An examination of the observed placebo effect associated with the treatment of low back pain - a systematic review.

OBJECTIVE: To determine whether the nonspecific effects that occur following the use of sham interventions to treat nonspecific low back pain (LBP) are large enough to be considered clinically meaningful.
DESIGN: Electronic databases were searched systematically for randomized placebo-controlled trials of interventions for LBP that used sham ultrasound, sham laser or sham drug therapy as the placebo control. Study selection was accomplished via independent evaluation of scientific admissibility by three reviewers and final decisions of inclusion were based on consensus.
RESULTS: None of the studies using sham ultrasound as the placebo control in the treatment of LBP were acceptable for inclusion. Twelve studies were included in the present evaluation of the placebo effect - eight trials that met the strict inclusion criteria for best evidence (three using sham laser placebo and five using sham medication placebo) and four sham medication studies that 'just missed' the inclusion criteria for best evidence. Although the evidence from studies using sham laser was inconclusive, the present review did find a clinically meaningful change in LBP scores following the use of sham oral medications.
CONCLUSIONS: The present best-evidence review found a clinically meaningful change in pain scores following the use of sham oral medications for the treatment of nonspecific LBP. This finding suggests that further clinical research is warranted to identify which patient subgroups could benefit most from such treatment and to distinguish the true contribution of the placebo effect from other nonspecific effects.