Methods: A randomized clinical trial was conducted with a factorial design in which adult TTH sufferers with more than 10 headaches per month were randomly assigned to four groups: real cervical manipulation + real amitriptyline, real cervical manipulation + placebo amitriptyline, sham cervical manipulation + real amitriptyline, and sham cervical manipulation + placebo amitriptyline. A baseline period of four weeks was followed by a treatment period of 14 weeks. The primary outcome was headache frequency obtained from a headache diary in the last 28 days of the treatment period.
Results: Nineteen subjects completed the trial. In the unadjusted analysis, a statistically significant main effect of chiropractic treatment was obtained (−2.2 [−10.2 to 5.8], P = .03) which was just below the 3-day reduction set for clinical importance. As well, a clinically significant effect of the combined therapies was obtained (−9 [20.8 to 2.9], P = .13), but this did not achieve statistical significance. In the adjusted analysis, neither the main effects of chiropractic nor amitriptyline were statistically significant or clinically important; however, the effect of the combined treatments was −8.4 (−15.8 to −1.1) which was statistically significant (P = .03) and reached our criterion for clinical importance.
Conclusion: Although the sample size was smaller than initially required, a statistically significant and clinically important effect was obtained for the combined treatment group. There are considerable difficulties with recruitment of subjects in such a trial. This trial should be replicated with a larger sample.
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