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Benavidez and Hart: Effects of Yoga on Measures of Health-related Quality of Life from SF-36 and SF-12 Assessments: A Systematic Review and Meta-analysis

Abstract

Objectives

Yoga is commonly being adopted and prescribed with the intent to increase a participant’s health-related quality of life. In practice, the current gold-standard health-related quality of life measurement tool is the SF-36 and SF-12 assessments. Therefore, it is important for yoga scientists and practitioners to understand yoga’s effects on health-related quality of life when in fact a gold-standard assessment is implemented. The purpose of this study was to employ systematic review and meta-analytic techniques to examine the effect of yoga on measures of health-related quality of life measured using only the SF-36/12 assessments.

Methods

A current (January 2007 to December 2016) systematic review of the Pubmed database was conducted and included studies that used yoga as an intervention with outcomes measures of health-related quality of life measured by the SF-36/12. Ten different measures were extracted from studies including eight dimension scores (physical functioning, bodily pain, physical role function, general health, mental health, emotional role function, social function, and vitality) and two summary scores (physical component and mental component). Ten different meta-analyses were performed using calculated standardized mean effect sizes and random effects models. Both moderator and sensitivity analyses were conducted.

Results

A total of 34 studies were included is the analyses with 185 independent effect sizes. Yoga intervention showed a significant positive effect on all ten measures of the SF-36/12. Effects ranged from 0.56 (0.39-0.73) to 0.28 (0.17-0.40). Yoga type (Hatha, Iyengar, Other) moderated the effects of yoga intervention on the mental component (p=.021), with Hatha yielding the greatest effects (ES=1.63, 0.61-2.65). The sensitivity analysis showed little to no bias in mean effect size estimates.

Conclusions

The meta-analytic evidence clearly supports the small-to-medium positive effects of yoga on health-related quality of life, as measured by the SF-36/12 assessments.

INTRODUCTION

The Hindu philosophy of yoga, originating during the second century B.C, is based on eight limbs of Ashtang yoga: 1) compromised of ethical disciplines, 2) individual observances, 3) posture, 4) breath control, 5) withdrawal of senses, 6) concentration, 7) meditation, and 8) enlightenment [1]. In western societies, the term yoga is now a general term that describes a practice which focuses on breathing techniques, postures, strengthening exercises, and meditation [2]. Many forms of yoga exist with some of the more popular being Hatha, Iyengar, and Vinyasa which all aim to promote physical and psychosocial conditioning with improved wellness [3]. Yoga has increasingly become popular as a form of medicine to treat and prevent certain diseases [4,5,6]. A review of several meta-analyses showed that yoga has a positive effect on physical fitness, metabolic function, and other physical health related outcomes [7]. In terms of mental health, yoga has shown to be an effective treatment for those suffering from clinically diagnosed major depression [8,9]. Studies have also shown that yoga can improve both physical and mental health in a variety of generally healthy yet diverse populations [10,11,12].
Another outcome measure of growing interest in medical research is health-related quality of life (HRQOL). HRQOL is defined as a multi-dimensional concept that includes domains related to physical, mental, emotional, and social functioning. It goes beyond direct measures of population health, life expectancy, and causes of death, and focuses on the impact health status has on quality of life [13]. HRQOL has become a routine measure for clinicians to use in order to evaluate the effects of a chronic disease or illness on their patients [14]. Similar to other outcome measures, yoga has also shown to improve measures of HRQOL. Several studies have shown yoga improves HRQOL in individuals with cancer, arthritis, and chronic bodily pain [15,16,17].
There are several HRQOL measurement tools that have been developed and used in physical activity-related research [18]. However, the more widely used assessment tool is the Medical Outcomes Study 36-Item Short Form Survey (SF-36). The SF-36 is a multipurpose health survey that consists of 36 questions and yields an eight-scale profile of scores as well as a physical and mental health summary measure [19]. The SF-36 is such a widely-used instrument because it was designed as a generic instrument that would be applicable to a wide range of types and severities of health conditions [20]. The SF-12 is a condensed version of the SF-36 which consists of only 12 questions and has demonstrated to be equally reliable and valid as the SF-36 in clinical and population based studies in the US and other countries [21].
The SF-36/12 uses multi-item scales to measure the following 8 dimensions that cover the major concepts of ones HRQOL [20]:
  • PF- Physical Functioning

  • BP-Bodily Pain

  • PRF-Physical Role Functioning (Role limitations due to physical health problems)

  • GH-General Health Perceptions

  • MH-General Mental Health

  • VT-Vitality, Energy, Fatigue

  • SF-Social Functioning

  • ERF- Emotional Role Functioning (Role limitations due to emotional problems)

There are two sets of scores that are derived from administration of the SF-36/12: a profile score for the 8 dimensions and two summary scores, one for the physical component (PCS) and the mental component (MCS) [19] The PCS summary score is made up of scores from the physical functioning (PF), bodily pain (BP), physical role function (PRF), and general health (GH) dimensions. The MCS summary score is made up of scores from the mental health (MH), emotional role function (ERF), social function (SF), and vitality (VT) dimensions [20].
Many meta-analysis have shown the potential benefits of yoga on measures of HRQOL in numerous clinical populations [22,23,24]. However, although there has been research done on the effects of yoga on measures of HRQOL, none to date have measured the overall effect size of yoga on HRQOL measured by the SF-36/12. Therefore, the purpose of this meta-analysis was to explore and analyze the effect of yoga on measures of HRQOL measured using only the SF-36 or SF-12.

METHODS

Literature Search

Two reviewers conducted a search in PubMed database for studies that were conducted using yoga as an intervention and HRQOL measured by the SF-36/12 as an outcome measure. The following keywords were used to conduct the search in PubMed: yoga (“health-related quality of life” or “sf-12” or “sf-36” or “sf-8” or PCS or MCS or HRQOL or “mental component” or “physical component”).

Inclusion and Exclusion Criteria

Following a search using the above keywords in PubMed, two reviewers independently analyzed the abstracts generated using the following inclusion criteria:
  • 1. Publication type: Included studies had to have been published in a peer-reviewed journal indexed in Pubmed.

  • 2. Date of study publication: Included studies had to have been published within the past 10 years. The search began in September of 2016 and continued till December of 2016 with the cutoff date of 2007.

  • 3. Type of design: Included studies had to be experimental in design and be either a randomized controlled trial or single group with pre- and post-intervention measurements.

  • 4. Types of Intervention: Interventions had to use yoga as the main exposure. Studies that used yoga with a combination of other exposures where yoga was not a dominant exposure were not included.

  • 5. HRQOL measure: Only yoga interventions that used the SF-36 or SF-12 were included.

If all inclusion criteria were met for a study based on review of its abstract, a full text of the study was retrieved for further evaluation. As well, if inclusion criteria were not able to be evaluated based on information given in an abstract, a full text of the study was retrieved. A second stage of independent reviews was then performed with all full-text articles by the same two reviewers. Studies were excluded at this point of the systematic review if 1) any of the inclusion criteria above were in fact not met or 2) it was apparent that the type of data analysis performed in the study was not conducive to a standardized mean difference meta-analysis.

Data Extraction

Data for each study was independently extracted by the two reviewers using the same spreadsheet template to assure consistency. The following data were extracted from each of the included studies: Last name of the first author, publication year, type of study design, SF-36/12 form used, SF-36/12 measures reported, intervention sample size, intervention mean age, gender of sample, duration of yoga intervention (months), days per week of yoga intervention, and the form of yoga. Depending on study specifics, the following additional data were extracted: pretest, posttest, or gain score means and standard deviations; test statistics; confidence intervals; or p-values. After all data were extracted, both data-sets were compared for uniformity. After both datasets were consistent, one final dataset was created to be used for the final analysis.

Statistical Analysis

Ten different meta-analyses were performed in total including one for each of the eight SF-36/12 dimensions and one for each of the SF-36/12 summary component scores. Each meta-analysis was performed using calculated standardized mean effect sizes and their standard errors [25]. Due to the large scope of studies included in the systematic review, studies representing different randomly drawn populations from a universe, it was assumed that true differences existed across effect sizes. In other words, it was assumed that different populations (e.g., diseased vs. non-diseased) experienced different effects due to yoga intervention. Therefore, random effects models were used for all analyses [26]. Forest plots were constructed to describe individual study-level effect sizes as well as each pooled effect size with 95% confidence interval (CI) [27]. To further describe variability in effect sizes, the Q statistic for heterogeneity, the tau-squared (τ2) representing the variance component, and I2 describing percent of heterogeneity were computed [28].
A moderator analysis was conducted for each meta-analysis and included the categorical factors of study design, gender, disease status, yoga type, and SF-36/12 form. Two continuous variables were also used in the moderator analyses and included intervention length and participant mean age. All moderator analyses were performed using random effects models with non-pooled variances (τ2) [29]. A Q statistic provided statistical evidence against homogeneity of effect sizes for each moderator analysis. Finally, a three-step sensitivity analysis was performed for each meta-analysis. First, Egger’s regression models were used for testing funnel plot asymmetry [30]. Second, a trim-and-fill method was used for estimating the number of effect sizes required to show a symmetric funnel plot [31]. This method also provided an estimated mean effect size with the imputed study effect sizes required to balance the funnel plots. And lastly, a leave-one-out analysis was performed by re-estimating the effect sizes once for each study deleted [32]. Both Comprehensive Meta-Analysis (CMA) and the R Metafor package were used for the analyses [33,34]. Significance was set to p<.05. Standardized mean difference effect size (ES) thresholds were set as follows: .20 (small), .50 (medium), .80 (large) [35].

RESULTS

The initial search found 114 abstracts with 54 identified for full-text retrieval. From the pool of full-text studies, after further review, an additional 20 studies were excluded. This resulted in 34 studies being included in the meta-analysis with 185 independent effect sizes. The number of effect sizes ranged from 16 to 24 across the ten SF-36/12 measures. Figure 1 summarizes the search strategy with inclusion and exclusion reasoning. Table 1 describes the 34 studies in terms of their characteristics [36-69].
Figure 2 contains study-level mean effect sizes with 95% CIs as well as the pooled mean effect size and 95% CI from the random effects model. Yoga intervention showed a significant positive effect on the SF-36/12 MCS (ES=0.56, 0.39-0.73). Figure 3 contains additional forest plot data for the four SF-36/12 mental health dimensions. Each of the four mental health dimensions were significantly affected by yoga intervention, with the smallest effect seen on ERF (ES=0.30, 0.14-0.46) and the largest effect seen on VT (ES=0.47, 0.22-0.73).
Figures 4 and 5 show similar random effects forest plot results for physical health measures. The pooled mean effect for yoga intervention on the SF-36/12 PCS was significant (ES=0.28, 0.13-0.44), although lower than that seen for the MCS. As well, all four physical health dimensions saw significant effects from yoga intervention, with the smallest effect seen on GH (ES=0.28, 0.17-0.40) and the largest effect seen on BP (ES=0.41, 0.23-0.58).
Table 2 contains additional statistical support for heterogeneity of effect sizes across the ten SF-36/12 measures. All Q statistics, testing against homogeneity, were significant (ps<.05). As well, I2 values were considerable with the smallest I2 seen for PF (35.4%) and the largest seen for VT (90.4%).
Table 3 displays results of the random effects moderator analysis on the MCS and mental health dimensions. Only a few factors showed significant Q statistics, indicating moderating effects. Namely, yoga type moderated the effect of yoga intervention on the MCS (p=.021), with Hatha yielding the greatest effects (ES=1.63, 0.61-2.65). As well, SF-36/12 form showed a significant moderating effect on VT (p=.026), with the SF-36 producing a significant effect (ES=0.50, 0.23-0.77) and the SF-12 producing no effect (ES=0.03, -0.29-0.35). For the continuous moderator analysis, length of yoga intervention significantly moderated MH (ES=0.03, 0.01-0.06) and VT (ES=0.06, 0.03-0.10) dimensions.
Table 4 displays similar random effects moderator analyses for the PCS and physical health dimensions. Only two factors showed significant Q statistics, both on the PRF dimension. Namely, for the gender analysis, studies with both sexes showed that yoga intervention significantly (p=.004) affected PRF (ES=0.37, 0.22-0.52) and had no effect in studies with females only (ES=0.00, -0.20-0.20). As well, SF-36/12 form showed a significant moderating effect on PRF (p=.028), with the SF-36 producing a relatively smaller effect (ES=0.28, 0.13-0.44) as compared to the SF-12 (ES=0.69, 0.36-1.01).
The sensitivity analysis, in whole, showed little to no bias in mean effect size estimates. Egger’s regression test for funnel plot asymmetry showed only one significant Z statistic (p<.001), which was for the MCS. However, the trim-and-fill analysis for the MCS, after imputing four effect sizes, re-estimated an effect that remained significant (ES=0.44, 0.24-0.63). The leave-one-out analysis, as well, indicated robust findings. All lower-bound effect sizes remained significant, with the lowest lower-bound effect seen for the ERF dimension (ES=0.25, 0.11-0.39).

DISCUSSION

The purpose of this research was to perform a systematic review and meta-analysis of published studies from peer-reviewed journals that examined the effects of yoga intervention on measures of HRQOL assessed by the gold-standard SF-36/12 instruments. The primary aim was to evaluate the extent to which yoga intervention affects SF-36/12 measures. Results clearly showed that yoga has a positive effect on HRQOL as measured by the SF-36/12. These results were consistent across both mental and physical health domains. Using the previously mentioned strength effect size thresholds of .2 for small, .5 for medium, and .8 for large, results here support small- to medium-sized HRQOL effects from yoga. These effects remained robust after controlling for both selection bias and any specific study’s influence on the meta-analyses.
Results of this research are also consistent with other meta-analyses examining yoga’s effect on HRQOL. One such meta-analysis indicated that yoga improved psychological health in cancer patients more so than control [22]. However, that analysis was limited to a single measure of HRQOL as well as limited to a specific study population. Another meta-analysis, examining yoga’s effect on the two SF-36 component scores, showed positive effects in favor of yoga for both measures [70]. However, that systematic review was limited to studies published no later than 2010 and was also limited to the two component scores only. A final, and more recent meta-analysis, examined yoga’s pooled effects on HRQOL among women with breast cancer [24]. Although an overall yoga and HRQOL effect was noted in this study, final results were mixed due to positive effects seen by the control over yoga on physical health.
The secondary aim of this study was to determine the extent to which study-level factors and covariates explained heterogeneity across yoga intervention effect sizes. Despite clear heterogeneity, as shown by significant tests of homogeneity (Q statistics), these results were unable to explain such variance. This may be due in part to the imprecise nature of study-level data extracted from articles over that of more precise individual-level data.
This research has limitations that should be considered along with its implications. First, and primary, is the inability of the researchers in all included studies to “blind” yoga participants to their intervention treatment. With yoga intervention participants aware of their treatment, there is no way to remove subject-expectations as a potential threat to internal validity [71]. That is, there is no way to rule out the possibility that yoga participants responded more favorably to follow-up SF-36/12 assessments merely because they knew they were receiving yoga treatment. Second, there were no unpublished or non-peer-reviewed studies included in this systematic review. Excluding these studies are thought to lead to publication bias and in turn cause asymmetric funnel plots [72]. Publication bias was, however, not found to be an issue in this meta-analysis. Moreover, studies that are unpublished are more likely to be of low methodological quality and therefore less useful in terms of unbiased generalizations [73]. A last limitation of this research was the imprecise measurement of yoga treatment. At best, studies included in this meta-analysis reported yoga intervention type (e.g., Hatha), duration (i.e., 30 minutes) and length (i.e., 4 weeks). This type of intervention reporting does not allow for a precise yoga dose measurement. It is of standard practice that physical activity interventions use stringent measurement protocols so as to properly evaluate the effects due to specific doses of activity [74].
There are many strengths, however, associated with this research that are worth mentioning. First, to date, there are no PubMed published studies that have meta-analyzed the effects of yoga intervention on HRQOL specifically assessed by the SF-36/12 set of instruments. This feature adds strength to this research because the SF-36/12 tools are widely known, extensively used, and possess strong psychometric properties [75]. Results from this meta-analysis, showing clear evidence in support of yoga’s positive effect on HRQOL, therefore, have the added value of strong internal validity due to the use of a gold-standard assessment. A second strength of this study is that it included the analysis of ten (10) different HRQOL measures, representing both mental and physical health domains. Since all ten (10) measures showed positive mean effect sizes, results from this meta-analysis have the added assurance of robust generalizations.

CONCLUSIONS

In conclusion, this study performed a systematic review that resulted in the meta-analysis of 185 effect sizes, extracted from 34 published studies, representing ten (10) different SF-36/12 measures of HRQOL. The meta-analytic evidence clearly supports the small-to-medium positive effects of yoga on HRQOL. These effects remained consistent after controlling for various forms of bias. It is suggested that yoga interventions include more precise yoga dosage measurement, as this may in part explain differences in the effects seen.

Notes

Conflicts of interest

The authors declare no conflicts of interest.

Figure 1.
Schematic depiction of search strategy.
em-1-5f1.tif
Figure 2.
Forest plot of MCS effect sizes and random effects (RE) pooled estimate.
em-1-5f2.tif
Figure 3.
Forest plots of effect sizes and random effects (RE) pooled estimates across mental health dimensions.
em-1-5f3.tif
Figure 4.
Forest plot of PCS effect sizes and random effects (RE) pooled estimate.estimates across mental health dimensions.
em-1-5f4.tif
Figure 5.
Forest plots of effect sizes and random effects (RE) pooled estimates across physical health dimensions.
em-1-5f5.tif
Table 1.
Characteristics of included studies
First Author, Year HRQOL Measure Study Design SF-36/12 Form Mean Age (years) Gender Diseased Population Yoga Duration (weeks) Type of Yoga
Banth, 2015 MCS, PCS RCT SF-12 38 Female Yes 8 Non-Specific
Cade, 2010 BP, ERF, GH, MH, PF, PRF, SF, VT RCT SF-36 45 Both Yes 20 Vinyasa
Chandwani, 2014 BP GH, MCS, PCS, PF, PRF RCT SF-36 52.38 Female Yes 6 Non-Specific
Chinnaiyan, 2015 BP ERF, GH, MH, PF, SF, VT, PCS, MCS Pre-Post SF-36 59 Both No 12 Non-Specific
Cox, 2010 MCS, PCS RCT SF-12 39 Both Yes 12 Iyengar
Cramer, 2013 (a) BP, ERF, GH, MH, PF, PRF, SF, VT, PCS, MCS RCT SF-36 46.2 Both Yes 9 Iyengar
Cramer, 2013 (b) BP, ERF, GH, MH, PF, PRF, SF, VT, PCS, MCS Pre-Post SF-36 47.8 Both No 9 Iyengar
Cuenco, 2009 MCS, PCS RCT SF-36 72.2 Both Yes 12 Iyengar
Danhuer, 2009 MCS, PCS RCT SF-12 54.3 Female Yes 10 Hatha
Ebnezar, 2011 BP, ERF, GH, MH, PF, PRF, SF, VT RCT SF-36 59.56 Both Yes 10 Non-Specific
Evans, 2013 BP, GH, MH, VT RCT SF-36 29.9 Female Yes 6 Iyengar
Evans, 2014 PF RCT SF-36 19 Both Yes 6 Iyengar
Fouladbakhsh, 2014 MCS, PCS Pre-Post SF-36 67 Both Yes 8 Hatha
Garg, 2015 MCS, PCS Pre-Post SF-12 46.18 Both Yes 1 Non-Specific
Groessl, 2008 MCS, PCS RCT SF-36 55.3 Both Yes 10 Non-Specific
Groessl, 2012 MCS, PCS Pre-Post SF-12 57.2 Male Yes 10 Hatha
Hadi, 2007 BP, ERF, GH, MH, PF, PRF, SF, VT, PCS, MCS Pre-Post SF-36 33 Both No 24 Hatha
Halpern, 2014 ERF, GH, PRF, SF, VT RCT SF-36 74.66 Both Yes 12 Hatha
Kinser,2014 MCS RCT SF-12 40.9 Female Yes 8 Hatha
Kligler, 2011 BP, ERF, GH, MH, PF, PRF, SF, VT, PCS, MCS RCT SF-12 45.7 Both Yes 6 Non-Specific
Lakkireddy, 2013 ERF, GH, MH, PF, VT Pre-Post SF-36 61 Both Yes 12 Iyengar
Lau, 2015 BP, ERF, GH, MH, PF, PRF, SF, VT, PCS, MCS RCT SF-36 52.44 Both Yes 12 Iyengar
Lindahl, 2016 MCS, PCS Pre-Post SF-12 66.5 Both No 7 Hatha
Martin, 2014 BP, ERF, GH, MH, PF, PRF, SF, VT, PCS, MCS Pre-Post SF-36 41 Both No 12 Vinyasa
Moonaz, 2015 BP, ERF, GH, MH, PF, PRF, SF, VT, PCS, MCS RCT SF-36 49.2 Both Yes 8 Hatha
Nickolson, 2014 BP, ERF, GH, MH, PF, PRF, SF, VT, PCS, MCS RCT SF-36 66 Both No 12 Non-Specific
Phoosuwan, 2009 BP, ERF, GH, MH, PF, PRF, SF, VT RCT SF-36 54.32 Female No 12 Weight Bearing
Ratcliff, 2016 MCS, PCS RCT SF-36 52.4 Female Yes 6 Non-Specific
Sareen, 2007 BP, ERF, GH, MH, PF, PRF, SF, VT RCT SF-36 50 Both Yes 12 Iyengar
Sharma, 2015 MCS, PCS RCT SF-36 62.8 Both Yes 12 Hatha
Smith, 2007 BP, ERF, GH, MH, PF, PRF, SF, VT RCT SF-36 44 Both No 10 Hatha
Telles, 2012 MCS, PCS RCT SF-12 33 Both No 1 Non-Specific
Tsai, 2016 BP, ERF, GH, MH, PF, PRF, SF, VT Pre-Post SF-36 34 Female No 12 Non-Specific
Wahlstrom, 2016 MCS, PCS RCT SF-36 64 Both Yes 12 Non-Specific

BP, Bodily Pain; ERF, Emotional Role Functioning; GH, General Health; MH, Mental Health; PF, Physical Functioning; PRF, Physical Role Functioning; RCT, Randomized Control; SF, Social Functioning; VT, Vitality; MCS, Mental Component Score; PCS, Physical Component Score.

Table 2.
Summary results and variance components across SF-36/12 component scores and dimensions.
HRQOL measure N ES 95% CI τ2 I2 Q
Mental
 MCS 24 .56 .39, .73 .12 78.0 104.6
 ERF 17 .30 .14, .46 .08 76.4 67.8
 MH 17 .44 .27, .60 .08 75.1 64.4
 VT 18 .47 .22, .73 .27 90.4 176.7
 SF 16 .40 .25, .56 .06 71.4 52.5
Physical
 PCS 23 .28 .13, .44 .09 73.3 82.5
 BP 17 .41 .23, .58 .09 77.4 70.6
 GH 19 .28 .17, .40 .03 54.7 39.7
 PRF 16 .31 .16, .46 .06 69.3 48.9

Q statistics (with N-1 df) test for heterogeneity. All Q p-values were significant at p<.001. τ2 represents variance components. I2 represents percent of heterogeneity.

Table 3.
Effect size by moderator for the SF-36/12 MCS and mental health dimensions.
Moderator ESMCS 95% CI ESMH 95% CI ESSF 95% CI ESERF 95% CI ESVT 95% CI
Designa
 PP .57 .31, .83 .43 .06, .80 .38 .00, .76 .36 -.01, .72 .54 .15, 1.23
 RCT .57 .33, .81 .38 .26, .49 .39 .25, .53 .26 .11, .41 .36 .24, .49
p .981 .801 .949 .636 .614
Gendera
 Female 1.23 .44, 2.02 .34 -.05, .74 .26 -.036, .89 .11 -.41, .63 .52 -.18, 1.21
 Male .37 .09, .65 NA NA NA NA NA NA NA NA
 Both .49 .32, .66 .45 .27, .64 .43 .27, .59 .32 .15, .49 .47 .18, .75
p .133 .621 .608 .441 .896
Diseaseda
 Yes .54 .33, .74 .38 .26, .51 .41 .25, .57 .27 .14, .39 .35 .23, .46
 No .61 .29, .94 .45 .13, .78 .38 .09, .67 .36 .01, .71 .61 00, 1.21
p .687 .688 .851 .626 .406
Yogaa
 Hatha 1.63 .61, 2.65 .71 .21, 1.22 .43 -.01, .88 .29 -.20, .78 .79 -.29, 1.86
 Iyengar .21 -.09, .50 .36 .15, .58 .48 .17, .78 .15 -.11, .40 .36 .21, .52
 Other .46 .34, .59 .32 .20, .44 .33 .17, .49 .37 .17, .57 .35 .13, .56
p .021 .325 .658 .393 .732
Forma
 SF-36 .46 .24, .68 .45 .28, .63 .39 .22, .55 .30 .12, .47 .50 .233, .77
 SF-12 .76 .45, 1.07 .24 -.08, .55 .64 .32, .97 .37 .05, .69 .03 -.29, .35
p .126 .249 .169 .687 .026
Lengthb .02 -.02, .06 .03 .01, .06 .01 -.02, .04 .02 -.01, .06 .06 .03, .10
p .290 .003 .450 .150 .001
Ageb -.01 -.03, .01 -.01 -.02, .01 .00 -.02, .01 .00 -.01, .02 -.01 -.03, .02
p .259 .570 .670 .810 .535

All moderator analyses were performed using random effects models with non-pooled variances (tau-squared).

a These moderators are treated as categorical with group-specific mean effect sizes reported.

b These moderators are treated as continuous with meta-regression coefficients reported.

p-values in bold are significant at p<.05. NA indicates no studies contributing to that group.

Table 4.
Effect size by moderator for the SF-36/12 PCS and physical health dimensions.
Moderator ESPCS 95% CI ESBP 95% CI ESGH 95% CI ESPRF 95% CI ESPF 95% CI
Designa
 PP .23 -.08, .54 .30 -.07, .66 .22 -.03, .48 .20 -.24, .64 .24 .02, .45
 RCT .32 .17, .46 .44 .24, .65 .30 .18, .42 .34 .20, .47 .37 .27, .47
p .624 .481 .592 .571 .265
Gendera
 Female .24 -.14, .61 .33 .08, .59 .34 -.05, .73 .00 -.20, .20 .29 .09, .49
 Male .03 -.25, .29 NA NA NA NA NA NA NA NA
 Both .32 .14, .49 .42 .21, .64 .29 .17, .41 .37 .22, .52 .34 .22, .45
p .203 .584 .808 .004 .685
Diseaseda
 Yes .31 .16, .47 .45 .23, .67 .32 .23, .42 .37 .21, .52 .40 .30, .50
 No .15 -.20, .50 .34 .03, .65 .22 -.04, .48 .21 -.10, .53 .20 -.01, .42
p .406 .559 .486 .395 .107
Yogaa
 Hatha .87 .06, 1.69 .37 -.44, 1.17 .21 -.16, .58 .37 .00, .74 .30 -.19, .80
 Iyengar .32 .12, .52 .49 .22, .77 .38 .24, .52 .32 .12, .52 .38 .20, .56
 Other .20 .05, .36 .33 .10, .56 .23 .06, .40 .26 .04, .48 .29 .19, .40
p .217 .666 .348 .857 .723
Forma
 SF-36 .29 .05, .53 .41 .22, .60 .29 .17, .41 .28 .13, .44 .32 .22, .43
 SF-12 .29 .13, .44 .37 .05, .69 .14 -.17, .46 .69 .36, 1.01 .53 .21, .85
p .979 .837 .393 .028 .231
Lengthb .01 -.02, .03 .02 -.01, .05 .01 -.01, .03 .01 -.02, .04 .01 -.03, .03
p .709 .177 .320 .615 .352
Ageb -.01 -.03, .00 -.01 -.03, .01 .00 -.01, .01 .00 -.01, .01 -.01 -.02, .00
p .058 .502 .820 .989 .154

All moderator analyses were performed using random effects models with non-pooled variances (tau-squared).

a These moderators are treated as categorical with group-specific mean effect sizes reported.

b These moderators are treated as continuous with meta-regression coefficients reported.

p-values in bold are significant at p<.05. NA indicates no studies contributing to that group.

Table 5.
Sensitivity analysis of effect sizes across SF-36/12 component scores and dimensions.
Asymmetrya
Trim-and-fillb
Leave-one-outc
HRQOL measure Z p #d ESe 95% CI ESLf 95% CI ESHg 95% CI
Mental
 MCSh 3.48 <.001 4 .44 .24, .63 .49 .35, .64 .59 .42, .76
 ERF 1.42 .157 4 .19 .01, .38 .25 .11, .39 .33 .17, .49
 MH 0.98 .328 6 .30 .11, .49 .35 .24, .45 .46 .30, .63
 VT 0.70 .484 0 .47 .22, .73 .33 .21, .45 .51 .24, .78
 SF 0.59 .556 0 .41 .25, .56 .37 .22, .52 .44 .29, .59
Physical
 PCS 0.49 .624 0 .28 .13, .44 .26 .10, .41 .32 .17, .47
 BP 1.55 .120 0 .41 .24, .58 .35 .19, .50 .44 .27, .62
 GH 0.73 .468 2 .25 .14, .37 .25 .14, .37 .31 .20, .42
 PRF -0.30 .763 0 .31 .16, .46 .27 .14, .41 .35 .20, .49
 PF -0.92 .359 5 .43 .31, .54 .31 .21, .41 .36 .26, .46

a Egger's regression models for testing funnel plot asymmetry.

Trim-and-fill method for estimating the number of effect sizes required to show a symmetric funnel plot.

c Leave-one-out analysis re-estimating the effect sizes once for each study deleted.

d Number of effect sizes needed to balance the funnel plot.

e Estimated mean effect size with imputed study effect sizes needed to balance funnel plot.

f Lowest ES seen from leave-one-out analysis.

g Highest effect size seen from leave-one-out analysis.

h Test of asymmetry was nonsignificant (Z=1.68, p=.092) with Kinser, 2014 omitted.

REFERENCES

1. Khanna S, Greeson JM. A narrative review of yoga and mindfulness as complementary therapies for addiction. Complement Ther Med 2013; 21:244–52.
crossref pmid pmc
2. Ospina , Maria & University of Alberta Evidence-based Practice Center & United States. Agency for Healthcare Research and Quality (2007). Meditation practices for health: state of the research AHRQ Rockville, MD
3. Buffart LM, Van Uffelen JG, Riphagen II, Brug J, van Mechelen W, Brown WJ, Chinapaw MJ. Physical and psychosocial benefits of yoga in cancer patients and survivors, a systematic review and meta-analysis of randomized controlled trials. BMC Cancer 2012; 12:559
crossref pmid pmc pdf
4. Groessl EJ, Weingart KR, Johnson N, Baxi S. The benefits of yoga for women veterans with chronic low back pain. J Altern Complement Med 2012; 18:832–8.
crossref pmid
5. Alexander GK, Innes KE, Selfe TK, Brown CJ. “More than I expected”: Perceived benefits of yoga practice among older adults at risk for cardiovascular disease. Complement Ther Med 2013; 21:14–28.
crossref pmid
6. Silverthorne C, Khalsa SB, Gueth R, DeAvilla N, Pansini J. Respiratory, physical, and psychological benefits of breath-focused yoga for adults with severe traumatic brain injury (TBI): a brief pilot study report. Int J Yoga Therap 2012; 22:47–52.
7. Büssing A, Michalsen A, Khalsa SB, Telles S, Sherman KJ. Effects of yoga on mental and physical health: a short summary of reviews. Evid Based Complement Alternat Med 2012; 2012:165410
crossref pmid pmc pdf
8. Prathikanti S, Rivera R, Cochran A, Tungol JG, Fayazmanesh N, Weinmann E. Treating major depression with yoga: A prospective, randomized, controlled pilot trial. PloS One 2017; 12:e0173869.
crossref pmid pmc
9. Naveen GH, Thirthalli J, Rao MG, Varambally S, Christopher R, Gangadhar BN. Positive therapeutic and neurotropic effects of yoga in depression: A comparative study. Indian J Psychiatry 2013; 55:S400–4.
pmid pmc
10. Tran MD, Holly RG, Lashbrook J, Amsterdam EA. Effects of Hatha yoga practice on the health-related aspects of physical fitness. Prev Cardiol 2001; 4:165–70.
crossref pmid
11. Gururaja D, Harano K, Toyotake I, Kobayashi H. Effect of yoga on mental health: Comparative study between young and senior subjects in Japan. Int J Yoga 2011; 4:7–12.
crossref pmid pmc
12. Bhat PS, Chopra V, Mehta SG, Srivastava K, Kumar SR, Prakash J. Psychological benefits of yoga in industrial workers. Ind Psychiatry J 2012; 21:98–103.
crossref pmid pmc
13. Health-Related Quality of Life and Well-Being [Internet]. Health-Related Quality of Life and Well-Being | Healthy People 2020. Office of Disease Prevention and Health Promotion. Available from: https://www.healthypeople.gov/2020/about/foundation-health-measures/Health-Related-Quality-of-Life-and-Well-Being(Accessed May 4, 2017)
14. Ghosh RK, Ghosh SM, Ganguly G. Health-related quality of life and its growing importance in clinical practise. N Z Med J 2010; 123:99–101.
15. Mishra SI, Scherer RW, Snyder C, Geigle PM, Berlanstein DR, Topaloglu O. Exercise interventions on health-related quality of life for people with cancer during active treatment. Cochrane Database of Systematic Reviews. John Wiley & Sons, Ltd 2012.
16. Evans S, Moieni M, Lung K, Tsao J, Sternlieb B, Taylor M, Zeltzer L. Impact of iyengar yoga on quality of life in young women with rheumatoid arthritis. Clin J Pain 2013; 29:988–97.
crossref pmid pmc
17. Saper RB, Sherman KJ, Cullum-Dugan D, Davis RB, Phillips RS, Culpepper L. Yoga for chronic low back pain in a predominantly minority population: a pilot randomized controlled trial. Altern Ther Health Med 2009; 15:18–27.
pmc
18. Hart PD, Kang M, Weatherby NL, Lee YS, Brinthaupt TM. Systematic Review of Health-Related Quality of Life Assessments in Physical Activity Research. World J Prev Med 2015; 3:28–39.
19. Ware Jr JE. SF-36 health survey update. Spine 2000; 25:3130–9.
crossref pmid
20. McDowell I. Measuring health: a guide to rating scales and questionnaires. Oxford university press 2006.
21. Larson CO. Use of the SF-12 instrument for measuring the health of homeless persons. Health Serv Res 2002; 37:733–50.
crossref pmid pmc
22. Lin KY, Hu YT, Chang KJ, Lin HF, Tsauo JY. Effects of yoga on psychological health, quality of life, and physical health of patients with cancer: a meta-analysis. Evid Based Complement Alternat Med 2011; 2011:659876
crossref pmid pmc pdf
23. Ward L, Stebbings S, Cherkin D, Baxter GD. Yoga for Functional Ability, Pain and Psychosocial Outcomes in Musculoskeletal Conditions: A Systematic Review and Meta-Analysis. Musculoskeletal Care 2013; 11:203–17.
crossref pmid
24. Pan Y, Yang K, Wang Y, Zhang L, Liang H. Could yoga practice improve treatment-related side effects and quality of life for women with breast cancer? A systematic review and meta-analysis. Asia Pac J Clin Oncol 2015; 13:e79–e95.
crossref pmid
25. Mark W, Lipsey , Wilson DB. Practical meta-analysis. Thousand Oaks, CA: Sage Publications 2001.
26. Borenstein M, Hedges LV, Higgins J, Rothstein HR. A basic introduction to fixed-effect and random-effects models for meta-analysis. Res Synth Methods 2010; 1:97–111.
crossref pmid
27. Lewis S, Clarke M. Forest plots: trying to see the wood and the trees. BMJ 2001; 322:1479–80.
crossref pmid pmc
28. Borenstein M, Hedges L, Rothstein H. Meta-analysis: Fixed effect vs. random effects. Meta-analysis.com 2007.
29. Borenstein M, Hedges LV, Higgins J, Rothstein HR. Introduction to Meta-Analysis. John Wiley & Sons, Ltd 2009.
30. Egger M, Smith GD, Schneider M, Minder C. Bias in meta-analysis detected by a simple, graphical test. BMJ 1997; 315:629–34.
crossref pmid pmc
31. Duval S, Tweedie R. Trim and fill: a simple funnel-plot–based method of testing and adjusting for publication bias in meta-analysis. Biometrics 2000; 56:455–63.
crossref pmid
32. Patsopoulos NA, Evangelou E, Ioannidis JP. Sensitivity of between-study heterogeneity in meta-analysis: proposed metrics and empirical evaluation. Int J Epidemiol 2008; 37:1148–57.
crossref pmid pdf
33. Del Re AC. A practical tutorial on conducting meta-analysis in R. The Quantitative Methods for Psychology 2015; 11:37–50.
crossref
34. Borenstein M, Hedges L, Higgins J, Rothstein H. Comprehensive meta-analysis version 2. Englewood, NJ: Biostat 2005.
35. Cohen J. Statistical power analysis for the behavioral sciences Lawrence Earlbaum Associates Publisher. Hillsdale, NJ 1988.
36. Banth S, Ardebil MD. Effectiveness of mindfulness meditation on pain and quality of life of patients with chronic low back pain. Int J Yoga 2015; 8:128–33.
crossref pmid pmc
37. Cade WT, Reeds DN, Mondy KE, et al. Yoga lifestyle intervention reduces blood pressure in HIV-infected adults with cardiovascular disease risk factors. HIV Med 2010; 11:379–88.
crossref pmid pmc
38. Chandwani KD, Perkins G, Nagendra HR, et al. Randomized, controlled trial of yoga in women with breast cancer undergoing radiotherapy. J Clin Oncol 2014; 32:1058–65.
crossref pmid pmc
39. Chinnaiyan KM, DePetris AM, Boura JA, Stakich-Alpirez K, Billecke SS. Feasibility of Establishing a Comprehensive Yoga Program and its Dose-Effect Relationship on Cardiovascular Risk Factors and Wellness Parameters: A Pilot Study. Int J Yoga Therap 2015; 25:135–40.
crossref pmid
40. Cox H, Tilbrook H, Aplin J, et al. A randomised controlled trial of yoga for the treatment of chronic low back pain: results of a pilot study. Complement Ther Clin Pract 2010; 16:187–93.
crossref pmid
41. Cramer H, Lauche R, Hohmann C, et al. Randomized-controlled trial comparing yoga and homebased exercise for chronic neck pain. Clin J Pain 2013; 29:216–23.
crossref pmid
42. Cramer H, Lauche R, Hohmann C, Langhorst J, Dobos G. Yoga for Chronic Neck Pain: A 12-Month Follow-Up. Pain Med 2013; 14:541–8.
crossref pmid pdf
43. Cuenco D, Nguyen HQ, Paul S, Carrieri-Kohlman V. Yoga therapy decreases dyspnea-related distress and improves functional performance in people with chronic obstructive pulmonary disease: a pilot study. J Altern Complement Med 2009; 15:225–34.
crossref pmid pmc
44. Danhauer SC, Mihalko SL, Russell GB, et al. Restorative yoga for women with breast cancer: findings from a randomized pilot study. Psychooncology 2009; 18:360–8.
crossref pmid pmc
45. Ebnezar J, Nagarathna R, Bali Y, Nagendra HR. Effect of an integrated approach of yoga therapy on quality of life in osteoarthritis of the knee joint: A randomized control study. Int J Yoga 2011; 4:55
crossref pmid pmc
46. Evans S, Moieni M, Lung K, et al. Impact of iyengar yoga on quality of life in young women with rheumatoid arthritis. Clin J Pain 2013; 29:988–97.
crossref pmid pmc
47. Evans S, Lung KC, Seidman LC, Sternlieb B, Zeltzer LK, Tsao JC. Iyengar yoga for adolescents and young adults with irritable bowel syndrome. J Pediatr Gastroenterol Nutr 2014; 59:244–53.
crossref pmid pmc
48. Fouladbakhsh JM, Davis JE, Yarandi HN. A pilot study of the feasibility and outcomes of yoga for lung cancer survivors. Oncol Nurs Forum 2014; 41:162–74.
crossref pmid pdf
49. Garg S, Ramya CS, Shankar V, Kutty K. Efficacy of short-term Yoga therapy program on quality of life in patients with psychosomatic ailments. Indian J Psychiatry 2015; 57:78–80.
crossref pmid pmc
50. Groessl EJ, Weingart KR, Aschbacher K, Pada L, Baxi S. Yoga for veterans with chronic low-back pain. J Altern Complement Med 2008; 14:1123–9.
crossref pmid
51. Groessl EJ, Weingart KR, Johnson N, Baxi S. The benefits of yoga for women veterans with chronic low back pain. J Altern Complement Med 2012; 18:832–8.
crossref pmid
52. Hadi N, Hadi N. Effects of hatha yoga on well-being in healthy adults in Shiraz, Islamic Republic of Iran. East Mediterr Health J 2007; 13:829–37.
pmid
53. Halpern J, Cohen M, Kennedy G, Reece J, Cahan C, Baharav A. Yoga for improving sleep quality and quality of life for older adults. Altern Ther Health Med 2014; 20:37–46.
pmid
54. Kinser PA, Elswick RK, Kornstein S. Potential longterm effects of a mind-body intervention for women with major depressive disorder: sustained mental health improvements with a pilot yoga intervention. Arch Psychiatr Nurs 2014; 28:377–83.
crossref pmid pmc
55. Kligler B, Kenney J, Levenson H, Merrell W. Randomized trial of the effect of an integrative medicine approach to the management of asthma in adults on disease-related quality of life and pulmonary function. Altern Ther Health Med 2011; 17:10–5.
56. Lakkireddy D, Atkins D, Pillarisetti J, et al. Effect of yoga on arrhythmia burden, anxiety, depression, and quality of life in paroxysmal atrial fibrillation: the YOGA My Heart Study. J Am Coll Cardiol 2013; 61:1177–82.
crossref pmid
57. Lau C, Yu R, Woo J. Effects of a 12-week hatha yoga intervention on metabolic risk and quality of life in Hong Kong Chinese adults with and without metabolic syndrome. PloS One 2015; 10:e0130731.
crossref pmid pmc
58. Lindahl E, Tilton K, Eickholt N, Ferguson-Stegall L. Yoga reduces perceived stress and exhaustion levels in healthy elderly individuals. Complement Ther Clin Pract 2016; 24:50–6.
crossref pmid
59. Martin AC, Keats MR. The impact of yoga on quality of life and psychological distress in caregivers for patients with cancer. Oncol Nurs Forum 2014; 41:257–64.
crossref pmid pdf
60. Moonaz SH, Bingham CO, Wissow L, Bartlett SJ. Yoga in sedentary adults with arthritis: effects of a randomized controlled pragmatic trial. J Rheumatol 2015; 42:1194–202.
crossref pmid pmc
61. Nicholson VP, McKean MR, Burkett BJ. Twelve weeks of BodyBalance® training improved balance and functional task performance in middle-aged and older adults. Clin Interv Aging 2014; 9:1895–904.
crossref pmid pmc
62. Phoosuwan M, Kritpet T, Yuktanandana P. The effects of weight bearing yoga training on the bone resorption markers of the postmenopausal women. J Med Assoc Thai 2009; 92:S102–8.
pmid
63. Ratcliff CG, Milbury K, Chandwani KD, et al. Examining mediators and moderators of yoga for women with breast cancer undergoing radiotherapy. Integr Cancer Ther 2016; 15:250–62.
crossref pmid pmc
64. Sareen S, Kumari V, Gajebasia KS, Gajebasia NK. Yoga: a tool for improving the quality of life in chronic pancreatitis. World J Gastroenterol 2007; 13:391–7.
crossref pmid pmc
65. Sharma NK, Robbins K, Wagner K, Colgrove YM. A randomized controlled pilot study of the therapeutic effects of yoga in people with Parkinson’s disease. Int J Yoga 2015; 8:74–9.
crossref pmid pmc
66. Smith C, Hancock H, Blake-Mortimer J, Eckert K. A randomised comparative trial of yoga and relaxation to reduce stress and anxiety. Complement Ther Med 2007; 15:77–83.
crossref pmid
67. Telles S, Singh N, Yadav A, Balkrishna A. Effect of yoga on different aspects of mental health. Indian J Physiol Pharmacol 2012; 56:245–54.
pmid
68. Tsai SY. Effect of Yoga Exercise on Premenstrual Symptoms among Female Employees in Taiwan. Int J Environ Res Public Health 2016; 13:721
crossref pmc
69. Wahlstrom M, Rydell Karlsson M, Medin J, Frykman V. Effects of yoga in patients with paroxysmal atrial fibrillation–a randomized controlled study. Eur J Cardiovasc Nurs 2017; 16:57–63.
crossref pmid
70. Patel NK, Newstead AH, Ferrer RL. The effects of yoga on physical functioning and health related quality of life in older adults: a systematic review and meta-analysis. J Altern Complement Med 2012; 18:902–17.
crossref pmid
71. Supino PG, Borer JS. Principles of research methodology: A guide for clinical investigators. Springer Science & Business Media 2012.
72. Egger M, Juni P, Bartlett C, Holenstein F, Sterne J. How important are comprehensive literature searches and the assessment of trial quality in systematic reviews? Empirical study. Health Technol Assess 2013; 7:1–76.
73. Higgins JP, Green S. Chapter 10.3.2: Including unpublished studies in systematic reviews. Cochrane handbook for systematic reviews of interventions. John Wiley & Sons 2011.
74. Welk G. Physical activity assessments for health-related research. Human Kinetics 2002.
75. Hart PD, Kang M. Reliability of the Short-Form Health Survey (SF-36) in Physical Activity Research Using Meta-Analysis. World J Prev Med 2015; 3:17–23.
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