Review - Reviewer's Assessment

1. Short summary / abstract
Objective To evaluate the efficacy and safety of 4% dimeticone lotion for treatment of head louse infestation.
Design Randomised controlled equivalence trial.
Setting Community, with home visits.
Participants 214 young people aged 4 to 18 years and 39 adults with active head louse infestation.
Interventions Two applications seven days apart of either 4.0% dimeticone lotion, applied for eight hours or overnight, or 0.5% phenothrin liquid, applied for 12 hours or overnight.
Outcome measures Cure of infestation (no evidence of head lice after second treatment) or reinfestation after cure.
Results Cure or reinfestation after cure occurred in 89 of 127 (70%) participants treated with dimeticone and 94 of 125 (75%) treated with phenothrin (difference -5%, 95% confidence interval -16% to 6%). Per protocol analysis showed that 84 of 121 (69%) participants were cured with dimeticone and 90 of 116 (78%) were cured with phenothrin. Irritant reactions occurred significantly less with dimeticone (3/127, 2%) than with phenothrin (11/125, 9%; difference -6%, -12% to -1%). Per protocol this was 3 of 121 (3%) participants treated with dimeticone and 10 of 116 (9%) treated with phenothrin (difference -6%, -12% to -0.3%).
Conclusion Dimeticone lotion cures head louse infestation. Dimeticone seems less irritant than existing treatments and has a physical action on lice that should not be affected by resistance to neurotoxic insecticides.

2. What question is the document addressing?
How does dimeticone lotion (a new and thus far unproven treatment for head lice) compare with phenothrin (a proven treatment, which despite evidence of its safety, many people are concerned about using - it’s potentially toxic, and can be absorbed transdermally).

3. Type of study
Randomised controlled, single-blinded equivalence trial.

4. Methods valid & appropriate?

Study appears to have been well planned and executed, using appropriate pharmaceutical and statistical methodologies. Dimeticone sounds like it is a pleasanter product than alternative treatments (malathion, phenothrin, permethrin, etc.), having less odour, being associated with fewer adverse events, and not being absorbed transdermally. It appears to work by a physical coating effect on the head lice, and so seems less likely to be toxic than preparations that work through their toxic effects.

5. Results / recommendations reliable?

6. Any major problems and biases?
The products differ sufficiently that subjects could not be blinded to which they were given; investigators assessing outcomes were blinded to the treatment. This was probably unavoidable and is unlikely to have significantly affected the outcome. Data included in the paper show very little difference between treatment groups, and very low dropout rates, which would tend to reduce the likelihood of bias.

7. Any other important / relevant studies which confirm or contradict?

8. Keywords
Head lice

Reviewer's Details:

Name:Peter English
(Society / Organisation / Advisory Committee):

*** Note: These are the views of a professional expert rather than an official statement from his or her society, organisation or advisory committee.

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