Review: topical permethrin was more effective than topical crotamiton or lindane for scabies
Dr M Strong, University of Sheffield, Sheffield, UK;
Medline, EMBASE/Excerpta Medica, LILACS, INDMED, and Cochrane Infectious Diseases Group Specialised Register (all to February 2007); Cochrane Central Register of Controlled Trials (Cochrane Library, Issue 1, 2007); websites of registered clinical trials and grey literature sources (March 2007); and reference lists.
Study selection and assessment:
randomised controlled trials (RCTs) that compared systemic or local drug treatment with placebo, no intervention, or a different intervention or combination of interventions in children or adults with a clinical or parasitological diagnosis of scabies, or their contacts. 20 RCTs (n = 2392, follow-up range 1 wk to 1 mo) met the selection criteria; 17 were done in resource-poor countries. 6 trials described an adequate method of generating the random allocation sequence, 6 reported adequate allocation concealment, and 12 reported blinding. 3 trials had <80% follow-up.
treatment failure (persistence of original lesions, appearance of new lesions, or confirmation of a live mite). Secondary outcomes were patient-reported itch and adverse events.
Meta-analyses showed that permethrin resulted in fewer treatment failures than lindane or crotamiton, and ivermectin resulted in fewer failures than lindane (table). In individual trials, ivermectin had fewer treatment failures than placebo but more than permethrin (table). Of 7 trials reporting itch persistence, 2 reported a reduction with permethrin (v crotamiton, n = 94, relative risk reduction [RRR] 74%, 95% CI 35 to 89; v lindane, n = 391, RRR 44%, CI 14 to 63). No serious adverse events were reported in any trial.
In patients with scabies, topical permethrin had fewer treatment failures than topical crotamiton or lindane. Oral ivermectin had fewer treatment failures than lindane.
Strong M, Johnstone PW. Interventions for treating scabies. Cochrane Database Syst Rev 2007;(3):CD000320.
Clinical impact ratings: Dermatology 6/7; Developing countries 5/7; Family/General practice 6/7; Public/Community health 7/7
The systematic review by Strong and Johnstone assessed the effectiveness of scabicidal treatments. They conclude that topical permethrin is the most effective treatment overall, although ivermectin appears to be an effective oral agent. The review includes research primarily done in poorer countries, where poverty, crowding, and fewer resources mean scabies is more prevalent. Strong and Johnstone also note the lack of research for some treatments, variations in treatment protocols, and the need for recommendations on environmental cleaning or containment measures.
The findings are of particular interest to healthcare providers working in primary care, with marginalised populations, or in congregate settings such as long-term care. As a nurse practitioner working with people who are homeless, I am interested in accurate, evidence-based information to help me provide my clients with effective and safe anti-scabicidal treatment. The findings of Strong and Johnstone are consistent with my clinical experience and increase my confidence in the effectiveness of permethrin-based products for treating scabies. However, as the authors note, their meta-analysis does not fully address possible side effects.
It was interesting to note the limited number of anti-scabicidal products available. Many of the products assessed are potentially noxious agents, pesticides, or neurotoxins. Indeed, the authors state that while there are anecdotal reports of promising herbal remedies for scabies, such studies did not meet inclusion criteria for this review.