Poison ivy: How effective are available treatments?
In this study, only one treatment approach significantly reduced pruritus. Three approaches were often associated with recurrences of rash or symptoms.
METHODS
We conducted this study between May 2010 and October 2014. The project was approved by the University of Oklahoma Health Sciences Center Institutional Review Board. Clinician members of OKPRN were invited to participate in the study via listserv, fax, or letter. We instructed clinicians and office staff to ask patients with Rhus dermatitis if they might be interested in participating in a study, which would require that they keep a symptom diary and would earn them a $20 gift card. Interested patients were given a packet of information, and a member of the research team later called the patients with additional information, including an explanation of informed consent and instructions on completing and returning the diary and written consent form.
Clinicians recorded information about the patient and the rash on a customized template, releasing it to the team after written consent was obtained from the patient. Categories for characterizing the rash were head/face, arms/hands, trunk, and legs/feet. A subset of 5 participating clinicians, selected to include a variety of practice types and patient populations, were also asked to produce, from their billing software, the number of patients and encounters in which poison ivy was addressed in each month of 2013.
On the diary, patients were instructed to record the presence or absence of pruritus, erythema, raised lesions, and vesicles/bullae at the end of each day until the rash resolved, or for 6 weeks following onset of the rash, whichever came first. Patients were asked to mail their diaries to the principal investigator once they were free of symptoms for one week or after 6 weeks from the onset of symptoms, whichever came first.
We asked both patients and clinicians to report medications used before and after the primary care encounter. A member of the research team assigned these medications to one of 12 categories: topical antihistamines, topical soaps (eg, Zanfel or Tecnu), topical astringents, other topical antipruritics, topical aloe vera, topical bleach, low-potency topical corticosteroids, moderate-potency topical corticosteroids, high-potency topical corticosteroids, oral antihistamines, oral corticosteroids, and parenteral corticosteroids.
We used independent T-tests to evaluate associations between baseline variables, patient-initiated treatments, and clinician-initiated treatments and the time to complete resolution of individual signs and symptoms and complete resolution of all signs and symptoms following the clinical encounter. We created additional outcome variables for initial resolution followed by recurrence of itching, erythema, papules, and vesicles. The purpose of these variables was to determine if some treatments were initially effective but without lasting effect.
We used the chi square test to assess associations between clinician-initiated treatments and recurrence of signs or symptoms following initial resolution. To account for chance associations resulting from multiple analyses, we chose to set the level of statistical significance at P=.01. However, because of the lower-than-projected sample size, we chose to also report variables with P<.05 so that the reader could judge the likelihood that a larger sample might have disclosed other important associations.
