Characteristics of randomized controlled trials of yoga: A bibliometric analysis

© 2014 Cramer et al.; licensee BioMed Central Ltd. Background: A growing number of randomized controlled trials (RCTs) have investigated the therapeutic value of yoga interventions. This bibliometric analysis aimed to provide a comprehensive review of the characteristics of the totality of available randomized yoga trials. Methods: All RCTs of yoga were eligible. Medline/PubMed, Scopus, the Cochrane Library, IndMED, and the tables of content of yoga specialty journals not listed in medical databases were screened through February 2014. Bibliometric data, data on participants, and intervention were extracted and analyzed descriptively. Results: Published between 1975 and 2014, a total of 366 papers were included, reporting 312 RCTs from 23 different countries with 22,548 participants. The median study sample size was 59 (range 8-410, interquartile range = 31, 93). Two hundred sixty-four RCTs (84.6%) were conducted with adults, 105 (33.7%) with older adults and 31 (9.9%) with children. Eighty-four RCTs (26.9%) were conducted with healthy participants. Other trials enrolled patients with one of 63 varied medical conditions; the most common being breast cancer (17 RCTs, 5.4%), depression (14 RCTs, 4.5%), asthma (14 RCTs, 4.5%) and type 2 diabetes mellitus (13 RCTs, 4.2%). Whilst 119 RCTs (38.1%) did not define the style of yoga used, 35 RCTs (11.2%) used Hatha yoga and 30 RCTs (9.6%) yoga breathing. The remaining 128 RCTs (41.0%) used 46 varied yoga styles, with a median intervention length of 9 weeks (range 1 day to 1 year; interquartile range = 5, 12). Two hundred and forty-four RCTs (78.2%) used yoga postures, 232 RCTs (74.4%) used breath control, 153 RCTs (49.0%) used meditation and 32 RCTs (10.3%) used philosophy lectures. One hundred and seventy-four RCTs (55.6%) compared yoga with no specific treatment; 21 varied control interventions were used in the remaining RCTs. Conclusions: This bibliometric analysis presents the most complete up-to-date overview on published randomized yoga trials. While the available research evidence is sparse for most conditions, there was a marked increase in published RCTs in recent years

Mindfulness-based stress reduction for breast cancer- A systematic review and meta-analysis

Objective The aim of this systematic review and meta-analysis was to assess the effectiveness of mindfulness-based stress reduction (MBSR) and mindfulness-based cognitive therapy (MBCT) in patients with breast cancer. Methods The medline, Cochrane Library, embase, cambase, and PsycInfo databases were screened through November 2011. The search strategy combined keywords for MBSR and MBCT with keywords for breast cancer. Randomized controlled trials (RCTs) comparing MBSR or MBCT with control conditions in patients with breast cancer were included. Two authors independently used the Cochrane risk of bias tool to assess risk of bias in the selected studies. Study characteristics and outcomes were extracted by two authors independently. Primary outcome measures were health-related quality of life and psychological health. If at least two studies assessing an outcome were available, standardized mean differences (SMDS) and 95% confidence intervals (CIs) were calculated for that outcome. As a measure of heterogeneity, I 2 was calculated. Results Three RCTs with a total of 327 subjects were included. One RCT compared MBSR with usual care, one RCT compared MBSR with free-choice stress management, and a three-arm RCT compared MBSR with usual care and with nutrition education. Compared with usual care, MBSR was superior in decreasing depression (SMD: -0.37; 95% CI: -0.65 to -0.08; p = 0.01; I 2 = 0%) and anxiety (SMD: -0.51; 95% CI: -0.80 to -0.21; p = 0.0009; I 2 = 0%), but not in increasing spirituality (SMD: 0.27; 95% CI: -0.37 to 0.91; p = 0.41; I 2 = 79%). Conclusions There is some evidence for the effectiveness of MBSR in improving psychological health in breast cancer patients, but more RCTs are needed to underpin those results. © 2012 Multimed Inc

A Systematic Review and Meta-Analysis Estimating the Expected Dropout Rates in Randomized Controlled Trials on Yoga Interventions

© 2016 Holger Cramer et al. A reasonable estimation of expected dropout rates is vital for adequate sample size calculations in randomized controlled trials (RCTs). Underestimating expected dropouts rates increases the risk of false negative results while overestimating rates results in overly large sample sizes, raising both ethical and economic issues. To estimate expected dropout rates in RCTs on yoga interventions, MEDLINE/PubMed, Scopus, IndMED, and the Cochrane Library were searched through February 2014; a total of 168 RCTs were meta-analyzed. Overall dropout rate was 11.42% (95% confidence interval [CI] = 10.11%, 12.73%) in the yoga groups; rates were comparable in usual care and psychological control groups and were slightly higher in exercise control groups (rate = 14.53%; 95% CI = 11.56%, 17.50%; odds ratio = 0.82; 95% CI = 0.68, 0.98; p = 0.03). For RCTs with durations above 12 weeks, dropout rates in yoga groups increased to 15.23% (95% CI = 11.79%, 18.68%). The upper border of 95% CIs for dropout rates commonly was below 20% regardless of study origin, health condition, gender, age groups, and intervention characteristics; however, it exceeded 40% for studies on HIV patients or heterogeneous age groups. In conclusion, dropout rates can be expected to be less than 15 to 20% for most RCTs on yoga interventions. Yet dropout rates beyond 40% are possible depending on the participants' sociodemographic and health condition

Effect of yoga on chronic non-specific neck pain: An unconditional growth model

© 2017 Elsevier Ltd Objective: Chronic neck pain is a common problem that affects approximately half of the population. Conventional treatments such as medication and exercise have shown limited analgesic effects. This analysis is based on an original study that was conducted to investigate the physical and behavioral effects of a 9-week Iyengar yoga course on chronic non-specific neck pain. This secondary analysis uses linear mixed models to investigate the individual trajectories of pain intensity in participants before, during and after the Iyengar yoga course. Method: Participants with chronic non-specific neck pain were selected for the study. The participants suffered from neck pain for at least 5 days per week for at least the preceding 3 months, with a mean neck pain intensity (NPI) of 40 mm or more on a Visual Analog Scale of 100 mm. The participants were randomized to either a yoga group (23) or to a self-directed exercise group (24). The mean age of the participants in the yoga group was 46, and ranged from 19 to 59. The participants in the yoga group participated in an Iyengar yoga program designed to treat chronic non-specific neck pain. Our current analysis only includes participants who were initially randomized into the yoga group. The average weekly neck pain intensity at baseline, during and post intervention, comprising 11 total time points, was used to construct the growth models. We performed a step-up linear mixed model analysis to investigate change in NPI during the yoga intervention. We fit nested models using restricted maximum-likelihood estimation (REML), tested fixed effects with Wald test p-values and random effects with the likelihood ratio test. We constructed 10 REML models. Results: The model that fit the data best was an unconditional random quadratic growth model, with a first-order auto-regressive structure specified for the residual R matrix. Participants in the yoga group showed significant variation in NPI. They demonstrated variation in their intercepts, in their linear rates of change, and most tellingly, in their quadratic rates of change. Conclusions: While all participants benefitted from the yoga intervention, the degree to which they benefitted varied. Additionally, they did not experience a consistent rate of reduction in NPI − their NPI fluctuated, either increasing and then decreasing, or vice-versa. We comment on the clinical and research implications of our findings

Associated factors and consequences of risk of bias in randomized controlled trials of yoga: A systematic review

© 2015 Cramer et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Background: Bias in randomized controlled trials (RCTs) of complementary therapy interventions seems to be associated with specific factors and to potentially distort the studies' conclusions. This systematic review assessed associated factors of risk of bias and consequences for the studies' conclusions in RCTs of yoga as one of the most commonly used complementary therapies. Methods: Medline/PubMed, Scopus, IndMED and the Cochrane Library were searched through February 2014 for yoga RCTs. Risk of selection bias was assessed using the Cochrane tool and regressed to a) publication year; b) country of origin; c) journal type; and d) impact factor using multiple logistic regression analysis. Likewise, the authors' conclusions were regressed to risk of bias. Results: A total of 312 RCTs were included. Impact factor ranged from 0.0 to 39.2 (median = 1.3); 60 RCT (19.2%) had a low risk of selection bias, and 252 (80.8%) had a high or unclear risk of selection bias. Only publication year and impact factor significantly predicted low risk of bias; RCTs published after 2001 (adjusted odds ratio (OR) = 12.6; 95% confidence interval (CI) = 1.7, 94.0; p<0.001) and those published in journals with impact factor (adjusted OR = 2.6; 95%CI = 1.4, 4.9; p = 0.004) were more likely to have low risk of bias. The authors' conclusions were not associated with risk of bias. Conclusions: Risk of selection bias was generally high in RCTs of yoga; although the situation has improved since the publication of the revised CONSORT statement 2001. Pre-CONSORT RCTs and those published in journals without impact factor should be handled with increased care; although risk of bias is unlikely to distort the RCTs' conclusions

Quality of life and mental health in patients with chronic diseases who regularly practice yoga and those who do not: A case-control study

While clinical trials have shown evidence of efficacy of yoga in different chronic diseases, subjective health benefits associated with yoga practice under naturalistic conditions have not yet been investigated. The aim of this study was to investigate associations of regular yoga practice with quality of life and mental health in patients with chronic diseases. Using a case-control design, patients with chronic diseases who regularly practiced yoga were selected from a large observational study and compared to controls who did not regularly practice yoga and who were matched individually to each case on gender, main diagnosis, education, and age (within 5 years). Patients' quality of life (SF-36 questionnaire), mental health (Hospital Anxiety and Depression Scale), life satisfaction, and health satisfaction (Questionnaire for Life Satisfaction) were assessed. Patients who regularly practiced yoga (n=186) had a better general health status (P=0.012), a higher physical functioning (P=0.001), and physical component score (P=0.029) on the SF-36 than those who did not (n=186). No group differences were found for the mental scales of the SF-36, anxiety, depression, life satisfaction, or health satisfaction. In conclusion, practicing yoga under naturalistic conditions seems to be associated with increased physical health but not mental health in chronically diseased patients. © 2013 Holger Cramer et al