Statistics from Altmetric.com
Editor,—We congratulate Olafsdottiret al on their article.1 The sum of the evidence on spinal manipulative therapy (SMT) in the treatment of infantile colic now is that there are 3 randomised controlled trials (RCTs) on the subject.
Two RCTs demonstrated a significant positive effect of SMT,2 3 and 1 RCT was unable to demonstrate any treatment effect.1 The reasons for this discrepancy are not known, but Olafsdottir et al suggest that their finding of no effect of SMT may be due to the blinding of the infants' mothers. Another equally likely explanation could be that we are witnessing a dose response phenomenon.
In their trial, Olafsdottir et al used a treatment protocol of a maximum of 3 sessions of SMT, whereas the other 2 RCTs, which found a positive treatment effect, used a treatment protocol relying more on the treating chiropractor's clinical judgement. This more pragmatic approach resulted in 64% of the infants in one RCT receiving 4 or more sessions of SMT (with a maximum of 7),2 and the majority of infants in the other RCT receiving up to 6 sessions.3
We believe that this dose response problem should be addressed in future trials of SMT for infantile colic.