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Nitpicking

With new school terms starting GPs are beginning to see the Autumn rush of children infected with head lice. It was timely that the BMJ published a systematic review of the clinical efficacy of topical treatments for head lice. Busy GPs have asked Bandolier for a short précis of the article.

Methods

The authors set some high standards for searching for studies and including them in their analysis. They even located eleven unpublished trials from Wellcome - comparing malathion and permethrin, though unfortunately the company demanded confidentiality, so they could not be used.

The criteria the authors used for inclusion and exclusion included important general issues like randomisation and blinding, and also a number of methodological issues particular to head lice studies. In the end they included in their analysis seven studies of 21 individual treatments, including placebo and eight compounds. The clinical end-point they chose was absence of viable lice or their eggs at 14 days after (usually) a single application.

Results

Cure rates with treatment with inactive vehicle were about 6%.
Treatment Cured/Total Percent cured NNT (95%CI)
Permethrin 1% 631/647 97 1.09 (1.00 - 1.20)
Lindane 1% 365/437 84 1.29 (1.16 - 1.45)
Pyrethrines 183/204 90 1.19 (1.08 - 1.34)
Carbaryl 0.5% 143/145 98 1.08 (1.00 - 1.18)
With active treatments they were higher, often above 80%. However, only permethrin 1% creme rinse showed efficacy in more than two studies with a lower 95% confidence interval of cure rate above 90%. In the table the data from the trials has been aggregated to show the number of patients treated and treated successfully to yield an average cure rate and NNTs. This supports the conclusion that the treatment of choice is permethrin at 1% strength with the lowest NNT (approaching 1) in the largest group of treated individuals.

Reference:

RH Vander Stichele, EM Dezeure, MG Bogaert. Systematic review of clinical efficacy of topical treatments for head lice. British Medical Journal 1995 311: 604-8.



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