Is yoga effective in reducing negative emotions among patients with breast cancer?
Date of publication of the systematic review: September 2016
Design
Systematic review of 21 randomized controlled trials (RCTs).
Participants
1762 adults with breast cancer aged 18 years old or above. The reviewers did not report mean age and gender proportion of the participants.
Intervention
Yoga practices including Hatha yoga or restorative yoga were used as intervention. Duration of yoga practices ranged from 2 to 24 weeks. The reviewers did not report frequency of the intervention.
Comparator
Comparison: Yoga versus usual care, delayed treatment, health education or supportive therapy (counseling and coping preparation).
Major Outcomes
Outcome 1: Immediate post-treatment effects on anxiety as measured by Hospital Anxiety and Depression Scale (HADS), State Trait Anxiety Inventory (STAI), Distressed Mood Index (DMI) or Self-rating Anxiety Scale (SAS);
Outcome 2: Immediate post-treatment effects on depression as measured by HADS, Centre of Epidemiologic Studies Depression (CESD), Beck’s Depression Inventory (BDI) or Self-rating Depression Scale (SDS);
Outcome 3: Post-treatment psychological distress as measured by Positive and negative affect schedule (PANAS), Rotterdam Symptom Checklist (RSCL) or DMI;
Outcome 4: Post-treatment perceived stress as measured by Perceived Stress Scale (PSS);
Outcome 5: Post-treatment emotional well-being as measured by Functional Assessment of Cancer Therapy (FACT) , Medical Outcomes Study 36-item short-form survey and European Organization for Research and Treatment of Cancer Quality of Life Questionnaire C30 (EORTC-QLQ-C30).
Settings
These studies were performed in outpatient settings.
Comparison    Yoga versus usual care, delayed treatment, health education or supportive therapy
Main Results
Compared to usual care, delayed treatment, health education or supportive therapy, yoga showed significant immediate effects on reducing anxiety (pooled mean difference (pooled MD): -0.42, 95% CI: -0.57 to -0.26), depression (pooled MD: -0.77, 95% CI: -0.89 to -0.65), distress (pooled MD: -0.60, 95% CI: -0.78 to -0.42), perceived stress (pooled MD: -0.82, 95%CI: -1.12 to -0.52) and have improved emotional well-being (pooled MD: 0.34, 95% CI: 0.16 to 0.51).
Comparison: Yoga versus usual care, delayed treatment, health education or supportive therapy among breast cancer patients
Outcomes No. of studies (Total no. of participants) Mean score/ No. of participants Heterogeneity test (I2) Pooled MD (95% CI) Overall quality of evidence*
Intervention Comparator
1 9 (696) Not reported/358 Not reported/338 36% -0.42 (-0.57 to -0.26) Moderate
2 13 (1150) Not reported/565 Not reported/585 40% -0.77 (-0.89 to -0.65) Moderate
3 6 (508) Not reported/267 Not reported/241 12% -0.60 (-0.78 to -0.42) Moderate
4 3 (187) Not reported/95 Not reported/92 36% -0.82 (-1.12 to -0.52) Moderate
5 8 (529) Not reported/285 Not reported/244 0% 0.34 (0.16 to 0.51) Moderate
Keys: MD = mean difference, CI = confidence interval.
Comparison    Yoga versus usual care, delayed treatment, health education or supportive therapy
Main Results
Compared to usual care, delayed treatment, health education or supportive therapy, yoga showed significant immediate effects on reducing anxiety (pooled mean difference (pooled MD): -0.42, 95% CI: -0.57 to -0.26), depression (pooled MD: -0.77, 95% CI: -0.89 to -0.65), distress (pooled MD: -0.60, 95% CI: -0.78 to -0.42), perceived stress (pooled MD: -0.82, 95%CI: -1.12 to -0.52) and have improved emotional well-being (pooled MD: 0.34, 95% CI: 0.16 to 0.51).
Comparison: Yoga versus usual care, delayed treatment, health education or supportive therapy among breast cancer patients
Outcomes 1 2 3 4 5
No. of studies (Total no. of participants) 9 (696) 13 (1150) 6 (508) 3 (187) 8 (529)
Mean score/ No. of participants Intervention Not reported/358 Not reported/565 Not reported/267 Not reported/95 Not reported/285
Comparator Not reported/338 Not reported/585 Not reported/241 Not reported/92 Not reported/244
Pooled MD (95% CI) -0.42 (-0.57 to -0.26) -0.77 (-0.89 to -0.65) -0.60 (-0.78 to -0.42) -0.82 (-1.12 to -0.52) 0.34 (0.16 to 0.51)
Overall quality of evidence* Moderate Moderate Moderate Moderate Moderate
Keys: MD = mean difference, CI = confidence interval.
Conclusion
Benefits
Compared to usual care, delayed treatment, health education or supportive therapy, yoga showed significant immediate effects on reducing anxiety, depression, distress, perceived stress and, is considered effective in improving emotional well-being among breast cancer patients. For all outcomes, the overall quality of evidence is moderate. Further research is fairly likely to have an important impact on our confidence in this estimate of effect.
Harms
No adverse events related to yoga were reported in the included trials.
Link to Original Article
http://www.sciencedirect.com/science/article/pii/S2352013216300011
The synopsis is based on the following article:
Zuo XL, Li Q, Gao F, Yang L, Meng FJ. Effects of yoga on negative emotions in patients with breast cancer: A meta-analysis of randomized controlled trials. International Journal of Nursing Sciences. 2016 Sep 30;3(3):299-306.


* Interpretation of quality assessment results:
• Very low: Further research is most likely to have an important impact on our confidence in this estimate of effect.
• Low: Further research is likely to have an important impact on our confidence in this estimate of effect.
• Moderate: Further research is fairly likely to have an important impact on our confidence in this estimate of effect.
• High: Further research is unlikely to have an important impact on our confidence in this estimate of effect.
• Very high: Further research is most unlikely to have an important impact on our confidence in this estimate of effect.

Details of assessment method can be found at Chung VC, Wu XY, Ziea ET, Ng BF, Wong SY, Wu JC. Assessing internal validity of clinical evidence on effectiveness of CHinese and integrative medicine: Proposed framework for a CHinese and Integrative Medicine Evidence RAting System (CHIMERAS). European Journal of Integrative Medicine. 2015 Aug 31;7(4):332-41.