Title: A randomised, assessor blind, parallel group comparative efficacy trial of three head lice treatments in children

Transcription

1 Author's response to reviews Title: A randomised, assessor blind, parallel group comparative efficacy trial of three head lice treatments in children Authors: Stephen C Barker (s.barker@uq.edu.au) Phillip M Altman (pmaltman@bigpond.net.au) Version: 3 Date: 2 July 2010 Author's response to reviews: see over

2 Altman Biomedical Consulting Pty. Ltd. ABN Folly Point, Cammeray, NSW 2062 Australia Tel +61-(02) Fax mobile tel July 2010 Hayley Henderson Editorial Administrator BMC Series Journals BioMed CentralLiverpool Science Park131 Mount PleasantLiverpool L3 5TFUK hayley.henderson@biomedcentral.com Dear Hayley, Re: Manuscript Title: A randomised, assessor blind, parallel group comparative efficacy trial of three products for the treatment of head lice in children - melaleuca oil and lavender oil, pyrethrins and piperonyl butoxide, and a suffocation product I refer to our previous correspondence with BMC regarding the reformatting of our manuscript and the reviewers (3) comments on our manuscript. We have addressed all the reviewers concerns. We attach the reviewers comments (3) together with our responses to each comment. We would like to take the opportunity to thank each of the three reviewers for their constructive comments which have helped to assist in improving the manuscript. We look forward to your consideration and publication. Regards, Phillip Altman

3 Reviewer's report #1 All author s responses are in bold face type Title: A randomised, assessor blind, parallel group comparative efficacy trial of three head lice treatments in children Version: 1 Date: 15 April 2010 Reviewer: Ian Burgess Reviewer's report: This is an interesting and important paper but could do with some improvement to the presentation. Overall it is a useful contribution to the current debates about treatment methodology for head louse infestation and efficacy of active materials. Methods Objectives. In this section (which I think could be renamed Objectives and Interventions) you have given the components of one product but not of the others. Unless there is some compelling commercial reason not to, the components of all formulations should be described. Also the characteristics of the dosage form of each product, e.g. lotion, gel, pressurised mousse, etc., would be useful for those readers not familiar with the products. The heading Objectives was amended to Objectives and Interventions, see page 3 of the revised manuscript. The authors purposely did not name the active ingredient for NeutraLice Advance because there is no identifiable active ingredient. The product acts in the physical sense and this mode of action is not attributable to any one component. The Australian Therapeutic Goods Administration has approved the sale of this product as a medical device and the official inclusion on the Australian Register of Therapeutic Goods (ARTG) for this product does not include the identification of an active ingredient either in the approved literature, product information or packaging. Full disclosure of the formulation is given in the Objectives and Interventions section on page 3 of the manuscript. I note that the components of the NeutraLice Advance product appear identical to those of the Ulesfia product sold in the USA. I presume these two products are the same, but marketed under separate licences from the inventor. If this is the case I think you should find some way of stating the fact. NeutraLice Advance is not marketed under licence. The Sponsor has no way of confirming the proprietary formulation details of another product made by another company. The formulation is based on the Ulesfia patent (not registered in Australia) and is fully disclosed in the manuscript. Methodology Page 4, paragraph 2. The first sentence in this paragraph could be shortened by deletion of the final part after the words,...was determined by wet combing. Reviewer s recommendation was accepted see revised marked up manuscript. I hope it would be obvious that the measure would include both ITT and PP groups. Also, although an ITT analysis is a primary outcome analysis it is not

4 strictly an outcome measure and irrespective of that a PP analysis is not a secondary outcome measure but an extension and clarification of the analyses. Reviewer s recommendation was accepted see revised marked up manuscript (see last paragraph, page 4). Definitions Can I suggest that these are transferred to a Table or Text Box as at the moment they are inclined to break up the text flow. The Reviewer s recommendation was accepted see new Appendix 1 which contains all the definitions. Blinding Your description of the blinding measures is comprehensive. One thing is missing. Can you explain how did you avoid breaking the blind for assessors when some subjects were assessed in a school would have been followed up on day 8 and others on day 15, assuming the same team had already gone to the school on day 1 to check then? The blind was maintained. Subjects were entered on a staggered basis over a period of several weeks in the 3 schools, subjects did not all start or end at the same time. Evaluators were assessing subjects on a weekly basis over a 3 month period and the evaluators had no knowledge of the treatment. Treatment of siblings I think this paragraph could be much simplified and shortened. The first part If an enrolled subject had a primary-school aged sibling (aged 4 years to 12 years), the sibling was also examined for head lice, and if infested, either enrolled into the same treatment arm as the subject is fine. However, the next section is unnecessarily repetitive. Could you reword it along the lines of, Those siblings not enrolled (you can give reasons here), and those found to have eggs only (i.e. no live lice) were wet-combed-out at days 0 and 7 if the related subject received the Pyrethrins/piperonyl butoxide product, or wet-combed-out at days 0, 7 and 14 for siblings of subjects receiving Tea Tree/Lavender Oil and suffocation products. The Reviewer s recommendation was accepted see amendments to the text on page 5 of the manuscript. Treatment compliance I think the characteristics of subjects qualifying for PP status should be transferred to a Table or Text Box. The final bullet point of this list should be abbreviated and referred back to the description given in the Treatment of siblings section. The Reviewer s recommendation was accepted see new Appendix 2.

5 Dosage and dosage regimen I presume use of a shower cap for the Tea tree/lavender product was part of the instruction for the product. What was the shower cap made from? I think you should consider discussing the reason for using this cap in the Discussion section and also consider whether this was a contributory factor in the high incidence of adverse events in this group, perhaps by concentrating terpenoid vapours at scalp level. The shower cap was made of PVC. Words were added to the revision to indicate the shower cap was made of PVC. The Reviewer s recommendation was accepted and the reason for using the shower cap and the possible relationship to the adverse events was added to the Discussion section of the manuscript (see page 10). Criteria for evaluation of safety You interviewed the subjects, did anyone give a physical exam? I presume this was the case as the kids couldn t do it for themselves, or did you rely on parents to do it? A full medical examination by an MD was not done. But the scalp was examined for any sign of scalp disease this is described in the ms. All observations were conducted at the site of application within the school by skilled site staff. Statistical management Determination of sample size I am curious as to why you chose alpha at or less than but power at only 75%. It has been customary to aim for power of at least 80% in head louse studies and the trend is towards greater powering, i.e. 90%. As things have turned out you are overpowered by a long way but if things had been different could have been weak. When setting up the study we chose conservative power estimates and in the end the subject numbers were more than adequate. I think you should describe statistical methodology in this overall statistical section rather than in the Results section that follows. The following words were moved from the Results section to the section entitled Determination of sample size : For the unadjusted analysis the chi-square test was used. For adjusted analysis the Generalized Estimating Equations methodology was used to fit the logistic regression model to account for the clustering within families. Results Efficacy You enrolled 132 subjects. This therefore, by your own definition (received at least one treatment page 6 Treatment compliance), was the ITT group for analysis not the 123 evaluable subjects you have subsequently worked with. On a realistic analysis these should be considered treatment failures if you had no final assessment. Also you should state here and in the flow chart why these subjects were not evaluable lost to follow up, etc. Please correct all the subsequent ITT numbers and calculations where necessary.

6 We believe that assuming the 9 subjects who did not show up for the final visit for assessment are all treatment failures, introduces bias into the analysis. There is no justification for such an assumption, in our professional opinion. However, our statisticians did run the analysis, including the nine subjects who did not show up for the final assessment as treatment failures. The chi square probabilities comparing each of the two formulations against Banlice Mousse when the 9 subjects who did not appear for the final evaluation were counted as failures. We repeated the logistic regression models and found similar results compared to the analysis where the 9 subjects were excluded. Subjects in the ITT population (132 subjects in total) for whom there was no information regarding whether or not they had lice on the day after the last treatment (9 subjects), when the primary endpoint was to be determined, were included in a secondary analysis, where they were counted as failures. The results of the unadjusted chi square analysis are presented in the table below and replicate the results of initial analysis as we stated in the manuscript but now we provide the details of that analysis. Louse-Free Rate at the Day After Final Treatment including missing subjects as failures (ITT Population) P-value Number Louse-free Louse-free Percentag e Unadjuste d Louse-free rate - NeutraLice Lotion versus Banlice Mousse NeutraLice Lotion 41 out of < Banlice Mousse 10 out of Louse-free rate - NeutraLice Advance versus Banlice Mousse NeutraLice Advance 40 out of < Banlice Mousse 10 out of These additional results have been incorporated into Table 1 to satisfy the reviewer s request for inclusion. There is considerable repetition between the text and Tables 1 and 2. Do these tables really have any use? If you think tabular presentation is more important for conveying information than text then I think you should edit the text considerably to remove all fat and simplify the tables as they also have an element of repetition within them.

7 The Reviewer s suggestions have been accepted. The tabular presentation of the results have been revised. See revised Tables 1 and 2. Page 10, 2nd paragraph, 8 and 10 lines down. Surely a PP population can only consist of evaluable subjects. Please delete unnecessary words. Perhaps the Reviewer meant that the ITT population can only consist of evaluable subjects. In any case, the word evaluable was deleted in relation to mention of the ITT population in several locations. See the manuscript tracking details on page 8 & 9 of the revised manuscript. Page 10, final paragraph. I am a little confused about your analyses (which is why I requested describing the analytical methods in the Statistical management section). Surely the generalized estimating equation is used in order to avoid conducting multiple regression analysis. Can you clarify whether you ran both analyses or just one of these? For the general estimating equation the 3 treatment groups were compared simultaneously with the Banlice Mousse serving as the control. Where there were multiple subjects from the same family, family groups were identified and used as a co-variate in the generalized estimating equation to adjust for family membership. Thus, we ran both analyses simultaneously. Discussion In your Discussion you have primarily restated your observations, you have not discussed them in relation to previous findings from Australia or elsewhere and as a result we don t know how you see your results fitting into the general scheme of therapy for head lice. The Discussion section has been redrafted. The reference to previous findings has been retained (this was considered important by another reviewer), reference to the use of the shower cap and its implications and justification for the design of the study has been included. The implications of the low incidence of adverse associated with the suffocation product has also been included. Questions to consider are how much was already known, what has now been found out, whether this alters the approach to therapy, what the way forward may be in the future. See above author s response. The authors have added the following words to the Conclusion section: These results support the view that this suffocation product is as highly effective in controlling head lice as Tea Tree oil products applied under a shower cap. You should also discuss the adverse events described above in this section, as I noted above. Was the mode of application of Tea tree/lavender a contributory factor to the high AE level or is it just that essential oils are such severe irritants that you would always expect to find such outcomes when used at therapeutic concentrations? Are such AEs likely to be acceptable to the majority of users?

8 The authors have added the following words in the Discussion section: It is likely, the use of a shower cap to trap volatile components of essential oils such as Melaleuca oil and Eucalyptus oil contributes to the higher efficacy of these products as compared to the same products applied without a shower cap or older products. However, the use of a shower cap for essential oil products is also appears to be related to a higher incidence of transient and usually mild to moderate stinging, burning or erythema. Some children s skin may be more sensitive than others and for this reason the use of a suffocation type product, which retains a high degree of efficacy whilst at the same time producing a relatively low incidence of skin irritation, may be the best choice. Finally, it appears obvious to me that the pyrethrum/pbo mousse is failing to cure a high proportion of patients. I know you have not conducted any specific investigation of possible resistance in this study but I think you should at least comment upon the matter in the Discussion and speculate upon whether the data you have obtained contribute towards a meaningful debate about the future of pesticide based products. Also a discussion about whether any resistance affecting natural or synthetic pesticides is also likely to influence the outcome of treatments using other plant derived materials, like essential oils, in the near or distant future. The Reviewer s suggestion has been accepted. The following words were added to the first paragraph of the Discussion section on page 11: It is yet to be determined if head lice can or will develop resistance to either Tea Tree based products or suffocation products. Level of interest: An article whose findings are important to those with closely related research interests Quality of written English: Acceptable Statistical review: Yes, and I have assessed the statistics in my report. Declaration of competing interests: I declare that I have no competing interests

9 Reviewer's report #2 Title: A randomised, assessor blind, parallel group comparative efficacy trial of three head lice treatments in children Version: 1 Date: 16 April 2010 Reviewer: Jorg Heukelbach Reviewer's report: This an interesting study. However, the manuscript is not acceptable in its present form and needs a comprehensive and careful revision. Several major issues of basic importance when reporting clinical trials are missing and need to be included. The BMC journal recommends using the CONSORT guidelines, which in fact would be the best way to give the manuscript a clearer structure. The Reviewer s suggestions have been accepted. The major headings of CONSORT have been employed. Major Compulsory Revisions Title: Include the active substances of the products tested in the title: lavender oil, benzyl alcohol, pyrethrin The title has been amended to: A randomised, assessor blind, parallel group comparative efficacy trial of three products for the treatment of head lice in children - Melaleuca Oil and Lavender Oil, Pyrethrins and Piperonyl butoxide and a suffocation product. The authors purposely did not name the active ingredient for NeutraLice Advance because there is no identifiable active ingredient. The product acts in the physical sense and this mode of action is not attributable to any one component. The Australian Therapeutic Goods Administration has approved the sale of this product as a medical device and the official inclusion on the Australian Register of Therapeutic Goods (ARTG) for this product does not include the identification of an active ingredient either in the approved literature, product information or packaging. Full disclosure of the formulation is given in the Objectives and Interventions section on page 3 of the manuscript. Abstract: Detail information on products in abstract (x% benzyl alcohol etc.). Describe study design in more detail (topical application, no adjunctive combing, days of treatment and assessment etc). Present outcome clearly and state days of assessments: efficacy at day 1, and efficacies. Include shortly data on adverse events in the abstract. The product acts as a physical suffocation agent and as outlined in our response to the review by Dr. Ian Burgess, it does not contain a specific active ingredient. Pediculicides are topical agents, however, the word topical has been added to the second line of the abstract. We are unsure as to what the reviewer means by present outcome clearly as we believe this was made clear in the abstract. The length of the current abstract would appear to preclude the addition of further words in relation to

10 adverse effects. Methods: No information is given on the study area. I assume that the study was done in Australia, a region with many resistant head lice strains. The manuscript has been amended to state that Brisbane was the study area (see Methods, page 4, 3 rd line). No information is given if resistance of lice against pediculicides has been reported from the study area (which would reduce efficacy of pyrethrin, but not of the other products). The authors state The incidence of head louse infestation has increased in recent years [1],[2] and this may be explained by the evolution in head lice of resistance to the older popular pesticide products [3] (first sentence under Background Section page 2). The authors consider that no further information on resistance is required. Analysis of data section is missing. The heading Determination of sample size has been expanded to read Determination of sample size and data analysis as this section contains the method of data analysis ( For the unadjusted analysis the chi-square test was used. For adjusted analysis the Generalized Estimating Equations methodology was used to fit the logistic regression model to account for the clustering within families ). Pyrethrin is known to be a pediculicidal compound with relatively low efficacy. Give a clear rationale, why this product was used, and not e.g. permethrin. The pyrethrin product chosen for comparison (Banlice Mousse) was chosen because it is a market leader in Australia and the Sponsor had done a previous (unpublished) Phase 2 study using Banlice Mousse, thus giving a reliable base for the efficacy to be used in the sample size calculations. No information is given on concentration of benzyl alcohol in the respective product. Recent studies have shown high efficacy of a 5% benzyl alcohol product what is the difference of the tested product in the present study? For the sake of clarity, the product should be called benzyl alcohol product instead of suffocation product throughout the manuscript. NeutraLice Advance does contain benzyl alcohol but it is inaccurate to refer to this product as a benzyl alcohol product as stated in the response to the review by Dr. Burgess the product works via a physical action and requires all ingredients to function correctly. Full formulation details of the suffocation product are given in the manuscript. In my opinion, cure rate in one group after 8 days is not comparable with cure rate in another group after 15 days. Thus, this study did not compare efficacy different head lice products, but efficacy of different products and treatment schemes at the same time. This should be emphasized here and in the discussion. The authors have chosen to assess the efficacy of the head lice products one day after

11 the final head lice treatment for all products this was at Day 8 for Banlice Mousse and Day 15 for both NeutraLice products. The manufacturers of products consider and conduct research with regard to the development of their products and define the conditions under which their product is safe and effective. The recommended application directions including the number of applications, duration of the application, method of application (eg. under a shower cap or not) all affect the efficacy and the incidence of adverse events. It is not the responsibility of the Sponsor of another product to second guess the dosage or usage recommendations of another manufacturer. It was the Sponsor s aim to test and compare PRODUCTS Which is a function of both the formulation and the method of application as recommended by the manufacturer because, in the real world, this is how they are used. This principle applies to all therapeutic agents. When Phase 4 (post-marketing) clinical trials are conducted, dosage recommendations are not changed from that which is approved and recommended by the manufacturer. The general structure of the methods section is confusing I suggest following the structure of the CONSORT guidelines. Results: Baseline comparison between groups is missing (age, sex, hair length, prurido, severity of infestation etc.)! For the sake of conciseness, the authors attempted to spare the journal and the reviewer the detail behind the statement on page 9: Demographic factors were not found to be confounders of the effect of treatment on outcome since they were not associated with the outcome. Using a multiple logistic regression model adjusting for gender, hair length, hair type, school attended and accounting for clustering, there was still a statistically significant higher louse-free rate at the day after the final treatment among children treated with the Tea Tree/Lavender Oil product (p-value = <0.0001) and among children treated with the suffocation product (p-value = <0.0001) than among children treated with the Pyrethrins/piperonyl butoxide product. The following information was taken from the Sponsor s clinical trial report and more fully details the balance between treatment groups. We do not propose including such information into the manuscript, once again, because this level of detail is probably not sought by the journal or its readers.

12 Table Subject Demographics (ITT Population) NeutraLice Lotion n=43 NeutraLice Advance n=45 Banlice Mousse n=44 Overall n=132 P-Value Gender a Female n(%) 31 (72.1) 32 (71.1) 33 (75) 96 (72.7) 0.94 Male n(%) 12 (27.9) 13 (28.9) 11 (25) 36 (27.3) School a School Code 2 n(%) 22 (51.2) 22 (48.9) 24 (54.5) 68 (51.5) 0.99 School Code 1 n(%) 18 (41.9) 20 (44.4) 17 (38.6) 55 (41.7) School Code 3 n(%) 3 (7) 3 (6.7) 3 (6.8) 9 (6.8) Grade a c Prep n(%) 4 (9.3) 9 (20) 7 (15.9) 20 (15.2) n(%) 9 (20.9) 8 (17.8) 10 (22.7) 27 (20.5) 2 n(%) 1 (2.3) 3 (6.7) 0 4 (3) 3 n(%) 4 (9.3) 6 (13.3) 6 (13.6) 16 (12.1) 4 n(%) 7 (16.3) 4 (8.9) 6 (13.6) 17 (12.9) 5 n(%) 8 (18.6) 8 (17.8) 9 (20.5) 25 (18.9) 6 n(%) 7 (16.3) 3 (6.7) 4 (9.1) 14 (10.6) 7 n(%) 3 (7) 4 (8.9) 2 (4.5) 9 (6.8) Hair Colour a Black n(%) 16 (37.2) 27 (60) 19 (43.2) 62 (47) 0.10 Blond n(%) 10 (23.3) 6 (13.3) 4 (9.1) 20 (15.2) Brown n(%) 17 (39.5) 11 (24.4) 20 (45.5) 48 (36.4) Red n(%) 0 1 (2.2) 1 (2.3) 2 (1.5) Hair Length (cm) b N Mean SD Minimum Median Maximum Hair Length Group a Very Short (<5 cm) n(%) 7 (16.3) 6 (13.3) 4 (9.1) 17 (12.9) 0.99 Short (5 cm - <15 cm) n(%) 6 (14) 7 (15.6) 7 (15.9) 20 (15.2) Medium (15 cm - <25 cm) n(%) 2 (4.7) 4 (8.9) 4 (9.1) 10 (7.6) Long (25 cm - <45 cm) n(%) 20 (46.5) 20 (44.4) 22 (50) 62 (47) Very Long (>45 cm) n(%) 8 (18.6) 8 (17.8) 7 (15.9) 23 (17.4) Hair Type a Curly n(%) 1 (2.3) 2 (4.4) 3 (6.8) 6 (4.5) 0.59 Straight n(%) 32 (74.4) 32 (71.1) 26 (59.1) 90 (68.2) Wavy n(%) 10 (23.3) 11 (24.4) 15 (34.1) 36 (27.3) a b c Fishers Exact test used to calculate p-value ANOVA used to calculate p-value In combined classes the lower of the grade was assumed to be the grade the child came from e.g. if the grade was listed as 4/5 then the grade was assumed to be 4 All p-values are greater than 0.05 indicating there is good balance between treatment groups.

13 Figure on patient flow needs to be redrawn considering CONSORT guidelines. The different populations are a result of the patient flow and need not be presented in parallel, which is rather confusing. In the figure, include detailed information on reasons for excluding individuals (505 screened, 132 enrolled, and in addition reasons for loss to follow-up etc). The paragraph Reasons for a subject deemed not PP... does not give any quantitative information and should be deleted and data presented in this patient flow. The level of detail requested of the reviewer would appear to be incompatible with the nature of the manuscript. The reasons for exclusion of subjects were clearly indicated in the manuscript. The reason why 132 were enrolled from 505 screened is because only 132 subjects had live head lice and live head lice was the main criteria for inclusion. The reason why subjects were considered not PP are varied as shown in Table from the clinical trial report (see below). The summary of protocol deviations by treatment group is shown in Table from the clinical trial report (see below). This level of detail, we suggest, is unnecessary. What is of importance is why 123 subjects out of 132 were analysed for efficacy and this was because only 123 subjects were assessed for head lice at the end of treatment (see page 8 paragraph 2 and Figure 1). This shows 4 NeutraLice Advance subjects, 1 NeutraLice Lotion subject and 4 Banlice Mousse subjects were not available for final assessment. No subject was excluded from analysis unless they did were not available for final assessment of the trial endpoint. TABLE Summary of Subject Protocol Deviations Deviation category Type of subject protocol deviation 1 Subjects incorrectly entered into the study (incorrect inclusion / exclusion criteria) 2 Subjects who were withdrawn 0 3 Subjects who did not receive the required dose 1 4 Sibling was not treated on the same day as the 22 subject 5 Enrolled siblings did not receive the same product as 6 the original subject 6 Subjects who received prohibited head lice 7 treatments during the trial (including use of a louse comb and extremely short hair cuts) 7 Subjects failing to appear for assessment at Day 15 for NeutraLice Lotion or NeutraLice Advance or Day 8 for Banlice Mousse Total no. of deviations (all subjects) 44 Number of subjects with protocol deviations leading to categorization as not-per- Protocol 0 8 TABLE Summary of protocol deviations by treatment group Treatment group No. of subjects with protocol deviations NeutraLice Lotion 12 NeutraLice Advance 10 Banlice Mousse 22 Total no. of deviations (all subjects) 44 Confidence intervals of cure rates and effect size calculations are missing.

14 We have consulted with the trial statistician, Dr. Jim Sockler of Datapharm Australia and his response is that the statistical approach was to look for differences between treatments rather than generate predictive models. Additional analyses are missing (efficacy stratified by subgroups age, sex, length of hair, severity of infestation) and should be presented. Important secondary outcome measures usually reported in head lice trials (such as pruritus, clinical data/excoriation/pyoderma etc.) are missing. The clinical trial statistician has advised that the groups are too small to produce any meaningful outcome for such an analysis. There were no incidents of pruritus, excoriation or pyoderma. Some methods are presented in this section these should be moved to the Methods section. Description of adverse events is confusing. Give exact figures of number, type and severity of adverse events. In addition, I cannot imagine that there have been only adverse events related with the treatment. Please report also number and type of unrelated adverse events. Figures as to the number, type and severity of adverse events were provided in the manuscript on pages Adverse events were only reported as related to treatment. Demographic factors were not found to be confounders... : present detailed results of the logistic regression model. Include description of regression analysis in the methods section. Tables: to improve clarity, include data of all assessments in the tables (days 1, 8, 15) and make clear the day and assessment method (dry or wet combing). Include 95% CI and effect size. Do not present redundant information (data on comparison group is presented twice in both tables). The Tables of results have been modified to reduce redundant information and consolidated (see revised tables 1 & 2). Confidence intervals were not calculated as previously indicated. Discussion: The discussion is insufficient. Limitations of the study are not discussed (such as sources of bias, use of different observation periods between groups, different treatment of family members, no comparison with gold standard, dry combing at one assessment and wet combing at the other, use of visual inspection without combing would decrease cure rates in heavy infestation etc.) The Discussion section has been redrafted. The reference to previous findings has been retained (this was considered important by another reviewer), reference to the use of the shower cap and its implications and justification for the design of the study has been included. The implications of the low incidence of adverse associated with the suffocation product has also been included. See revised Discussion section with

15 tracking notes (page 10). Banlice Mousse is a reasonable gold standard for the purposes of our trial because as this product has been a leading brand in Australia for over 20 years. As said before, a drawback is the fact that one group was combed out on days 1 and 8, the other on days 1 and 15. I understand the authors rationale for doing so, but this does not make a lot of sense when comparing two treatments. This issue should be discussed in the manuscript. The reviewer does not make the distinction between dry combing on the day after the first application in all treatment groups (Day 1) and the assessment Day (either Day 8 for Banlice Mousse or Day 15 for the NeutraLice products). The dry combing conducted at Day 1 is a detection method which is designed specifically to have little impact on the population of live lice in the hair of the subject if present. Whereas the wet combing is a comprehensive combing technique designed to detect any live lice present but this technique has the effect of removing live lice. However, once live lice are detected using wet combing at the end of the study, it does not matter if the live lice are removed by this technique as the end result is obtained. We respectfully suggest to the editor that the reviewer has not appreciated the difference and use of the two combing techniques in head lice studies. The use of the two techniques is essential to compare the treatments to gauge an immediate effect and the ultimate lice killing effect at the end of treatment (efficacy of the product). Discussion of validity is missing. Interpretation of results should take into account other recent trials on suffocation and other products which are not mentioned. In the past few years, there have been published several trials on these new approaches which should be adequately discussed and compared to data of the present study (such as spinosad, ivermectin, dimeticone products). The Discussion section was limited to contrasting the published efficacy of similar products (Tea Tree oil and suffocation products). There are numerous classes of pediculicides and a discussion of further classes is considered beyond the scope of the Discussion. Discuss resistance issues (probable cause of low efficacy of pyrethrin). Mode of action of suffocation products should be discussed in more detail, as this the reason why these products most probably are not susceptible for development of resistance (see ref. 5 and 2 other papers published recently on the mode of action on dimeticones). Please see last line of revised Discussion section. Do not repeat detailed results data in discussion. Level of interest: An article of importance in its field Quality of written English: Acceptable Statistical review: No, the manuscript does not need to be seen by a statistician. Declaration of competing interests: I do not have commercial links with any of the producers of the pediculicides tested in this study, but have been scientific consultant to other producers of pediculicidal products.

16 Reviewer's report #3 Title: A randomised, assessor blind, parallel group comparative efficacy trial of three head lice treatments in children Version: 1 Date: 4 May 2010 Reviewer: Maria Picollo Reviewer's report: The manuscript analyses the efficacy of three head lice commercial products in 4-12 years-old children. The results and the methodology described in the article represent important contributions for the clinical research of the pediculicide formulations. The objectives of the work are clearly exposed and adequate for the scope of the journal. The methodologies are carefully described and are appropriated for the objectives. The title and the abstract exactly refer to the finding of the manuscript. The discussion and conclusions are in accordance with the results of the work. There are not grammar problems. There are three minor recommendations to improve the understanding of the work: 1) Methods, objectives. The authors described the head lice treatment products used in the clinical trial. The concentration of the active ingredients are well indicated in the product containing essential oils (10% Tea Tree oil and 1% Lavender oil), and in the product containing insecticide (1,65 mg/g pyrethrins and 16,5 mg/g piperonyl butoxide). However the concentrations of the active ingredients in suffocation product are missed. I suggest including this missing information for the best description of all the head lice products used in the comparative trial. The authors purposely did not name the active ingredient for NeutraLice Advance because there is no identifiable active ingredient. The product acts in the physical sense and this mode of action is not attributable to any one component. The Australian Federal Government regulatory agency (the Australian Therapeutic Goods Administration) has approved the sale of this product as a medical device and subsequently included this product on the Australian Register of Therapeutic Goods (ARTG) since this product does not include the identification of an active ingredient either in the approved literature, product information or packaging. Full disclosure of the formulation is given in the Objectives and Interventions section on page 3 of the manuscript. 2) Methodology, Dosage and dosage regimen The authors indicated that the doses, method of application and number of weekly treatments were those recommended by the manufactures. They added that after the application of the Tea Tree/ Lavender Oil and the suffocation products, the hair was washed with water. The majority of the suffocation products in the international market are difficult to wash out the hair and generally two shampoo washes are recommended. Please, verify that shampoo was not used for washing out the suffocation product. The authors confirm that shampoo was not used for washing out the suffocation product or the Tea Tree Oil/Lavender Oil product.

17 3) Figure 1, Table 1 and Table 2, are duplicated in the document The two tables have been revised (see tables 1 & 2).