Teledermatology

What is telemedicine?

Telemedicine is the inevitable offshoot of rapid improvements in telecommunications and digital technologies. Dermatological conditions lend themselves to imaging. Consequently, the potential for teledermatology to improve the care of patients with skin disorders is considerable, especially given the overall shortage of dermatologists and the concomitant global burden of skin disease. But is teledermatology compatible with patch testing? Sometimes reading the results of a patch test in person in the office seems challenging enough. Is it a positive or an irritant reaction? Is it a mild 1+ reaction or doubtful? How detrimental to reading patch test results would the inability to palpate a reaction for induration be?

How reliable is teledermatology?

For the first time, the feasibility of using store-and-forward teledermatology to assess patch test results has been reported (Grey KR, Hagen SL, Hylwa SA, Warshaw EM. Utility of store and forward teledermatology for skin patch test readings. Dermatitis 2107: 28(2):152-161). In contrast to real-time interactive teledermatology, which requires clinicians and subjects to interact synchronously, store-and-forward systems transmit still images for assessment, which can be performed at a clinician’s convenience.

In the study 101 adults (70% female, mean age 50 years) were patch tested with the 70-allergen screening series of the North American Contact Dermatitis Group. One of two dermatologists experienced in patch testing read and scored the results in person at the time the patch test panels were removed (48 hours) and at the final reading (96-168 hours). One of two other investigators took photographs (in a carefully controlled and standardized fashion that eliminated all identifying information) of the patch test sites at both visits. The same dermatologists who performed the in-person readings performed the store-and-forward assessments of the images from the same patients. To eliminate recall bias, the photographs from the 48-hour visit were graded at least 4 weeks later and those from the final reading were graded at least 8 weeks later.

Agreement between the teledermatology and in-person gradings of the skin reactions was calculated and categorized as success, indeterminate, or failure. Of the 7070 possible pairs of comparisons (excluding negative/negative agreements, which included 6650 of the comparisons), 47% of the teledermatology readings at 48 hours and 54% of the final readings were successful. That is, patient counseling would have been conducted exactly the same based on either the in-person or teledermatology reading. The overall failure rate was 6%: of the 27 pairs, 7 were under-read and 20 were over-read. Most of the discordance involved mild (1+) and negative reactions although, surprisingly perhaps, there were also a few disagreements between strong positive (2+ or 3+) and negative reactions. Possible reasons underlying the failure to read the images correctly were misinterpretation of spread between two reactions, lighting, and lack of tactile feedback or patient-provided information such as the presence of itching.

The most problematic group reflected doubtful reactions, the interpretation of which may vary and be affected by a patient’s clinical history. Of the final readings, the clinical significance of 40% (167 pairs) was indeterminate. Compared to the in-person grade, 116 of these photographs were under-read and 51 were over-read. The authors suggested that the addition of a final determination of allergic or not allergic could help minimize indeterminate comparison points (e.g., a patient with a doubtful reaction to one formaldehyde-releasing allergen would likely be considered allergic if positive to multiple other formaldehyde releasers).

Overall, the results of this study were mixed. Although the majority of the comparisons were successful, the 54% rate is not overly robust. Whether the raters’ performance would improve with practice is unknown (albeit no significant differences between the two readers was found). Even with improvements in teledermatologic rating ability, limitations in patients’ ability to mark and remove patch test panels and to obtain high-quality photographs to send to their provider might negatively compensate for increased proficiency on the part of the teledermatology clinician. Given that the readers were experienced patch testers, clinicians with less expertise would likely fare less well.

Conclusions for teledermatology?

Although teledermatology for patch testing may not be ready for prime time, its potential should not be discounted. Continued technological improvements in visual clarity, perhaps combined with real-time interaction between patient and clinician, might overcome some of the limitations. Such scenarios become more feasible as mobile teledermatology (smartphones and tablets) expands. Despite a myriad of ethical, economic, legal, and clinical challenges to its implementation, teledermatology can help reach underserved populations and increase the efficiency of clinical practices. Furthermore, patients have reported satisfaction with teledermatology consultations and a willingness to pay for them. The volume of commercial telecommunication consultations in other aspects of dermatology continues to grow, and it would be surprising if this useful modality did not expand into the realm of patch testing as well.

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