How large are the nonspecific effects of acupuncture? A meta-analysis of randomized controlled trials
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vor 14 Jahren
Background: While several recent large randomized trials found
clinically relevant effects of acupuncture over no treatment or
routine care, blinded trials comparing acupuncture to sham
interventions often reported only minor or no differences. This
raises the question whether (sham) acupuncture is associated with
particularly potent nonspecific effects. We aimed to investigate
the size of nonspecific effects associated with acupuncture
interventions. Methods: MEDLINE, Embase, Cochrane Central Register
of Controlled Clinical Trials and reference lists were searched up
to April 2010 to identify randomized trials of acupuncture for any
condition, including both sham and no acupuncture control groups.
Data were extracted by one reviewer and verified by a second.
Pooled standardized mean differences were calculated using a random
effects model with the inverse variance method. Results:
Thirty-seven trials with a total of 5754 patients met the inclusion
criteria. The included studies varied strongly regarding patients,
interventions, outcome measures, methodological quality and effect
sizes reported. Among the 32 trials reporting a continuous outcome
measure, the random effects standardized mean difference between
sham acupuncture and no acupuncture groups was -0.45 (95%
confidence interval, -0.57, -0.34; I-2 = 54%; Egger's test for
funnel plot asymmetry, P = 0.25). Trials with larger effects of
sham over no acupuncture reported smaller effects of acupuncture
over sham intervention than trials with smaller nonspecific effects
(beta = -0.39, P = 0.029). Conclusions: Sham acupuncture
interventions are often associated with moderately large
nonspecific effects which could make it difficult to detect small
additional specific effects. Compared to inert placebo
interventions, effects associated with sham acupuncture might be
larger, which would have considerable implications for the design
and interpretation of clinical trials.
clinically relevant effects of acupuncture over no treatment or
routine care, blinded trials comparing acupuncture to sham
interventions often reported only minor or no differences. This
raises the question whether (sham) acupuncture is associated with
particularly potent nonspecific effects. We aimed to investigate
the size of nonspecific effects associated with acupuncture
interventions. Methods: MEDLINE, Embase, Cochrane Central Register
of Controlled Clinical Trials and reference lists were searched up
to April 2010 to identify randomized trials of acupuncture for any
condition, including both sham and no acupuncture control groups.
Data were extracted by one reviewer and verified by a second.
Pooled standardized mean differences were calculated using a random
effects model with the inverse variance method. Results:
Thirty-seven trials with a total of 5754 patients met the inclusion
criteria. The included studies varied strongly regarding patients,
interventions, outcome measures, methodological quality and effect
sizes reported. Among the 32 trials reporting a continuous outcome
measure, the random effects standardized mean difference between
sham acupuncture and no acupuncture groups was -0.45 (95%
confidence interval, -0.57, -0.34; I-2 = 54%; Egger's test for
funnel plot asymmetry, P = 0.25). Trials with larger effects of
sham over no acupuncture reported smaller effects of acupuncture
over sham intervention than trials with smaller nonspecific effects
(beta = -0.39, P = 0.029). Conclusions: Sham acupuncture
interventions are often associated with moderately large
nonspecific effects which could make it difficult to detect small
additional specific effects. Compared to inert placebo
interventions, effects associated with sham acupuncture might be
larger, which would have considerable implications for the design
and interpretation of clinical trials.
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