title: Dose response and efficacy of spinal manipulation for chronic cervicogenic headache: a pilot randomized controlled trial.
abstract: BACKGROUND
  Systematic reviews of randomized controlled trials suggest that spinal manipulative therapy (SMT) is efficacious for care of cervicogenic headache (CGH). The effect of SMT dose on outcomes has not been studied.
  
  
  OBJECTIVE
  To compare the efficacy of two doses of SMT and two doses of light massage (LM) for CGH.
  
  
  METHODS
  Eighty patients with chronic CGH.
  
  
  METHODS
  Modified Von Korff pain and disability scales for CGH and neck pain (minimum clinically important difference=10 on 100-point scale), number of headaches in the last 4 weeks, and medication use. Data were collected every 4 weeks for 24 weeks. The primary outcome was the CGH pain scale.
  
  
  METHODS
  Participants were randomized to either 8 or 16 treatment sessions with either SMT or a minimal LM control. Patients were treated once or twice per week for 8 weeks. Adjusted mean differences (AMD) between groups were computed using generalized estimating equations for the longitudinal outcomes over all follow-up time points (profile) and using regression modeling for individual time points with baseline characteristics as covariates and with imputed missing data.
  
  
  RESULTS
  For the CGH pain scale, comparisons of 8 and 16 treatment sessions yielded small dose effects: |AMD|</=5.6. There was an advantage for SMT over the control: AMD=-8.1 (95% confidence interval=-13.3 to -2.8) for the profile, -10.3 (-18.5 to -2.1) at 12 weeks, and -9.8 (-18.7 to -1.0) at 24 weeks. For the higher dose patients, the advantage was greater: AMD=-11.9 (-19.3 to -4.6) for the profile, -14.2 (-25.8 to -2.6) at 12 weeks, and -14.4 (-26.9 to -2.0) at 24 weeks. Patients receiving SMT were also more likely to achieve a 50% improvement in pain scale: adjusted odds ratio=3.6 (1.6 to 8.1) for the profile, 3.1 (0.9 to 9.8) at 12 weeks, and 3.1 (0.9 to 10.3) at 24 weeks. Secondary outcomes showed similar trends favoring SMT. For SMT patients, the mean number of CGH was reduced by half.
  
  
  CONCLUSIONS
  Clinically important differences between SMT and a control intervention were observed favoring SMT. Dose effects tended to be small.
authors.affiliation: Center for Outcomes Studies, Western States Chiropractic College, 2900 NE 132nd Ave., Portland, OR 97230, USA. mhaas@wschiro.edu
authors.forename: Mitchell
authors.initials: M
authors.lastname: Haas
authors.forename: Adele
authors.initials: A
authors.lastname: Spegman
authors.forename: David
authors.initials: D
authors.lastname: Peterson
authors.forename: Mikel
authors.initials: M
authors.lastname: Aickin
authors.forename: Darcy
authors.initials: D
authors.lastname: Vavrek
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D005260:Female; D006801:Humans; D057194:Intention to Treat Analysis; D008297:Male; D020393:Manipulation, Spinal; D008875:Middle Aged; D019547:Neck Pain / Q000628:therapy*; D016017:Odds Ratio; D010147:Pain Measurement; D010865:Pilot Projects; D051298:Post-Traumatic Headache / Q000628:therapy*; D012720:Severity of Illness Index; D013997:Time Factors; D016896:Treatment Outcome