Challenges and Benefits to Patch Testing for Allergic Contact Dermatitis: A Canadian Patient Perspective

To the Editor:

Allergic contact dermatitis (ACD) is a type 4 hypersensitivity reaction to offending allergens. ¹ ACD is difficult to diagnose through history alone, so diagnosis and management of patients with ACD requires patch testing. ² Patch testing can be onerous for patients as they are required to avoid sweating, showering, or heavy lifting during the test. They must visit a dermatologist multiple times over a week for applications of allergens to their back and subsequent reading of results. ¹ Few dermatologists patch test in Canada, with all practicing in urban centres. ³ Consequently, general wait times are long, and patients may have to travel long distances to receive patch testing. Given the challenges with access to patch testing, and potentially burdensome process for patients, we sought to understand the patient experience of patch testing to help identify challenges and areas for quality improvement.

A total of 31 patients who underwent patch testing in Calgary or Regina completed an online survey from September 2022 to October 2023. Most respondents (90.32%) underwent patch testing in Calgary and visited the clinic 2 times over the patch testing period.

Most respondents (54.84%) were struggling with their skin rash for over 3 years before receiving patch testing. From referral, wait times for testing varied, but 32.26% of respondents reported that they waited 7 to 9 months, 22.58% waited 10 to 12 months, and 12.90% waited over a year. In fact, 74.19% of respondents endorsed “shorter wait times” as a suggested improvement for patch testing (Supplemental Table 1).

Overall, respondents endorsed inability to shower or exercise (70.97%), discomfort (58.06%), and long wait times (58.06%) as dislikes relating to during patch testing. Cost was not a major barrier for patients as patch testing is covered publicly in Canada (Supplemental Table 1); however, 41.94% of respondents had to take unpaid time off work. Receiving a diagnosis (77.42%), finding out which products were safe (61.29%), and seeing a specialist dermatologist (58.60%) were identified as major advantages to undergoing patch testing. Notably, 67.74% of respondents received a diagnosis of ACD through patch testing.

Despite limitations relating to small sample size and generalizability, these survey results demonstrate a distinct need and benefit to patch testing in Canada. A major area of concern for patients was the inability to shower, exercise, and discomfort associated with testing. These results highlight the importance of pre-test counselling, to ensure patients understanding of associated restrictions and discomforts. Respondents also identified wait times as a major dislike and suggested improvement to patch testing. Few dermatologists offer testing in Canada, ³ so it may be beneficial to explore methods to increase efficiency of testing, or to incentivise dermatologists to offer patch testing services. Overall, there is major utility in patch testing for ACD. However, it is integral to provide pre-test counselling for patients and to further explore strategies to improve access pertaining to wait times and availability of testing.