Archived Comments for:
Managing stress and anxiety through qigong exercise in healthy adults: a systematic review and meta-analysis of randomized controlled trials
More suitable for a qualitative analysis than a meta-analysis
Guang-Hua Lei, Xiangya Hospital, Central South University
11 February 2014
Dear Editors,
We have read with interest the recent report by Wang and coworkers [1] on managing stress and anxiety through qigong exercise in healthy adults. In a systematic review and meta-analysis of earlier randomized controlled trials, the authors conclude to a significant effect of qigong exercise in pooled stress and anxiety for healthy adults based on data from 199 cases and 199 controls. We really appreciate the work which was done by the authors. At a closer look, however, the positive finding loses its luster.
Firstly, data were extracted by one main researcher and then verified by another researcher. Any discrepancies were resolved by discussion. However, in this process it caused selector bias of the meta-analysis, because data extraction of the second researcher was not blind and independent [2]. Previous studies showed that the odds of error caused by two authors extracting data independently was reduced significantly, compared with data extraction twice successively [3]. Meanwhile, cochrane handbook suggest professionals of different background extract data, such as an epidemiologist and a clinical expert, to ensure avoiding selection bias [4].
Secondly, the authors indicated that crossover RCTs were excluded because their results are subject to carryover bias. But in the analysis of effects of qigong exercise, the included study of Chow et al. [5] and Hwang et al. [6] were both crossover RCTs on anxiety and perceived stress, which also cause carryover bias. Thus, we are not sure whether the two missing RCTs excluded because of crossover should have been retrieved in or not.
Finally, Seven RCTs met the inclusion criteria. They were conducted in different countries and the characteristics of participants varied in different studies such as age, intervention (frequency), control, duration and relevant outcome measures. As limited number of included studies, especially the differences between research methods, it is not suitable for meta-analysis but qualitative analysis, in order to avoid merging the same kind of research with different results and losing credibility [7].
On the whole, this meta-analysis raises more questions than it answers. To facilitate future assessments of qigong exercise in stress and anxiety, we invite the authors to improve the research that is required to put into perspective the qigong exercise they have recently contributed for stress and anxiety.
Above all, we respect the great contributions of the authors and we are pretty sure the results of the data analysis are accurate with no doubt.
Reference
[1] Wang, C. W., Chan, C. H., Ho, R. T., Chan, J. S., Ng, S. M., & Chan, C. L. (2014). Managing stress and anxiety through qigong exercise in healthy adults: a systematic review and meta-analysis of randomized controlled trials. BMC Complement Altern Med, 14(1), 8. doi: 10.1186/1472-6882-14-8.
[2] Felson, D. T. (1992). Bias in meta-analytic research. J Clin Epidemiol, 45(8), 885-892.
[3] Meade, M. O., & Richardson, W. S. (1997). Selecting and appraising studies for a systematic review. Ann Intern Med, 127(7), 531-537.
[4] Higgins JPT, Green S (editors). Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 [updated March 2011]. The Cochrane Collaboration, 2011. Available from www.cochrane-handbook.org.
[5] Chow, YvonneW.Y., Dorcas, Allen, & Siu, AndrewM.H. (2012). The Effects of Qigong on Reducing Stress and Anxiety and Enhancing Body–Mind Well-being. Mindfulness, 3(1), 51-59. doi: 10.1007/s12671-011-0080-3.
[6] Hwang, E. Y., Chung, S. Y., Cho, J. H., Song, M. Y., Kim, S., & Kim, J. W. (2013). Effects of a brief Qigong-based stress reduction program (BQSRP) in a distressed Korean population: a randomized trial. BMC Complement Altern Med, 13, 113. doi: 10.1186/1472-6882-13-113.
[7] O'Sullivan, E. M., & Higginson, I. J. (2010). Clinical effectiveness and safety of acupuncture in the treatment of irradiation-induced xerostomia in patients with head and neck cancer: a systematic review. Acupunct Med, 28(4), 191-199. doi: 10.1136/aim.2010.002733.
Competing interests
No competing interests exist.
Response to Lei's comments on "Managing stress and anxiety through qigong exercise in healthy adults: a systematic review and meta-analysis of randomized controlled trials"
Chong-Wen Wang, The University of Hong Kong
27 June 2014
Dear Editors:
We have noted the comments [1] given by Dr. Lei on our recent article: "Managing stress and anxiety through qigong exercise in healthy adults: a systematic review and meta-analysis of randomized controlled trials" [2]. In his correspondent, he raised a concern about selection bias in our review and stated that "the included study of Chow et al. [3] and Hwang et al. [4] were both crossover RCTs (randomized controlled trials) on anxiety and perceived stress." We thank Dr. Lei for his opinion, but disagree to his statement. According to Sibbald and Roberts [5], crossover RCT is a longitudinal study in which subjects are randomly allocated to study arms where each arm consists of a sequence of at least two treatments given consecutively within the study period. Although a statement has been made in both studies by Chow et al. [3] and Hwang et al. [4] that a make-up qigong course was provided to the wait-list control group after the study period, the qigong course was provided to the control group as a reward rather than an intervention for research purpose and the intervention groups did not receive any other treatments subsequently. No any data after the study periods were analyzed in both studies. Thus, the two studies cannot be regarded as crossover RCTs. His further concern "we are not sure whether the two missing RCTs excluded because of crossover should have retrieved in or not" is also invalid.
Given that only seven RCTs met the inclusion criteria in our review, Dr. Lei raised another concern about meta-analysis of the limited number of included studies. This is indeed a limitation of the evidence base and a challenge that may be applied to a number of systematic reviews with a limited number of included studies. Even so, we do not think Dr. Lei's statement "as limited number of included studies, especially the differences between research methods, it is not suitable for meta-analysis but qualitative analysis" is appropriate. As indicated in this correspondent, the statement was cited from another systematic review on the effectiveness of acupuncture in the treatment of irradiation-induced xerostomia in patients with head and neck cancer [6]. In that review, only three out of 61 articles met the inclusion criteria but were ineligible for meta-analysis. It is apparent that the statement was applied to that review in particular. Generalization of the statement to any other reviews should be cautious. In our review, seven RCTs met the inclusion criteria for each of the PICO elements (participants, interventions, comparisons, and outcomes) as detailed in the Cochrane Handbook [7]. We think our methods are sound and the results are valid.
Due to the limited number of included RCTs and their methodological flaws, we have documented in our review that it is too early to make a conclusive statement about the effectiveness of qigong exercise on stress and anxiety. To facilitate future assessment of the effects of qigong exercise on stress and anxiety, we invite Dr. Lei to provide comments or insights on a solid basis of scientific thinking.
Finally, we would like to express our appreciation for his comments and concerns.
References:
Lei GH: More suitable for a qualitative analysis than a meta-analysis. February 11, 2014. Available at: http://www.biomedcentral.com/1472-6882/14/8/comments.
Wang CW, Chan CH, Ho RT, Chan JS, Ng SM, Chan CL: Managing stress and anxiety through qigong exercise in healthy adults: a systematic review and meta-analysis of randomized controlled trials. BMC Complement Altern Med, 2014, 14(1): 8. doi: 10.1186/1472-6882-14-8.
Chow YWY, Dorcas A, Siu AMH: The effects of qigong on reducing stress and anxiety and enhancing body-mind well-being. Mindfulness 2012,3(1):51-59. doi: 10.1007/s12671-011-0080-3.
Hwang EY, Chung SY, Cho JH, Song MY, Kim S, Kim JW: Effects of a brief Qigong-based stress reduction program (BQSRP) in a distressed Korean population: a randomized trial. BMC Complement Altern Med 2013, 13:113. doi: 10.1186/1472-6882-13-113.
O'Sullivan EM, Higginson IJ: Clinical effectiveness and safety of acupuncture in the treatment of irradiation-induced xerostomia in patients with head and neck cancer: a systematic review. Acupunct Med, (2010, 28(4): 191-199. doi: 10.1136/aim.2010.002733.
Higgins JPT, Green S: Cochrane handbook for systematic reviews of intervention. Chichester, UK: Wiley-Blackwell; 2008
More suitable for a qualitative analysis than a meta-analysis
11 February 2014
Dear Editors,We have read with interest the recent report by Wang and coworkers [1] on managing stress and anxiety through qigong exercise in healthy adults. In a systematic review and meta-analysis of earlier randomized controlled trials, the authors conclude to a significant effect of qigong exercise in pooled stress and anxiety for healthy adults based on data from 199 cases and 199 controls. We really appreciate the work which was done by the authors. At a closer look, however, the positive finding loses its luster.
Firstly, data were extracted by one main researcher and then verified by another researcher. Any discrepancies were resolved by discussion. However, in this process it caused selector bias of the meta-analysis, because data extraction of the second researcher was not blind and independent [2]. Previous studies showed that the odds of error caused by two authors extracting data independently was reduced significantly, compared with data extraction twice successively [3]. Meanwhile, cochrane handbook suggest professionals of different background extract data, such as an epidemiologist and a clinical expert, to ensure avoiding selection bias [4].
Secondly, the authors indicated that crossover RCTs were excluded because their results are subject to carryover bias. But in the analysis of effects of qigong exercise, the included study of Chow et al. [5] and Hwang et al. [6] were both crossover RCTs on anxiety and perceived stress, which also cause carryover bias. Thus, we are not sure whether the two missing RCTs excluded because of crossover should have
been retrieved in or not.
Finally, Seven RCTs met the inclusion criteria. They were conducted in different countries and the characteristics of participants varied in different studies such as age, intervention (frequency), control, duration and relevant outcome measures. As limited number of included studies, especially the differences between research methods, it is not suitable for meta-analysis but qualitative analysis, in order to avoid merging the same kind of research with different results and losing credibility [7].
On the whole, this meta-analysis raises more questions than it answers. To facilitate future assessments of qigong exercise in stress and anxiety, we invite the authors to improve the research that is required to put into perspective the qigong exercise they have recently contributed for stress and anxiety.
Above all, we respect the great contributions of the authors and we are pretty sure the results of the data analysis are accurate with no doubt.
Reference[1] Wang, C. W., Chan, C. H., Ho, R. T., Chan, J. S., Ng, S. M., & Chan, C. L. (2014). Managing stress and anxiety through qigong exercise in healthy adults: a systematic review and meta-analysis of randomized controlled trials. BMC Complement Altern Med, 14(1), 8. doi: 10.1186/1472-6882-14-8.
[2] Felson, D. T. (1992). Bias in meta-analytic research. J Clin Epidemiol, 45(8), 885-892.
[3] Meade, M. O., & Richardson, W. S. (1997). Selecting and appraising studies for a systematic review. Ann Intern Med, 127(7), 531-537.
[4] Higgins JPT, Green S (editors). Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 [updated March 2011]. The Cochrane Collaboration, 2011. Available from www.cochrane-handbook.org.
[5] Chow, YvonneW.Y., Dorcas, Allen, & Siu, AndrewM.H. (2012). The Effects of Qigong on Reducing Stress and Anxiety and Enhancing Body–Mind Well-being. Mindfulness, 3(1), 51-59. doi: 10.1007/s12671-011-0080-3.
[6] Hwang, E. Y., Chung, S. Y., Cho, J. H., Song, M. Y., Kim, S., & Kim, J. W. (2013). Effects of a brief
Qigong-based stress reduction program (BQSRP) in a distressed Korean population: a randomized trial. BMC Complement Altern Med, 13, 113. doi: 10.1186/1472-6882-13-113.
[7] O'Sullivan, E. M., & Higginson, I. J. (2010). Clinical effectiveness and safety of acupuncture in
the treatment of irradiation-induced xerostomia in patients with head and neck cancer: a systematic review. Acupunct Med, 28(4), 191-199. doi: 10.1136/aim.2010.002733.
Competing interests
No competing interests exist.Response to Lei's comments on "Managing stress and anxiety through qigong exercise in healthy adults: a systematic review and meta-analysis of randomized controlled trials"
27 June 2014
Dear Editors:
We have noted the comments [1] given by Dr. Lei on our recent article: "Managing stress and anxiety through qigong exercise in healthy adults: a systematic review and meta-analysis of randomized controlled trials" [2]. In his correspondent, he raised a concern about selection bias in our review and stated that "the included study of Chow et al. [3] and Hwang et al. [4] were both crossover RCTs (randomized controlled trials) on anxiety and perceived stress." We thank Dr. Lei for his opinion, but disagree to his statement. According to Sibbald and Roberts [5], crossover RCT is a longitudinal study in which subjects are randomly allocated to study arms where each arm consists of a sequence of at least two treatments given consecutively within the study period. Although a statement has been made in both studies by Chow et al. [3] and Hwang et al. [4] that a make-up qigong course was provided to the wait-list control group after the study period, the qigong course was provided to the control group as a reward rather than an intervention for research purpose and the intervention groups did not receive any other treatments subsequently. No any data after the study periods were analyzed in both studies. Thus, the two studies cannot be regarded as crossover RCTs. His further concern "we are not sure whether the two missing RCTs excluded because of crossover should have retrieved in or not" is also invalid.
Given that only seven RCTs met the inclusion criteria in our review, Dr. Lei raised another concern about meta-analysis of the limited number of included studies. This is indeed a limitation of the evidence base and a challenge that may be applied to a number of systematic reviews with a limited number of included studies. Even so, we do not think Dr. Lei's statement "as limited number of included studies, especially the differences between research methods, it is not suitable for meta-analysis but qualitative analysis" is appropriate. As indicated in this correspondent, the statement was cited from another systematic review on the effectiveness of acupuncture in the treatment of irradiation-induced xerostomia in patients with head and neck cancer [6]. In that review, only three out of 61 articles met the inclusion criteria but were ineligible for meta-analysis. It is apparent that the statement was applied to that review in particular. Generalization of the statement to any other reviews should be cautious. In our review, seven RCTs met the inclusion criteria for each of the PICO elements (participants, interventions, comparisons, and outcomes) as detailed in the Cochrane Handbook [7]. We think our methods are sound and the results are valid.
Due to the limited number of included RCTs and their methodological flaws, we have documented in our review that it is too early to make a conclusive statement about the effectiveness of qigong exercise on stress and anxiety. To facilitate future assessment of the effects of qigong exercise on stress and anxiety, we invite Dr. Lei to provide comments or insights on a solid basis of scientific thinking.
Finally, we would like to express our appreciation for his comments and concerns.
References:
Competing interests
The author declares no conflict of interest.