Setting and participants
musculoskeletal dysfunction, headache
RECRUITMENT
The RCT was conducted in two clinics in Northern Denmark between November 2015 and April 2020. Invitations were sent through the Danish School Information Network, local newspapers, television, social media, and radio. Screening and treatments were administered by the investigating chiropractor with 34 years of experience in paediatric private practice. Children aged 7–14 years of age were invited to participate if they had suffered from headache for at least half a year with a minimum of one episode of headache per week, and in addition the investigating chiropractor had to be able to identify at least one musculoskeletal dysfunction in the spine, pelvis and/or temporomandibular joint. Exclusion criteria were contraindications to spinal manipulation, red flags requiring referral to other types of health care at the initial screening visit, other treatments for headache within the past three months, or failure to report pre-randomization baseline data.The recruitment process included a detailed baseline questionnaire prior to start of a four-week pre-treatment phase. The translated version of this questionnaire is provided in Additional file 