Bias

Bias

recently mentioned the issues of bias in the medical literature and suggested that belief in a pseudo-medical intervention may be every bit as distorting as a financial interest in an outcome. A postive study of acupuncture by acupuncturists should be as suspect as a pharmaceutical sponsored drug study.

It has long been suggested that Asian countries only publish positive results for acupuncture:

Research conducted in certain countries was uniformly favorable to acupuncture; all trials originating in China, Japan, Hong Kong, and Taiwan were positive.

and this trend is confirmed in Positive Results in Randomized Controlled Trials on Acupuncture Published in Chinese Journals: A Systematic Literature Review. In acupuncture trials from China, acupuncture is virtually always found superior or equal to conventional therapy:

A total of 840 RCTs with 71,871 participants were identified, including 727 RCTs comparing acupuncture with conventional treatment, 51 RCTs with no treatment, and 62 RCTs with sham-acupuncture. Among them, 838 trials (99.8%) reported positive results from primary outcomes, while only two trials (0.2%) reported negative results, comparing acupuncture with conventional treatment and sham-acupuncture respectively. Among the 726 RCTs comparing acupuncture with conventional treatment, 641 trials (88.3%) favored acupuncture groups;While 85 trials (11.7%) showed no significant difference between acupuncture and conventional treatment groups, the authors concluded positive results based on the findings.

Bias is a hard thing to overcome and is often unrecognized by those doing a clinical study and can distort the results. My favorite example is the study where acupuncture was credited with improved stroke outcomes even thought the acupuncture group was more likely to be taking conventional stroke prevention medications.

If you judge a study by the company it keeps, I would take a positive acupuncture study from China with a grain of salt substitute.  A favorable outcome is likely due to bias or poor study design.

For more see Evidence Update-Chinese Studies of Acupuncture Are Always Positive: Perfect Medicine or Hidden Bias?.

Points of Interest 5/23/2014
Points of Interest 5/22/2014