Osteoporos Int (2008) 19:139–146 DOI 10.1007/s00198-007-0486-x
REVIEW
Tai chi for osteoporosis: a systematic review M. S. Lee & M. H. Pittler & B.-C. Shin & E. Ernst
Received: 19 June 2007 / Accepted: 17 September 2007 / Published online: 23 October 2007 # International Osteoporosis Foundation and National Osteoporosis Foundation 2007
Abstract Introduction Tai chi may have beneficial effects with respect to balance, falls and non-vertebral fractures. The purpose of this systematic review was to evaluate evidence from controlled clinical trials testing the effectiveness of tai chi for osteoporosis. Methods Systematic searches were conducted on 20 electronic databases. The outcome measures considered for inclusion were changes in bone parameters. Results Five randomized clinical trials (RCTs) and two controlled clinical trials (CCT) met all inclusion criteria. In postmenopausal women, one RCT found tai chi to be superior for loss of bone mineral density (BMD) compared with sedentary lifestyle, while two other RCTs found no differences between tai chi and exercises or calcium supplementation for BMD. The meta-analysis showed no significant effect of tai chi on BMD change at the spine compared with no treatment in postmenopausal women. One RCT failed to show favorable effects of tai chi compared with resistance training (RT) for total hip BMD in elderly women. A further RCT compared tai chi with RT on bone metabolism and reported favorable effects compared with RT in the elderly.
Financial support: None M. S. Lee (*) : M. H. Pittler : E. Ernst Complementary Medicine, Peninsula Medical School, Universities of Exeter & Plymouth, 25 Victoria Park Road, Exeter EX2 4NT, UK e-mail:
[email protected] e-mail:
[email protected] B.-C. Shin Department of Oriental Rehabilitation, College of Oriental Medicine, Wonkwang University, Iksan, South Korea
Conclusion The evidence for tai chi in the prevention or treatment of osteoporosis is not convincing. More rigorous research seems warranted. Keywords Balance . Bone metabolism . Bone mineral density . Falls . Osteoporosis . Tai chi
Introduction Osteoporosis is the most common metabolic bone disorder [1, 2]. It is estimated that about 44 million individuals in the US over the age of 50 years have osteoporosis or low bone mass [1, 3]. Thus it is a major contributor to individual suffering and represents a significant social economic burden. The annual direct care expenditures for osteoporosis-related fractures range from US $12 to 18 billion in 2002 [3]. Indirect costs are likely to add one billion dollars to this figure [3]. Treatment of osteoporosis involves use of either antiresorption agents or bone formation agents. Because of the potential for adverse reactions to pharmacologic therapy and its high costs, complementary therapies, which are often considered safer, are popular. Possible options include exercise, herbal medicine, massage, relaxation techniques and tai chi. Regular exercise is strongly recommended, and there is some evidence suggesting its effectiveness [4–6]. Tai chi is an intervention that combines deep breathing and relaxation with slow and gentle exercise [7]. Practicing tai chi might bring about a change in lifestyle, which is considered as one of the causal factors in osteoporosis [8]. It has also been reported that tai chi has beneficial effects on reducing high blood pressure, balance, muscle strength and fall prevention [9–12]. Results of cross-sectional studies suggest that tai chi is beneficial for preventing osteoporosis [13–16]. Tai chi is also a safe intervention with a low risk for serious side
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effects [11, 12]. Given its safety and potential effectiveness, it seems pertinent to evaluate the trial data on the effectiveness of tai chi for treating or preventing osteoporosis. The aims of this article are to systematically overview and critically assess the evidence from controlled clinical trials of tai chi for treating or preventing osteoporosis.
Methods Data sources Electronic databases were searched from their respective inceptions through March 2007 using the following databases: MEDLINE, AMED, British Nursing Index, CINAHL, EMBASE, PsycInfo, the ClinicalTrials.gov of National Institute of Health and National Research Register, The Cochrane Library 2007, Issue 1, Korean medical databases (Korean Studies Information, DBPIA, Korea Institute of Science and Technology Information, Research Information Center for Health Database, Korean Medline, and Korea National Assembly Library), Qigong and Energy Medicine Database (Qigong Institute, Melon Park, version 7.3) and Chinese databases (China Academic Journal, Century Journal Project, China Doctor/Master Dissertation Full text DB, China Proceedings Conference Full text DB). The search terms used were (taichi OR tai adj chi OR taiji) AND (osteoporosis OR bone density OR bone loss). In addition, our own files and relevant journals (FACT - Focus on Alternative and Complementary Therapies, from 1996 to 2007) were manually searched. Several tai chi associations (n=10) and experts (n=4) were contacted and asked to contribute any unpublished trials. In addition, the references of all located articles and the proceedings of the first International Conference of Tai Chi for Health (December 2006, Seoul, South Korea) were hand-searched for further relevant articles. Study selection All prospective controlled clinical trials of tai chi for preventing or treating osteoporosis were included. There were no restrictions on population characteristics. The outcome measures considered for inclusion were percent changes in bone parameters (which may be represented as bone mineral content or density, bone mass, bone metabolism) in intervention groups compared with control. No language restrictions were imposed. Dissertations and abstracts were included. Hardcopies of all articles were obtained and read in full.
Osteoporos Int (2008) 19:139–146
treatments for intervention and control groups (Table 1). The Jadad score [17] was calculated by assessing three criteria: description of randomization, blinding and withdrawals; the score ranges from a minimum of 0 to a maximum of 5 points. Taking into account that patients and therapists are virtually impossible to blind to tai chi, we gave one point if the outcome assessor was blinded. Allocation concealment was assessed using the Cochrane collaboration’s classification. Selection, data extraction and quality assessment were performed independently by two reviewers (MSL, BCS). Discrepancies were resolved by discussion between two reviewers (MSL, MHP) and if needed, by seeking the opinion of the third reviewer (EE). Data synthesis The mean change of bone mineral density (BMD) compared with baseline was used to assess the differences between the intervention groups and the control groups. Weighted mean differences (WMD) and 95% confidence interval (CI) were calculated using the Cochrane Collaboration’s software (Review Manager (RevMan) Version 5.0 for Windows. Copenhagen: The Nordic Cochrane Centre). The variance of the change was imputed using a correlation factor of 0.4 suggested by the Cochrane Collaboration. The chi-square test and the Higgins I2 test were used to assess heterogeneity. Homogeneous datasets were statistically pooled using a random effects model.
Results The searches identified 31 potentially relevant studies, of which 24 studies were excluded (Fig. 1). Seven trials, 5 RCTs [18–22] and 2 CCTs [23, 24] (Table 1) met the inclusion criteria. One RCT [25], which included men with osteoporosis, was excluded because the main outcome measures were not related to bone parameters but to balance. Three RCTs [18, 21, 22] and one CCT [24] tested tai chi for postmenopausal women, and two RCTs [19, 20] and one CCT [23] tested tai chi in the elderly. The number of tai chi sessions ranged from 32 to about 280. The number of supervised interventions ranged from 2 to 7 sessions weekly. Duration ranged from 40 min to 60 min per session. Outcome measures Postmenopausal women
Data extraction and quality assessment Data were extracted systematically in a predefined, standardised manner according to design, number of subjects, and
Three RCTs [18, 21, 22], enrolling 256 participants, and 1 CCT [24] including 40 subjects, tested tai chi for postmenopausal women. The methodological quality of
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these trials was low. None of these trials reported details on randomization, blinding and allocation concealment. Sufficient details of drop-outs and withdrawals was descried in one trial [18]. Tai chi was compared with sedentary lifestyle, exercise or calcium supplements in three studies for changes of BMD [18, 21, 22]. One RCT [18] found tai chi to be superior for loss of BMD in the distal tibia compared with sedentary lifestyle, while two other RCTs [21, 22] found no difference between tai chi and exercise or calcium supplements for BMD. The meta-analysis of tai chi on BMD change at the spine compared with no treatment in postmenopausal women showed no significant effect (n= 183, WMD, g/cm2 0.02, 95% CI −0.02 to 0.06, P=0.31, heterogeneity: χ2 =0.52, P=0.91, I2 =0%) (Fig. 2). One CCT [24] showed the effects of tai chi on serum osteocalcin, pyridinoline and deoxypyridinoline in 40 postmenopausal women, reporting significant changes compared with baseline values for all three parameters. The elderly Two RCTs [19, 20], enrolling 208 participants, and 1 CCT [23], including 57 subjects assessed elderly subjects. The methodological quality of these trials was moderate. Two trials [19, 20] described the methods of randomization and one [20] reported assessor blinding as well as allocation concealment. Sufficient details of drop-outs and withdrawals were described in the two RCTs [19, 20]. One RCT [20] assessed the effectiveness of tai chi on BMD compared with resistance training (RT) and no treatment, and failed to show favorable effects of tai chi compared with RT for total hip BMD in women, while there were no significant differences in elderly men. There were no intergroup differences for total BMD of the spine in both genders. Another RCT [19] compared tai chi with RT on bone metabolism. After 6 weeks, both tai chi and RT stimulated bone specific alkaline phosphatase (BAP) relative to baseline but tai chi stimulated BAP significantly more than RT. Tai chi increased parathyroid hormone (PTH) compared with RT at 12 weeks. Another CCT [23] showed that tai chi improved total BMD (site was not reported, P
