In the October 2014 publication of JAMA, Dr. Hinman and colleagues published the study “Acupuncture for Chronic Knee Pain: A Randomized Clinical Trial,” which concluded that “in patients older than 50 years with moderate or severe chronic knee pain, neither laser nor needle acupuncture conferred benefit over sham for pain or function. Our findings do not support acupuncture for these patients.” As pointed out in my former article, Part I, there were serious flaws in the trial design and statistics, as well as in the interpretation of the results. This article attempts to address problems in the Zelen design used by Hinman et al. There are some advantages to using a Zelen design for a randomized controlled trial (RCT). First, a Zelen design has a post-randomization consent design, which means that consent is only sought for one treatment each time, without the uncertainty of randomization. Researchers can be more comfortable knowing that they have the participants’ consent each time they undergo a treatment. Patients can also be more comfortable with this design because they know which type of treatment they are receiving; unlike traditional RCTs, patients are not ignorant of whether they are receiving the placebo or experimental treatment. Effects such as resentful demoralization and what is known as the “Hawthorne effect” (altered behavior or performance resulting from awareness of being a part of an experimental study) become less of an issue as patients are not weary of being part of a new alternative group, only the “standard” therapy will applies to them. However, it does have some disadvantages, and therefore can cause biases.
1 High drop-out rate:
The drop-out rates were 2.82% (2/71) in the control group; 22.86% (16/70) in the acupuncture group; 18.31% (13/71) in the laser acupuncture group; and 22.86% (16/70) for the sham laser acupuncture group. According to the acceptable standards for an RCT, dropout rates less than 10% are acceptable, drop-out rates between 10% and 20% mean that the resulting data quality is poor, and drop-out rates of more than 20% mean that the data quality is considered very poor and should not be used in analysis. In this trial analysis, the data quality in the acupuncture and sham laser acupuncture groups are very poor as the drop-out rates are over 20%; the authors should not have directly used them in any statistical analysis, unless they had re-adjusted and re-balanced the sample among the groups during the study. As outlined by the National Institutes of Health, if there is a differential drop-out rate of 15% or higher between study arms, such as between the control group and the treatment group in this clinical trial, then there is a very high potential for bias. This is a flaw that can decrease the quality of the study results.
2 The effectiveness in intervention groups was diluted by various factors
The dilution rates should then be 21.87% in the laser acupuncture group, 13.80% in the sham laser acupuncture group, and 31.27% in the acupuncture group (the dilution rate calculations were shown in Tables 1–3). The dilution rate was very significant in the acupuncture group, which causes the effectiveness to be undervalued in the acupuncture group, by almost 1/3.
The effective significance was masked by limited sample size due to the Zelen design of this study.
3.The sample size calculation in this study is questionable.
4 Conclusion The effectiveness of the acupuncture group was diluted 31.27%, and its drop-out rate was 22.86%, much higher than that of the other groups in Hinman’s clinical trial, which constitutes major flaws in how this study is analyzed and interpreted. Based on the bias of Zelen design used in the study, and incorrect sample size calculation, the conclusions drawn from this study are of poor quality, inaccurate, and invalid.
1 Hinman RS, McCrory P, Pirotta M, Relf I, Forbes A, Crossley KM, Williamson E, Kyriakides M, Novy K, Metcalf BR, Harris A, Reddy P, Conaghan PG, Bennell KL. Acupuncture for chronic knee pain: a randomized clinical trial. JAMA. 2014; 312(13): 1313–1322.
2 Fan AY. The methodology flaws in Hinman’s acupuncture clinical trial, Part I: Design and results interpretation. J Integr Med. 2015; 13(2): 65–68.