conducted during the summer without an increased risk of false-negative results.

Background: Contact dermatitis is an inflammatory skin disorder characterized by an erythematous pruritic rash. The disorder can be either irritant or allergic. Allergic contact dermatitis is diagnosed by patch testing along with patient history.

Objectives: To review the results of patch tests conducted thought 2 years and to present real-life data characterizing clinical features and comparing prevalent local allergens to the ones common worldwide.

Methods: The retrospective cohort included 517 participants (384 females and 133 males) who underwent patch testing during a 2-year period. For each patient, clinical and demographic data were collected, and statistical analysis was conducted.

Results: We found that 261 patients had a positive test for at least one allergen. More females tested positive than males (52.9% vs. 43.6%). Test indications other than dermatitis were associated with a negative result. Hands, head, and neck were the most prevalent body parts affected. Patients with a background of atopic dermatitis had a higher rate of contact sensitization (69 vs. 43). Patients with a specific suspected offending allergen had significantly higher contact sensitizations. The most common allergen was nickel.

Conclusions: Patch testing should be conducted in patients with relevant dermatological findings accompanied by taking a thorough medical history. Clinicians should be updated on emerging allergens and exposure trends.