Author's response to reviews Title: Prognostic factors for non-success in patients with sciatica and disc herniation Authors: Anne J Haugen (annhau@so-hf.no) Jens I Brox (j.i.brox@medisin.uio.no) Lars Grovle (largro@so-hf.no) Anne Keller (akel0008@regionh.dk) Bard Natvig (bard.natvig@medisin.uio.no) Dag M Soldal (dag.magnar.soldal@sshf.no) Margreth Grotle (margreth.grotle@medisin.uio.no) Version: 3 Date: 23 August 2012 Author's response to reviews: see over
Response to reviewer 1 Reviewer's report Title: Prognostic factors for non-success in patients with sciatica and disc herniation Version: 2 Date: 19 June 2012 Reviewer: Alice Kongsted Reviewer's report: I would like to compliment you for the substantial improvements of the paper and to thank for the detailed responses to my comments. I still have a comment regarding surgery as prognostic factor. I apologize if my comment to this issue was unclear, but I think the specific limitations in relation to this prognostic factor should be discussed. Among those who did not recover some had surgery (mainly within the first 3 months), whereas others had no surgery. It seems likely that patients who were offered to have an operation had more clear-cut symptoms when the decision about surgery was made (e.g. pain in the relevant dermatome, disc degeneration only on one disc level, less psychological involvement) than those who had no surgery despites non-recovery. This cannot be adjusted for by including baseline covariates, and I think it ought to be mentioned as a limitation that it was not possible to adjust the surgery variable for symptom and signs at the time when it was decided to operate. We have added to the discussion more about the limitations in relation to use the surgical variable as a prognostic factor. This variable is complex because it contains both the decision regarding surgery and the fact that surgery was performed, hence, it is not possible to adjust the variable for symptoms and signs at the time it was decided to operate the patient. This might influence the interpretation of the results of the surgical treatment. Because of this shortcoming I would be careful to describe the effect of surgical treatment as independently related to outcome. I would rather state that it had an association with outcome, which was not explained by differences in the measured baseline variables. We have changed higher risk of to association with in the discussion: For the main outcome, males, smokers, patients with higher scores for low back pain and patients who had not undergone surgery had an independent association with non-success at 1 year, but not at 2 years of follow-up. We also discuss the surgery variable later in the discussion, and we do not use
the wording effect of surgical treatment, but we describe the association. A minor issue in the 1st paragraph of the discussion section: A high score for comorbid subjective health complaints was the only variable that predicted nonsuccess at both 1 and 2 years I suggest that you specify that this was for the multivariabel models. We have now added For the multivariable models, to the text. 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 declare that I have no competing interests Response to reviewer 2 Reviewer's report Title: Prognostic factors for non-success in patients with sciatica and disc herniation Version: 2 Date: 24 June 2012 Reviewer: Eva Skillgate Reviewer's report: Discretionary Revisions (which are recommendations for improvement but which the author can choose to ignore) One of my previous comments was: Having the self-reported health status variables as continuous variable in the model makes them hard to interpret and compare. One way to deal with this could be to divide the scores with the maximum value. This would make the OR s higher, comparable and more meaningful. I did not at all ask you to dichotomize them all, as the authors did. A agree that a dichotomization is not the best way to perform. Working with the previous revision, we did not do the recalculation correctly (we multiplied the new variable with 100) and ended up with the same results as before the transformation of the values. Therefore, we thought the recommendation was to do a dichotomization, which we agree is not the best way to present the results. Minor Essential Revisions (such as missing labels on figures, or the wrong use of a term, which the author can be trusted to correct)
Major Compulsory Revisions (which the author must respond to before a decision on publication can be reached) I had some comments on the abstract but I cannot find an abstract in the revised manuscript. The abstract was uploaded elsewhere in the revision submitting process. If the abstract was not added, we apologize for that. We did some changes in the abstract in the first revised manuscript, and we will carefully add the abstract to this revision. We have changed all OR s and CI s to two decimals. The expression sciatica-specific clinical findings is now removed from the abstract, but defined in the Methods: The sciatica-specific clinical assessment included.. Level of interest: An article of importance in its field Quality of written English: Acceptable Statistical review: Yes, but I do not feel adequately qualified to assess the statistics. Declaration of competing interests: 'I declare that I have no competing interests' Response to reviewer 3 Reviewer's report Title: Prognostic factors for non-success in patients with sciatica and disc herniation Version: 2 Date: 22 June 2012 Reviewer: Susan Picavet Reviewer's report: The paper has improved substantially. Three remarks: - Introduction: The sentence Most patients recover with conservative treatment, but a minority of patients requires surgery [3, 6] is a bit puzzling with nearly 70% had persistent sciatica symptoms 13 years later. Better is to say something like: Most patients receive conservative treatment, and a minority of patients undergoes surgery [3, 6] We have now changed the sentence to Most patients receive conservative treatment, and a minority of patients requires surgery. - Methods: I do not understand what is meant with: To compensate for the missing items in questionnaires, the missing items were substituted with the
arithmetic mean of the values from the available items in the questionnaire for each respondent. The text is changed to To compensate for missing items in a questionnaire, the missing item was substituted with the arithmetic mean of the actual respondent s available item values. - General: the text seems rather long and long-winded. The readability might improve when it is a bit more concise. We have removed som text. From the Methods: The self reported questionnaires were only completed by the study patients. is taken out because this is described in Procedure. The total score is calculated by adding all scores and dividing the sum by the number of completed items. is changed to The score is calculated as the mean of the completed items. At inclusion, a clinical examination was carried out by a physiotherapist or physician. is removed because this is also mentioned in Procedure. The clinical examination of the patient was part of their usual care is also removed because it is described in Cohort selection and recruitment: Hence, patients received the usual consultations including a clinical examination, information The questionnaires were sent to the participants at 3, 6, 12 and 24 months. is removed because it is described in Procedure. The following text is removed: We found an interaction effect between smoking and surgery. The interpretation of that finding could be that the association between non-surgical treatment and non-success differs for smokers and nonsmokers. The text is replaced by: The interpretation of the interaction effect between smoking and surgery might be that the association between (non-) surgical treatment and (non-)success differs for smokers and non-smokers. The sentence A possible explanation for this is that in the final multivariate model at 2 years, the sciatica-specific symptoms had lost importance. has ben removed and the meaning is changed to: Comorbidity, kinesiophobia, and duration of symptoms at baseline were associated with non-success at the 2-year follow-up and may indicate that psychosocial factors are more important for the long-term prognosis than sciatica specific symptoms and disability.
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 declare that I have no competing interests