Potential effect modifiers for treatment with chiropractic manipulation versus sham manipulation for recurrent headaches in children aged 7-14 years: development of and results from a secondary analysis of a randomised clinical trial.

"Declarations Ethics approval and consent to participateAll parents were required to give written informed consent allowing their child to participate in this study and they were informed orally and in writing that participation in the trial was voluntary and that parents could withdraw their child from the trial at any time with no negative consequences for the child. All participants were treated according to the Declaration of Helsinki [40]. The project was approved by the Regional Committee on Health Research Ethics for the Region of Northern Denmark (#N-20150025) and data were handled according to the General Data Protection Regulations [41]. The trial was registered with ClinicalTrials.gov (Identifier: NCT02684916) [42]. Consent for publicationNot applicable. Competing interestsLH, KBD, WV and HWC are supported partly by the Foundation for Chiropractic Research and Postgraduate Education; SL, HWC and KBD are in private practice, treating the patients in question. There are no other relationships or activities that could appear to have influenced the submitted work. Competing interests LH, KBD, WV and HWC are supported partly by the Foundation for Chiropractic Research and Postgraduate Education; SL, HWC and KBD are in private practice, treating the patients in question. There are no other relationships or activities that could appear to have influenced the submitted work."

"Funding Open access funding provided by University Library of Southern Denmark. The study was primarily funded by the Foundation for Chiropractic Research and Postgraduate Education (Grant no 09/2518). The Danish Migraine and Headache Society also made a financial contribution. The funding bodies did not have any influence on the study design; in the collection, analysis, and interpretation of data; in the writing of the report; or in the decision to submit the article for publication. All authors had full access to all data (including statistical reports and tables) in the study and can take responsibility for the integrity of the data and the accuracy of the data analysis."

"Trial registration : ClinicalTrials.gov (Albers et al in Curr Pain Headache Rep 19:3–4, 2015), identifier NCT02684916, registered 02/18/2016—retrospectively registered."