Back to Journals » Clinical Interventions in Aging » Volume 13

Statistical concerns about the study: hypoglycemic and antioxidant effect of Tai chi exercise training in older adults with metabolic syndrome

Authors Aydın T, Oren MM, Bahat G

Received 17 April 2018

Accepted for publication 27 April 2018

Published 11 July 2018 Volume 2018:13 Pages 1233—1235

DOI https://doi.org/10.2147/CIA.S171443

Checked for plagiarism Yes

Editor who approved publication: Dr Richard Walker

Download Article [PDF] 

Tuğba Aydin,1 Meryem Merve Oren,2 Gulistan Bahat3

1Istanbul Physical Medicine and Rehabilitation Training Hospital, Istanbul, Turkey; 2Department of Public Health, Istanbul Medical School, Istanbul, Turkey; 3Department of Internal Medicine, Division of Geriatrics, Istanbul Medical School, Istanbul, Turkey


In their study, Mendoza-Núñez et al studied the effect of Tai chi (TC) exercise on oxidative stress (OxS) in elderly with metabolic syndrome (MetS), with a painstaking study protocol.1 They included a total of 85 older sedentary adults with MetS. The control group did not participate in physical exercise (n=37), and the experimental group was enrolled in a TC exercise training program (n=48). They measured in both groups, in the pre- and post intervention periods, the cardiovascular parameters, OxS markers and inflamma¬tion markers. They concluded that a statistically significant decrease in HbA1c and a decrease in the OxS score were observed in the TC group compared with the control group. They did not observe changes in the cardiovascular parameters.

View the original paper by Mendoza-Núñez and colleagues.
 

Dear editor

In their study, Mendoza-Núñez et al studied the effect of Tai chi (TC) exercise on oxidative stress (OxS) in elderly with metabolic syndrome (MetS), with a painstaking study protocol.1

They included a total of 85 older sedentary adults with MetS. The control group did not participate in physical exercise (n=37), and the experimental group was enrolled in a TC exercise training program (n=48). They measured in both groups, in the pre- and post-intervention periods, the cardiovascular parameters, OxS markers and inflammation markers. They concluded that a statistically significant decrease in HbA1c and a decrease in the OxS score were observed in the TC group compared with the control group. They did not observe changes in the cardiovascular parameters.

However, there seems to be a significant statistical error in the analyses section. They declared that to compare the frequency of OxS pre- and post-intervention, they used the chi-square test. However, importantly, they should have used the McNemar test as these are related samples, not independent samples.2

It has been shown that in analyses of paired data, use of the chi-square test is not acceptable. Instead, in analyses of paired measurements, one should use the McNemar test.3,4 In the three studies referred to by Mendoza-Núñez et al (the references 35–37 in the original paper), the authors did not use the chi-square test but used the McNemar test or some other tests suitable for the paired data.

On the other hand, regarding the effects of TC exercise on cardiovascular parameters, there are many published studies suggesting its favorable effects.5,6 Accordingly, we suggest that the analyses should be repeated with these concerns to have the actual results. This well-designed study which has some significant erroneous statistical analyses approaches.

Disclosure

The authors report no conflicts of interest in this communication.


References

1.

Mendoza-Núñez VM, Arista-Ugalde TL, Rosado-Pérez J, Ruiz-Ramos M, Santiago-Osorio E. Hypoglycemic and antioxidant effect of Tai chi exercise training in older adults with metabolic syndrome. Clin Interv Aging. 2018;13:523–531.

2.

MEDCALC®. Available from: https://www.medcalc.org/manual/mcnemartest2.php. Accessed April 16, 2018.

3.

Hoffman JI. The incorrect use of Chi-square analysis for paired data. Clin Exp Immunol. 1976;24(1):227–229.

4.

Adedokun OA, Burgess WD. Analysis of paired dichotomous data: a gentle introduction to the McNemar test in SPSS. J Multidiscip Eval. 2012;8:125–131.

5.

Shi ZM, Wen HP, Liu FR, Yao CX. The effects of tai chi on the renal and cardiac functions of patients with chronic kidney and cardiovascular diseases. J Phys Ther Sci. 2014;26(11):1733–1736.

6.

Tsai JC, Wang WH, Chan P, et al. The beneficial effects of Tai Chi Chuan on blood pressure and lipid profile and anxiety status in a randomized controlled trial. J Altern Complement Med. 2003;9(5):747–754.

Authors’ reply

Víctor Manuel Mendoza-Núñez1 Taide Laurita Arista-Ugalde1 Juana Rosado-Pérez1 Mirna Ruiz-Ramos1 Edelmiro Santiago-Osorio2

1Research Unit on Gerontology, Facultad de Estudios Superiores Zaragoza, National Autonomous University of Mexico, Mexico City, Mexico; 2Hematopoiesis and Leukemia Laboratory, Research Unit on Cell Differentiation and Cancer, Facultad de Estudios Superiores Zaragoza, National Autonomous University of Mexico, Mexico City, Mexico

Correspondence: Víctor Manuel Mendoza-Núñez, Research Unit on Gerontology, Facultad de Estudios Superiores Zaragoza, National Autonomous University of Mexico, Guelatao No 66, Colonia Ejército de Oriente, 09230 Mexico City, DF, Mexico, Tel +52 55 5623 0721, Fax +52 55 5773 6330, Email [email protected]

Dear editor

We greatly appreciate the interest of Aydin et al in reading and reviewing our recently published research “Hypoglycemic and antioxidant effect of Tai chi exercise training in older adults with metabolic syndrome”.1 Aydin et al point out an error in the analyses section related to comparison of the frequency of oxidative stress (OxS) pre- and post-intervention, as we have used the chi-square test. Aydin et al also point out that we should have used the McNemar test as these are related samples, not independent samples. We agree with this comment, so we did the statistical analysis again to compare the frequency of OxS pre- and post-intervention using the McNemar test and found that the statistically significant difference between the Tai chi and control groups was maintained (Table 1).

Table 1 Frequency of oxidative stress pre- and post-intervention
Notes: McNemar’s test was applied. *p=0.5; **p=0.004.
Abbreviation: OxS, oxidative stress.

Regarding the second comment about the effects of TC exercises on cardiovascular parameters, we did the statistical analysis again and the results were verified without changes.

Disclosure

The authors report no conflicts of interest in this communication.


Reference

1.

Mendoza-Núñez VM, Arista-Ugalde TL, Rosado-Pérez J, Ruiz-Ramos M, Santiago-Osorio E. Hypoglycemic and antioxidant effect of Tai chi exercise training in older adults with metabolic syndrome. Clin Interv Aging. 2018;13:523–531.

Dove Medical Press encourages responsible, free and frank academic debate. The content of the Clinical Interventions in Aging ‘letters to the editor’ section does not necessarily represent the views of Dove Medical Press, its officers, agents, employees, related entities or the Clinical Interventions in Aging editors. While all reasonable steps have been taken to confirm the content of each letter, Dove Medical Press accepts no liability in respect of the content of any letter, nor is it responsible for the content and accuracy of any letter to the editor.

Creative Commons License This work is published and licensed by Dove Medical Press Limited. The full terms of this license are available at https://www.dovepress.com/terms.php and incorporate the Creative Commons Attribution - Non Commercial (unported, v3.0) License. By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. For permission for commercial use of this work, please see paragraphs 4.2 and 5 of our Terms.

Download Article [PDF]