Effects of Tai Chi on exercise capacity and health-related quality of life in patients with chronic obstructive pulmonary disease: a systematic review and meta-analysis

Figures & data

Figure 1 Flow diagram of article selection process.

Table 1 Characteristics of included studies

Study	Study design	Sample size	Mean (SD) age, years	Percent men	Disease severity	Intervention protocol	Outcomes
Chan et al^Citation27	RCT (single-blind)	TC: 70 PE: 69 NE: 67	TC: 71.7 (8.2) PE: 73.6 (7.5) NE: 73.6 (7.4)	91.0%	16% mild stage, 42% moderate stage, 43% severe stage; mean FEV1 0.9±0.4	TC: 13-form TC, 12 weeks, twice per week, 60 minutes per time PE: PLB, DB, self-paced walking, 12 weeks, 1 hour per day NE: routine activities	HRQoL (SGRQ)
Yeh et al^Citation23	RCT (single-blind)	TC: 5 NE: 5	TC: 65 (6) NE: 66 (6)	60.0%	Total mean FEV1% predicted 50%±7%	TC: Yang-style TC, 12 weeks, twice per week, 60 minutes per time NE: usual care	6MWD, HRQoL (CRQ)
Chan et al^Citation20	RCT (single-blind)	TC: 70 PE: 69 NE: 67	TC: 71.7 (8.2) PE: 73.6 (7.5) NE: 73.6 (7.4)	91.0%	16% mild stage, 42% moderate stage, 43% severe stage; mean FEV1 0.9±0.4	TC: 13-form TC, 12 weeks, twice per week, 60 minutes per time PE: PLB, DB, self-paced walking, 12 weeks, 1 hour per day NE: routine activities	6MWD
Zhang et al^Citation22	RCT	TC: 30 PE: 30 NE: 30	TC: 63.1 (7.3) PE: 62.3 (6.9) NE: 62.0 (7.3)	56.7%	Total mean FEV1% predicted 52.0%±8.2%	TC: 24-form TC, PLB, RMT, 24 weeks, once per day, 30–60 minutes per time PE: PLB, RMT, 24 weeks, 3–4 times per day, 15–30 minutes per time NE: usual medical care	6MWD, HRQoL (SGRQ),
Li et al^Citation32	RCT	TC: 35 PE: 35	TC: 72.0 (2.5) PE: 73.2 (3.0)	78.6%	60% moderate stage, 40% severe stage	TC: 24-form TC, BE, 24 weeks, once per day, 60 minutes per time PE: BE	HRQoL (SGRQ)
Gu et al^Citation33	RCT	TC: 33 NE: 30	TC: 67 (8) NE: 69 (9)	85.7%	Total mean FEV1% predicted 50.0%±19.4%	TC: 24-form TC, 12 weeks, 3 times per week, 60 minutes per time NE: health-related knowledge education	6MWD
Leung et al^Citation18	RCT (single-blind)	TC: 22 NE: 20	TC: 73 (8) NE: 75 (8)	64.3%	Total mean FEV1% predicted 59%±15%	TC: Sun-style TC, 12 weeks, twice per week, 60 minutes per time NE: usual medical care	HRQoL (CRQ)
Niu et al^Citation28	RCT (single-blind)	TC: 19 NE: 20	TC: 61.3 (8.0) NE: 59.7 (2.8)	92.5%	Total mean FEV1% predicted 42.8%±5.3%	TC: TC, 24 weeks, once per day, 50 minutes per time NE: usual medical care	6MWD
Ng et al^Citation29	RCT (single-blind)	TC: 94 PE: 98	TC: 74.1 (6.8) PE: 74.2 (6.5)	91.2%	20.5% mild stage, 40.6% moderate stage, 30.2% severe stage; total mean FEV1% predicted 59.8%±23.2%	TC: Sun-style TC, PRP, 24 weeks, 5–7 times per week, 80 minutes per time PE: PRP (aerobics, BE, strength training), 24 weeks, 5–7 times per week, 80 minutes per time	6MWD HRQoL (SGRQ)
Du et al^Citation30	RCT	TC: 36 PE: 38 NE: 38	TC: 65.2 (8.3) PE: 62.4 (6.2) NE: 64.5 (6.5)	62.5%	29.5% mild stage, 70.5% moderate stage; total mean FEV1% predicted 73.54%±6.73%	TC: 24-form Yang-style TC, 12 weeks, once per day, 60 minutes per time PE: PLB, DB, walking exercise, 12 weeks, 1 hour PLB and DB, 30 minutes walking per day NE: routine activities	6MWD
Du et al^Citation31	RCT	TC: 36 PE: 38 NE: 38	TC: 65.2 (8.3) PE: 62.4 (6.2) NE: 64.5 (6.5)	62.5%	29.5% mild stage, 70.5% moderate stage; total mean FEV1% predicted 73.54%±6.73%	TC: 24-form Yang-style TC, 12 weeks, once per day, 60 minutes per time PE: PLB, DB, walking exercise, 12 weeks, 1 hour PLB and DB, 30 minutes walking per day NE: routine activities	HRQoL (SGRQ)

Abbreviations: RCT, randomized controlled trial; TC, Tai Chi group; NE, nonexercise group; PE, physical exercise group; SD, standard deviation; FEV₁, forced expiratory volume in one second; PRP, pulmonary rehabilitation program; PLB, pursed-lip breathing; RMT, respiratory muscle training; BE, breathing exercise; DB, diaphragmatic breathing; 6MWD, six-minute walking distance; HRQoL, health-related quality of life; SGRQ, St George’s Respiratory Questionnaire; CRQ, Chronic Respiratory Disease Questionnaire.

Table 2 Assessment of included studies for methodology

Study	Random allocation	Concealed location	Baseline similar	Blinding (subject)	Blinding (therapist)	Blinding (assessor)	Measures for >85%	ITT	Group comparison	Point measures	Quality score
Yeh et al^Citation23	Yes	No	Yes	No	No	Yes	Yes	Yes	Yes	Yes	7
Chan et al^Citation20,Citation27	Yes	No	Yes	No	No	Yes	Yes	Yes	Yes	Yes	7
Zhang et al^Citation22	Yes	No	Yes	No	No	No	No	No	Yes	Yes	4
Li et al^Citation32	Yes	No	Yes	No	No	No	No	No	Yes	Yes	4
Gu et al^Citation33	Yes	No	Yes	No	No	No	No	No	Yes	Yes	4
Leung et al^Citation18	Yes	Yes	Yes	No	No	Yes	Yes	Yes	Yes	Yes	8
Niu et al^Citation28	Yes	No	Yes	No	No	Yes	Yes	No	Yes	Yes	6
Ng et al^Citation29	Yes	No	Yes	No	No	Yes	Yes	Yes	Yes	Yes	7
Du et al^Citation30,Citation31	Yes	No	Yes	No	No	No	No	No	Yes	Yes	4

Abbreviation: ITT, intention-to-treat analysis.

Table 3 Assessment of included studies for risk of bias

Study	Adequate sequence generation	Allocation concealment	Blinding of participants and personnel	Blinding of outcome assessment	Incomplete outcome data	Selective reporting	Other bias
Yeh et al^Citation23	Low	Unclear	Unclear	Low	Low	Low	Unclear
Chan et al^Citation20,Citation27	Low	Unclear	Unclear	Low	Low	Low	Unclear
Zhang et al^Citation22	Unclear	Unclear	Unclear	Unclear	Low	Low	Unclear
Li et al^Citation32	Low	Unclear	Unclear	Unclear	Low	Low	Unclear
Gu et al^Citation33	High	Unclear	Unclear	Unclear	Low	Low	Unclear
Leung et al^Citation18	Low	Low	Unclear	Low	Low	Low	Unclear
Niu et al^Citation28	Low	Unclear	Unclear	Low	Low	Low	Unclear
Ng et al^Citation29	Low	Unclear	Unclear	Low	Low	Low	Unclear
Du et al^Citation30,Citation31	Low	Unclear	Unclear	Unclear	Low	Low	Unclear

Figure 2 Meta-analysis of the effect of Tai Chi on 6MWD in COPD patients.

Notes: (A) Tai Chi group versus nonexercise group; (B) Tai Chi group versus physical exercise group.
Abbreviations: COPD, chronic obstructive pulmonary disease; TC, Tai Chi group; NE, nonexercise group; PE, physical exercise group; CI, confidence interval; 6MWD, six-minute walking distance.

Table 4 Sensitivity analyses of included studies for 6MWD

	Studies	N (n)	MD (95% CI)	P-value	I^2 (%)	Pheterogeneity
TC versus NE	All included studies	6 (383)	35.99 (15.63, 56.35)	0.0005	86%	<0.00001
	High quality studies (PEDro ≥6/10)	3 (186)	44.08 (28.80, 59.37)	<0.00001	29%	0.25
	Low quality studies (PEDro ≤5/10)	3 (197)	27.72 (2.64, 52.81)	0.03	70%	0.04
TC versus PE	All included studies	4 (411)	13.87 (−1.49, 29.23)	0.08	63%	0.04
	High quality studies (PEDro ≥6/10)	2 (331)	18.77 (3.44, 34.11)	0.02	0%	0.37
	Low quality studies (PEDro ≤5/10)	2 (134)	10.72 (−13.79, 35.24)	0.39	72%	0.06

Abbreviations: TC, Tai Chi group; NE, non exercise group; PE, physical exercise group; PEDro, Physiotherapy Evidence Database; N, number of studies; n, number of patients; MD, mean difference; CI, confidence interval; 6MWD, six-minute walking distance.

Figure 3 Meta-analysis of the effect of Tai Chi on SGRQ total score in COPD patients.

Notes: (A) Tai Chi group versus nonexercise group. (B) Tai Chi group versus physical exercise group.

Abbreviations: COPD, chronic obstructive pulmonary disease; TC, Tai Chi group; NE, nonexercise group; PE, physical exercise group; CI, confidence interval; SGRQ, St George’s Respiratory Questionnaire.

Figure 4 Meta-analysis of the effect of Tai Chi on CRQ total score in patients with COPD.

Note: Tai Chi group versus no exercise group.
Abbreviations: COPD, chronic obstructive pulmonary disease; TC, Tai Chi group; NE, non exercise group; CI, confidence interval; CRQ, Chronic Respiratory Disease Questionnaire.

Table 5 Meta-analyses of domain scores of SGRQ

	Outcome	N (n)	MD (95% CI)	P-value	I^2 (%)	Pheterogeneity
TC versus NE	Symptoms	3 (271)	−9.91 (−14.16, −5.66)	<0.00001	0%	0.76
	Activity	3 (271)	−11.15 (−23.23, 0.92)	0.07	82%	0.004
	Influence	3 (271)	−10.11 (−19.60, −0.62)	0.04	84%	0.02
TC versus PE	Symptoms	5 (525)	−1.45 (−4.12, 1.22)	0.29	0%	0.96
	Activity	5 (525)	−5.06 (−8.75, −1.56)	0.005	27%	0.24
	Influence	5 (525)	−2.11 (−4.46, 0.23)	0.08	0%	0.42

Abbreviations: TC, Tai Chi group; NE, nonexercise group; PE, physical exercise group; N, number of studies; n, number of patients; MD, mean difference; CI, confidence interval; SGRQ, St George’s Respiratory Questionnaire.

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