We talk over and over about the importance of removing bias from clinical trials. There is financial and ideological biases that can distort the results of a trial by innumerable, often subconscious, ways.

There is also the bias that creeps into a trial if the patient is not blinded to the intervention in a clinical trial.

The two characteristics that determine if acupuncture is reported as effective are 1) if the patient thinks they are getting acupuncture and 2) if they believe acupuncture is effective.

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If patients are unaware or do not believe, then acupuncture does not work. And, of course, that is only for subjective, patient reported, outcomes. For objective outcomes acupuncture, like other pseudo-medical interventions, does nothing.

This consistent finding is emphasized in Bias due to lack of patient blinding in clinical trials. A systematic review of trials randomizing patients to blind and nonblind sub-studies.:

The average difference in effect size for patient-reported outcomes was –0.56 (95% confidence interval –0.71 to –0.41), (I2 = 60%, P = 0.004), i.e. nonblinded patients exaggerated the effect size by an average of 0.56 standard deviation, but with considerable variation… There was a larger effect size difference in 10 acupuncture trials [–0.63 (–0.77 to –0.49)], than in the two non-acupuncture trials [–0.17 (–0.41 to 0.07)].

Patient who know they are getting acupuncture report better results than those who are blinded. More data to suggest that the effects of acupuncture are due to an elaborate ritual rather than actual physiologic effects. They cause the patient to report they are better when in fact they are not. Yes, I know, are they not better if they report they are better? Kind of a koan. Think of acupuncture as beer goggles: it does not change reality, just the perception of it.

As the researcher conclude:

This study provides empirical evidence of pronounced bias due to lack of patient blinding in complementary/alternative randomized clinical trials with patient-reported outcomes.

Those who aggressively question the reality of pseudo-medicine are often accused of being in the pocket of Big Pharma. Not so. And at least we are aware enough be avoid the consequences of Big Bias.