Yuan Zhao，Yan WangTianjin University of Traditional Chinese Medicine，Tianjin 300193，China

Original article

Tai Chi as an intervention to reduce falls and improve balance function in the elderly：A meta-analysis of randomized controlled trials

Yuan Zhao*，Yan Wang
Tianjin University of Traditional Chinese Medicine，Tianjin 300193，China

A R T I C L EI N F O

Article history：

Received in revised from

15 February 2015

Accepted 27 October 2015

Available online 21 March 2016

Tai Chi

Balance function

Elderly

Fall

Meta-analysis

Systematic review

Randomized controlled trial

ABSTRACT

Objective：To systematically evaluate the effectiveness of fall prevention and balance function in the elderly.

Methods：Databases，including PubMed，Web of Science，Cochrane Library，Chinese Biomedical Literature Database（CBM），and CNKI were electronically searched，and the relevant references of the included papers were also manually searched.Two reviewers independently screened the articles according to the inclusion and exclusion criteria，extracted the data，and assessed the methodological quality.A metaanalysis was performed using the Cochrane Collaboration's RevMan 5.1 software.

Results：Six randomized controlled trials（RCTs）involving 2796 participants were included.The results of the meta-analysis showed that compared with a physiotherapy intervention，Tai Chi could significantly reduce the incidence rates of falls［relative risk（RR）=0.82，95%confidence interval（CI）（0.73，0.92）］，while there were significant differences in the Timed Up and Go test，F(xiàn)unctional Reach Test and Berger Balance Scale.

Conclusions：Tai Chi is effective in reducing the risk of falls and improving balance in the elderly.

?2016 Shanxi Medical Periodical Press.Production and hosting by Elsevier B.V.This is an open access article under the CC BY-NC-ND license（http：//creativecommons.org/licenses/by-nc-nd/4.0/）.

1.Introduction

Each year，approximately 30%of community-living adults aged 65 and older experience a fall.Falls are the second main cause of accidents with injuries among the elderly，and the medical waste and economic costs associated with non-lethal falls are considerable.In addition，falls among the elderly are considered to be unavoidable and an important research subject in public health.1Some previous studies have indicated that with advancing age，balance decreases more sharply than other physiological functions，2especially among people over the age of 60 years，in whom the ability to balance is significantly impaired and leads to an increased risk of falls；this directly influences the elderly's physical and psychological health.3Results of many studies have shown that physical exercise can improve motor function，the ability to balance，the ability to walk，and the stability and posture of the elderly.4As a traditional Chinese sport，Tai Chi exercises consist of a series of sequential，graceful，and balanced movements that are executed in a slow，meditative，and relaxed manner.5With its mild-to-moderate intensity，Tai Chi improves cardiopulmonary capacity，muscle strength，postural control，spinal flexibility and balance. This meta-analysis focused on reviewing and updating the current evidence on using Tai Chi as an intervention for improving balance and reducing falls in the elderly.

2.Methods

2.1.Types of studies

Studies were included for review only if they were randomized controlled trials（RCTs）.We did not plan to include the results from quasi-RCTs in the analyses，but we may discuss them in the text if limited RCT evidence is available.

2.2.Types of participants

According to the definition of the elderly by the World Health Organization，we included individuals above 60 years of age who live in nursing institutions or local communities and have not practiced Tai Chi in the previous 12 months.Participants were excluded if they had a degenerative neurological condition，such as Parkinson's disease，dementia，or a severely debilitating stroke；severe arthritis；or marked vision impairments or if they were unable to walk across a room independently.

http：//dx.doi.org/10.1016/j.cnre.2015.10.003
2095-7718/? 2016 Shanxi Medical Periodical Press.Production and hosting by Elsevier B.V.This is an open access article under the CC BY-NC-ND license（http：// creativecommons.org/licenses/by-nc-nd/4.0/）.

2.3.Types of interventions

2.3.1.TC group

Tai Chi exercises served as the intervention and were administered for 3 months or more with instructions of an experienced Tai Chi instructor.Participants were not given any particular instructions about performing Tai Chi outside the class.

2.3.2.Control group

Controls were offered regular exercises（RE）or physical treatments（PT），including resistance training，balance training，strength training，or walking training Types of outcome measures.

2.4.Outcomes

2.4.1.Primary outcomes

The primary outcome measure was the number of falls.

2.4.2.Secondary outcome

The secondary outcomes included functional balance and physical performance.Functional balance measures included the Berg Balance Scale（BBS），which evaluates a person's ability to perform 14 different tasks of increasing difficulty，and the Function Reach（FR）measure，which assesses the maximal distance a person can reach forward beyond an arm's length while maintaining a fixed base of support in a standing position.The physical performance tests involved the Timed Up and Go Test（TUG），which is reliable and valid in quantifying functional mobility and was used to assess mobility.

2.5.Search methods for identification of studies

The extensive nature of this topic was reflected in the search of a wide range of resources，both electronic and non-electronic，without language restrictions，covering all relevant databases，including PubMed，Web of Science，Cochrane Library，Chinese Biomedical Literature Database（CBM），and CNKI.For all of the databases，we used the highly sensitive search strategy for randomized controlled trials（RCTs），as suggested in the Cochrane Handbook.All of the relevant articles found were identified on PubMed using the‘related articles’feature，and a further search was carried out for newly published articles.

The PubMed search strategy included the following search terms：‘Aged’（Mesh）OR‘a(chǎn)ged’（Title/Abstract）OR‘elderly’（Title/ Abstract）AND［‘Tai Ji’（Mesh）OR‘Tai Ji’（Title/Abstract）OR‘Tai Chi’（Title/Abstract）］AND［‘clinicaltrial’（Publication Type）OR ‘clinical trials as topic’（MeSH Terms）OR‘clinical trial’（All Fields）OR ‘random’（All Fields）OR‘randomized’（All Fields）OR‘randomization’（All Fields）OR‘randomized’（All Fields）OR‘randomly’（All Fields）OR‘randomness’（All Fields）］.

2.6.Data collection and analysis

2.6.1.Selection of studies

All of the titles and/or abstracts generated by the searches were screened by pairs of authors for potentially relevant studies.The full-length articles of the selected titles and/or abstracts were assessed for eligibility.Disagreement was resolved by consensus or third party adjudication.

2.6.2.Data extraction and management

Two authors independently extracted the data from eligible trials using a customized data extraction tool.We recorded informationaboutthetrialdesign，maincharacteristicsof the participants，intervention modality assessed，and outcomes. Disagreement on the data extracted was resolved by consensus or third party adjudication.We contacted the authors of the studies where there was inadequate reporting of data to enable clarification and，where appropriate，to allow pooling.

2.6.3.Assessment of the risk of bias in the included studies

Two authors independently assessed the risk of bias for each study using the criteria outlined in the Cochrane Handbook for Systematic Reviews of Interventions（Higgins 2011）.We resolved any disagreement by involving a third author in the discussion.We assessed the following domains：（1）Random sequence generation （checking for possible selection bias）；（2）allocation concealment （checking for possible selection bias）；（3）blinding（checking for possible performance bias）；（4）incomplete outcome data（checking for possible attrition bias due to the amount，nature and handlingof incomplete outcome data）；（5）selective reporting（checking for reporting bias），and（6）other bias（checking for bias due to problems not covered by areas 1-5）.

2.7.Measures of treatment effect

For each trial，the risk ratios and 95%confidence intervals were calculated for dichotomous outcomes，and the mean differences （MD）and 95%confidence intervals were calculated for continuous outcomes（reporting mean and standard deviation or standard error of the mean）.The standardized mean differences（SMD）and 95% confidence intervals were calculated when combining the results from studies using different ways of measuring the same concept. The change in scores was reported separately，as these cannot be incorporated into a meta-analysis of standardized mean differences.

2.8.Assessment of heterogeneity

Heterogeneity between comparable studies was tested using visual inspection of the forest plot and a standard chi-square test and was considered statistically significant at p＜0.1；this was done with consideration of the value of the I2statistic，and avalue greater than 50%may indicate substantial heterogeneity.

2.9.Data synthesis

Appropriate statistical analyses were performed using Review Manager in accordance with the Cochrane Handbook for Systematic Reviews of Interventions.6Where available and appropriate，quantitative data for the outcomes listed in the inclusion criteria are presented in the analyses.Where appropriate，the results of the comparable groups of studies were pooled using the fixed-effect model and the 95%confidence intervals were calculated.In the presence of substantial heterogeneity，or an I2statistic greater than 50%，the results of comparable groups of studies were pooled using the random-effects model and the 95%confidence intervals were calculated.

2.10.Sensitivity analysis

We planned to conduct sensitivity analyses to explore the effect of the trial quality as assessed by the concealment of allocation，high attrition rates，or both，with poor quality studies being excluded from the analyses to assess whether this made any difference in the overall result.

Table 1Characteristics of the included studies.

3.Results

3.1.Results of the search

Originally，we retrieved 587 references from our electronic databases searches，which resulted in 339 unique references after resolving overlaps between the sources that were searched.We excluded 326 irrelevant references and selected 133-5，7-16articles for further assessment for their inclusion in the review.Finally，we included six studies with a total of 2796 participants in the metaanalysis（Fig.1）.

3.2.Description of the studies

Characteristics of the included studies are given in Table 1.

3.3.Risk of bias in the included studies

All of the studies stated that the participants were randomly assigned（e.g.，computer-generated table of random numbers，draw of lots，flip of a coin），and some studies stated that they used alternate group assignment as an allocation method.For four studies，the sequence table was held in a sealed envelope in a locked filing cabinet until study completion.Four studies were explicitly single-blinded，using a blinded assessment.All of the studies had low or even no drop-out rates and reported the reasons for dropouts.Three analyses were conducted on an intention-totreat analysis.We did not search for the study protocols to compare to the study publication；however，for all of the studies， the outcomes listed in the methods were reported in the results. For all of the studies，there was a low risk of bias（Figs.2 and 3）.

3.4.Effects of interventions

3.4.1.Falls

Four studies with a total of 1443 participants compared the incidence of falls，including the number of falls，frequency of falls，and fallers.The pooled estimate of the favors TC group［relative risk （RR）=0.82，95%confidence interval（CI）（0.73，0.92）］，without evidence of statistical heterogeneity（I2=19%）.Li et al.found that the number of falls was reduced in the TC group（38 falls）compared to the exercise stretching group（73 falls）during the 6-month postintervention follow-up.Voukelatos et al.reported a 50%relative risk（RR）reduction of two or more falls among those who participated in the TC group compared to the control group（Fig.4）.

3.4.2.Gait

When the primary outcomes were measured immediately postintervention，the TC exercise achieved a statistically significant reduction in the time taken to perform a TUG［SMD=0.23，95%CI （0.09，0.37），780 participants，3 studies］.The fixed effects model was used to pool the data（χ2=0.89，I2=0%）（Fig.5）.

3.4.3.Balance

We also observed effects that were attributable to the TC group，showingsignificantlyimprovedscoresforFunctionalReach ［SMD=0.38，95%CI（0.19，0.57），448 participants，2 studies］compared with the control group，without evidence of statistical heterogeneity（I2=0%）（Fig.6）.

Additionally，the TC exercise achieved a statistically significant improvement in the Berg Balance Score at the end of the intervention［MD=2.45，95%CI（1.47，3.43），345 participants，2 studies］，without evidence of statistical heterogeneity（I2=28%）（Fig.7）.

4.Discussion

This review included 6 RCTs that were from a variety of sources，had similar clinical settings，and showed promising results for the use of Tai Chi in preventing falls in the elderly.According to the integrated and comprehensive evaluation，the results of this review show that taking pertinent treatment measures can reduce the possibility of a fall by 30%-40%.17Wolfson et al.18conducted a collection of analyses and divided sports therapy into 6 main types：walking，balance，andfunctionalexercises；strength training；resistance training；Tai Chi；normal psychical exercises，and endurance training.The results showed that sports therapy had a similar effect across high and low risk groups.However，the analysis on the results of this research showed that Tai Chi was able to improve patients'balance and walking capacity byincreasing muscle strength and improving the ability to keep one's balance and enhance one's flexibility as well as by increasing one's endurance to reduce and prevent the falls；this was statistically significantly better than the regular exercise or physical therapy groups.

The results of this study proved that Tai Chi could improve the ability to stay balanced and increase muscle strength，flexibilityand reacting time，which can help protect the elderly from potential falls.（1）Tai Chi is a form of exercise that can improve the flexibility of the body and mind，as well as adjust breathing，and can increase the cooperation among the hands，eyes and whole body with the mind.Tai Chi can boost the control of the mind on the body and improve the reaction capacity of the elderly.（2）Tai Chi exercises incorporate whole body exercises and some isotonic exercises. Performing Tai Chi exercises can help build muscles on the back and the lower limbs，which can subsequently increase muscle strength. （3）The steps of Tai Chi focus on the exchange between deficiency and excess，and the so-called‘deficiency and excess’（Xu Shi in Chinese）is the proportion of the body weight excreted on the feet；the foot that withstands more body weight is referred to as‘excess，’and the foot with less body weight is referred to as‘deficiency.’‘The exchange between deficiency and excess’actually refers to the change of body weight between each foot.This theory fully emphasizes the capacity to control the distribution of the body weight and adjust the gestures.With the guidance of this theory and cooperation of a series of movements made while standing with a single leg，standing with two legs，or standing with the other leg，the capacity of the elderly to stay balanced and adjust their steps is improved.（4）The Tai Chi pattern includes many movements，which require people to go down on their knees and their waists；this is good for many joints because it increases the movement of the joints and improves flexibility.

As in all systematic reviews，this study is susceptible to bias. Publication bias was likely minimized by the use of a broad search strategy，but some language bias may still exist.Reliability of the risk of bias assessment and data extraction was improved because two researchers performed procedures independently before a consensus was obtained.Bias due to the study design and quality was minimized by including only RCTs and bygiving an overview of the risk of bias assessment.In the present review，there was little possibility to study the influence of heterogeneous sources due to the small number of studies.

This evaluation still has limitations：first，some parameters are of greater importance，such as those of progression；with the loss of these parameters，we were unable to combine and analyze these parameters；second，the timing of the research varied among the studies，which may impact the authenticity of the research；and third，the type of Tai Chi exercises and the forms of physical therapy that wereperformed in the studies varied；in addition，the time and intensity of the exercises were not consistent，which may impact the authenticity of the meta-analysis results.

Conflicts of interest

All contributing authors declare no conflicts of interest.

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29 January 2015

*Corresponding author.
E-mail address：oneinseven1988@163.com（Y.Zhao）.
Peer review under responsibility of Shanxi Medical Periodical Press.