The Benefits of Yoga for Women Veterans with Chronic Low Back Pain

Abstract

Objectives:

Chronic low back (CLBP) pain is prevalent among military veterans and often leads to functional limitations, psychologic symptoms, lower quality of life, and higher health care costs. An increasing proportion of U.S. veterans are women, and women veterans may have different health care needs than men veterans. The purpose of this study was to assess the impact of a yoga intervention on women and men with CLBP.

Subjects/setting/intervention:

VA patients with CLBP were referred by primary care providers to a clinical yoga program.

Design:

Research participants completed a brief battery of questionnaires before their first yoga class and again 10 weeks later in a single-group, pre–post study design.

Outcome measures

: Questionnaires included measures of pain (Pain Severity Scale), depression (CESD-10), energy/fatigue, and health-related quality of life (SF-12). Yoga attendance and home practice of yoga were also measured. Repeated-measures analysis of variance was used to analyze group differences over time while controlling for baseline differences.

Results:

The 53 participants who completed both assessments had a mean age of 53 years, and were well educated, 41% nonwhite, 49% married, and had varying employment status. Women participants had significantly larger decreases in depression (p=0.046) and pain “on average” (p=0.050), and larger increases in energy (p=0.034) and SF-12 Mental Health (p=0.044) than men who participated. The groups did not differ significantly on yoga attendance or home practice of yoga.

Conclusions:

These results suggest that women veterans may benefit more than men veterans from yoga interventions for chronic back pain. Conclusions are tentative because of the small sample size and quasi-experimental study design. A more rigorous study is being designed to answer these research questions more definitively.

Introduction

C hronic Low back pain (CLBP) afflicts 25% of people in the United States,¹ and evidence suggests the rate may be increasing.² In addition to the discomfort of pain itself, persons with CLBP are more likely to experience psychologic symptoms such as anxiety^3,4 and depression,^5,6 and have functional limitations that result in lower productivity⁷ and lower health-related quality of life.^8,9 Not surprisingly, people with CLBP have higher mean health care costs.^10,11

Women Veterans

CLBP appears to be even more prevalent among military veterans, where rates are estimated to be 30%–60% among Gulf War veterans.^12,13 Rates of CLBP among veterans tend to increase with longer follow-up periods and with more intensive levels of training and combat.^14,15 Women veterans make up an increasingly larger proportion of all veterans, and they have been shown to differ from men veterans in a number of ways. In the past few years, the proportion of veterans who are women has increased from 7.4% (2 million) to almost 10% (2.7 million).¹⁶ Fourteen percent (14%) of active duty forces and 20% of new military recruits are women. Research suggests that women veterans from recent military conflicts are more likely to seek care from Veterans Administration (VA) facilities,¹⁷ experience more pain,¹⁸ and have more depression and different mental health complaints than men veterans.¹⁹ To address the recent influx of women into the military and the special needs of the female veteran population, the VA Research and Development Women's Health program has developed a women's health research agenda in order to improve the health and health care of women veterans and position itself as a national leader in women's health research.¹⁶

Treatment of Chronic Low Back Pain

Most CLBP (85%) cannot be linked to specific physical abnormalities, and therefore, is considered nonspecific.²⁰ Treatment for nonspecific CLBP usually begins with medication management and self-care instruction.²¹ However, adherence to self-care exercises can be challenging, and the long-term use of pain medications has known disadvantages.^22,23 Thus, additional nonpharmacologic approaches are frequently added. Among the various nonpharmacologic approaches, none are considered highly efficacious or the treatment of choice. Research does indicate that complementary and alternative therapies such as acupuncture,^24,25 massage therapy,²⁶ and yoga produce sizeable therapeutic effects among persons with CLBP^{27

–34} and these therapies are now included in the Clinical Practice Guidelines of the American Pain Society.²³ Among these therapies, yoga may have the benefit of costing less per person treated because it can be easily administered in group format²³ and can be practiced at home. Other mind–body therapies delivered in groups such as t'ai chi and qi gong have shown promise with other pain conditions but are yet to be well-studied among people with CLBP.^35
–37

Yoga and Chronic Back Pain

An accumulating body of research indicates that yoga is beneficial for treating general musculoskeletal pain,³⁸ CLBP specifically^{27

–34} and mental health issues that are often associated with pain conditions.^39
–41 The two larger randomized, controlled studies have found that yoga can reduce pain and improve function in people with CLBP.^31,34 The pilot study by Williams et al. compared a group practicing Iyengar yoga to an educational control group and found significantly greater reductions in pain, functional disability, and pain medication usage for yoga participants. The study by Sherman et al. randomized 101 adults to one of the following: self-care literature, an exercise intervention, or Viniyoga-style yoga. At 12 weeks, the yoga group had better physical functioning than the other groups. At 26 weeks, the yoga group had fewer symptoms and better back-related function than the self-care book group.

The studies by Williams et al.³⁴ and Sherman et al.³¹ demonstrate that yoga therapy can provide significant benefits to persons with chronic back pain. However, these studies did not report data on mental health outcomes, and it was unknown whether similar effects would be found among persons receiving health care from the Veterans Affairs Healthcare System (VAHS). VAHS patients are more likely to have substance use and/or mental health problems and are predominantly male. To study the benefits of yoga for VAHS patients with CLBP, a clinical yoga program at the VA San Diego was evaluated. Despite limited statistical power, the published results of the pre–post design indicate that yoga participants had significant improvements in pain, depression, energy, and SF12-Mental Composite Score.²⁸ Home practice and yoga attendance were associated with greater improvements. Based on participation rates, the study also concluded that women may be more likely to perform yoga than men in the VA system.

Women are more likely than men to use mind–body therapies⁴² and comprised 76% of yoga practitioners in 2002.⁴³ In addition, musculoskeletal conditions were the leading health problem associated with yoga participation.⁴³ With the proportion of women veterans increasingly rapidly, and the VA prioritizing research on women's health, the purpose of the current study was to compare the impact of a yoga program between women and men with CLBP in the VA San Diego Healthcare System (VASDHS).

Materials and Methods

Study design

VA patients approved to attend a clinical yoga program at the VASDHS between 2005 and 2009 were invited to complete a packet of questionnaires before and after the yoga program. The study employed a pre–post design and was unfunded.

Clinical yoga program

The VASDHS began offering a yoga program for patients with CLBP in 2003. The program was started by a yoga-trained VA primary care physician. The ongoing program consists of weekly yoga sessions led by a certified yoga instructor and an assistant instructor. Primary care physicians refer VA patients with CLBP to the yoga program as part of clinical care. To ensure safe participation, each patient is screened by the yoga-trained physician before starting the class. The yoga-trained clinician evaluated patients for participation on the following dimensions with an interview and examination: a diagnosis of chronic benign low back pain of 6 months duration or longer, being followed by a VA primary care provider, and minimal use of narcotic medication for back pain (less than daily use over last 6 months) or a verbal desire to reduce any narcotic medication use. Other factors considered based on clinician judgment included the following: spinal fusion or inserted spinal hardware, difficulty understanding or carrying out instructions, morbid obesity, active substance use disorder, or other acute psychologic or medical problems that may interfere with regular yoga participation. Patients are encouraged to attend at least eight yoga sessions before deciding whether yoga is helpful. Patients are instructed to bring a yoga mat, wear loose-fitting clothing, and limit food intake for the 2-hour period prior to yoga.

Three (3) different yoga instructors with 4–7 years of instruction experience led the sessions between 2005 and 2009 and all were trained in Anusara yoga. Anusara yoga is a type of Hatha yoga that emphasizes postural alignment, coordination of movement and breath, and positive mental attitudes and cognitions. Anusara yoga is designed to benefit students of any level of experience or ability. The certified instructors demonstrated and led the students through a series of 32 yoga poses that were chosen specifically for patients with CLBP. Movement through the yoga poses was guided at a slow to moderate pace. Students are instructed to take slow, deep breaths in conjunction with various poses. At times, the yoga students are asked to focus their attention on the alignment of their body during the poses or are asked to visualize positive images, emotions, or thoughts. Because the yoga sessions could only be offered once per week, students were encouraged to practice yoga at home, but to stick to basic poses and put safety first.

Participants and research procedure

Patients who were screened and eligible for participation in the clinical yoga program between May 2005 and August 2009 were told about the yoga research study and were invited to participate. If interested was expressed, the screening physician contacted the yoga research staff and/or gave the patients contact information for the research staff. Research staff arranged to meet the interested patients 30 minutes before their first yoga class. The study was described and informed consent was provided. Patients completed a battery of questionnaires at baseline and 10 weeks later. Because the yoga sessions were cancelled on occasion, a 10-week follow-up period was chosen to ensure that participants had a chance to attend at least eight sessions as requested by the physician. The assessments took roughly 20–30 minutes to complete. The study was unfunded and patients did not receive compensation for completing the questionnaires. Consent was also obtained to access patient medical records for verification of medical diagnoses and attendance. Patients were assigned an identification number and de-identified data were entered into computers located on the VA secure data network. Protected health information was stored in locked file cabinets. Questionnaires were scored and data were analyzed using SPSS statistical software (SPSS Inc., Chicago, IL). Of the 71 participants who completed the baseline assessment, 18 did not complete the follow-up assessment. These patients could not be recontacted, or declined to complete the follow-up questionnaire.

Measures

The self-report assessment consisted of a sociodemographic questionnaire, measures of pain, depression, energy/fatigue, and health-related quality of life, and a one-page evaluation of the program.

Pain was measured using a modified version of the Medical Outcomes Study pain severity scale. This scale was changed to omit the skip pattern and add "physical discomfort" to the item stems.⁴⁴ This scale was further modified by substituting a 0–10 visual numeric scale for the original 0–20 numeric scale in items 1 and 2. The scales produces an “average,” “worst,” and total pain score that combines all responses. The scale has been used in a number of other studies of chronic illness.^45,46

Fatigue/Energy were measured using items adapted from the Medical Outcomes Study for use with chronic illness populations. The total score ranges from 0 to 5 and consists of the mean of the responses to five questions. The reliability and validity of the measures are well established.⁴⁷

Depression was assessed using the Center for Epidemiologic Studies Short Depression Scale (CESD-10).⁴⁸ The measure assesses mood symptoms using 10 items that are rated on a 4-point Likert scale ranging from 0 (Never) to 3 (All of the Time). The 10-item measure had high predictive accuracy for scores on full-length CES-D⁴⁹ and established reliability and validity.⁴⁸ Scores range from 0 to 30, and a score of 10 or greater is generally considered depressed.

Health-Related Quality of Life was measured using the Short-form 12 (SF12), which was derived from the longer SF-36.⁵⁰ The measure produces two subscale scores—the Physical Composite Score (PCS-12) and Mental Composite Score (MCS-12)—that when transformed, range from 0 to 100 with higher scores indicating better health-related quality of life. The SF12 subscales have psychometric properties similar to those of the 36-item measure.⁵¹

Attendance/home practice. Attendance of yoga sessions was tracked by the yoga instructors using a sign-in sheet and was entered into the VA medical record system by the instructors. As part of a one-page program evaluation, participants self-reported how often they practiced yoga at home. Home practice was assessed on a 5-point scale (Never=1, 1–3 times total=2, 1–2 times weekly=3, 3–4 times weekly=4, Almost every day=5).

Statistical analyses

Sociodemographic characteristics of male and female participants were compared using χ² and independent t-tests. Repeated-measure analyses of covariance (ANCOVAs) were used to compare pre- and post-test scores on measures of pain, energy/fatigue, depression, and quality of life by gender while controlling for differences measured at the baseline assessment. Covariates were retained in the analysis when p<0.05. Characteristics of participants who completed both assessments were compared to those of participants who did not complete the second assessment, using χ² and independent t-tests.

Results

The 53 participants who completed both assessments had a mean age of 53 years, and were well educated, 41% nonwhite, 49% married, 56% had commutes<30 minutes, and had varying employment status (Table 1).

Table 1.

Participant Demographics

Variable	Men (n=40)	Women (n=13)	p-Value
Mean age: mean (SD)	56.2 (14.1)	42.1 (12.4)	0.002^**
Education: n (%)			0.27–0.29
High school grad/GED	6	1
Some college	12	3
College graduate	10	7
Postgraduate	12	2
Ethnicity: n (%)			0.74–76
African-American	6	2
Asian/Pacific Islander	5	1
Hispanic	4	3
Non-Hispanic white	24	7
Other	1	0
Employment: n (%)			0.11–0.14
Unemployed	4	1
Disabled	7	4
Retired	12	2
Employed	16	3
Other	1	3
Marital status: n (%)			0.76–0.79
Married/partner	21	5
Widowed	1	0
Divorced or separated	11	5
Single	7	3
Travel time to VA: n (%)			0.31–0.39
0–30 minutes	23	7
30–60 minutes	13	5
60–90 minutes	1	0
90+ minutes	3	1
Homeless in last 5 years			0.56
Yes	4	0
No	36	13

SD, standard deviation; GED, general equivalency diploma; VA, Veterans Affairs. ^**, p<.05.

Comparison of male and female participants on sociodemographic variables and medical diagnoses measured at baseline revealed that male participants were significantly older, and a significantly higher proportion of men had a diagnosis of hypertension (Table 2). Because of the small and unbalanced sample size, differences in baseline variables between males and females that were not significant at 0.05 were examined. Differences between males and females on education and employment appeared meaningful. Age, education, employment, and diagnoses of hypertension and depression were examined as covariates in ANCOVA analyses of outcomes variables between men and women. Male participants were three times as likely to have a diagnosis of depression listed in their medical record, yet they had lower scores on the CES-D as baseline.

Table 2.

Participant Comorbidities

Comorbidity and ICD-9	Men (n=40) (%)	Women (n=13) (%)	p-Value
Low back pain (724.2)	85	77	0.51
Hypertension (401.9)	45	7.7	0.01^*
Arthritis (715.9, V13.4, V17.7, 714.0)	25	15	0.48
Diabetes mellitus (250.0, 648.0)	13	8	0.64
Anemia (285.9)	3	8	0.40
Cataract (366.9/366.1)	3	0	0.57
Cancer (199.1)	0	0	–
Urinary tract infection (599.0, V13.02)	0	0
Chronic obstructive pulmonary disease (COPD)/asthma (490–496, 493.9,V17.5)	0	0	–
No. of comorbid physical disorders (mean)	1.7	1.2	0.04^*
Depression (296.2, 296.3, 300.4, 311)	45	15	0.06
Post-traumatic stress disorder (PTSD) (309.81)	30	15	0.31
Anxiety (300.0, 300.2)	15	23	0.51
Bipolar disorder (296.0-1, 296.4-5, 296.7-9)	8	8	0.98
Alcohol dependence (303, 305.0)	8	0	0.32
Drug dependence (various)	8	0	0.32
Schizophrenia (295)	3	0	0.57
No. of comorbid psychologic disorders (mean)	1.2	0.6	0.13

ICD, International Classification of Diseases.

^*, p<.05.

Analyses indicate that female participants had significantly greater improvements than male participants on depression, pain “on average,” energy, and SF12–mental health (Table 3). No differences were found between men and women for pain “at its worst,” total pain score, or SF12–physical health.

Table 3.

Participant Outcome Scores

Measure	Baseline	Follow-up	Change	p-Value
CES-D				0.046^*
Males	12.9	11.8	−1.1
Females	15.2	10.1	−5.1
Total sample	14.0	10.9	−3.1	0.003^*
Pain–average (cv=education)				0.050^*
Males	5.3	4.7	−0.6
Females	5.8	4.4	−1.4
Total sample	5.5	4.5	−1.0	0.002^*
Pain–worst				0.839
Males	7.3	6.6	−0.1
Females	7.2	6.4	−0.2
Total sample	7.2	6.5	−0.7	0.035
Pain–total				0.164
Males	71.1	62.8	−8.3
Females	75.0	60.0	−15.0
Total sample	73.0	61.4	−11.6	<0.001^*
Energy/fatigue				0.011^*
Males	2.3	2.6	.3
Females	1.8	3.0	1.2
Total sample	2.0	2.8	0.8	<0.001^*
HRQOL–SF 12: MCS (cv=age)				0.044
Males	41.9	42.5	0.6
Females	39.5	48.6	9.1
Total sample	40.7	45.6	4.9	0.009^*
HRQOL–SF 12: PCS				0.620
Males	37.2	36.6	−0.6
Females	36.0	37.1	1.1
Total sample	36.6	36.9	0.3	0.858

CES-D, Center for Epidemiologic Studies Depression Scale; cv, co-variate; HRQOL, health-related quality of life; SF12, Short-form 12; MCS, Mental Composite Score; PCS, Physical Composite Score. ^*, p<.05.

We examined whether attendance at yoga sessions or self-reported home practice differed by gender, and subsequently, might explain the differential improvement on outcome variables for men and women. As shown in Table 4, men attended more yoga sessions than women and reported slightly less home practice, but neither difference was significant.

Table 4.

Yoga Attendance and Home Practice

Yoga participation	Men Mean (SD) or n (%)	Women Mean (SD) or n (%)	p-Value
Actual attendance	5.7 (3.3)	5.1 (3.5)	0.55
Reported home practice
Never	7	3	0.75–0.77
1–3 times	15	2
1–2 times weekly	8	3
3–4 times weekly	7	2
Every day	2	1

SD, standard deviation.

Since only 53 of 71 participants who enrolled in the study completed the follow-up assessment, a brief check was done of whether participants who completed both assessments differed from noncompleters on gender, program attendance, and outcome variables at baseline. No differences were found between participants who did and did not complete the second assessment, as determined by gender, depression, energy, pain, or SF12–mental health component scores. Noncompleters of the second assessment attended fewer yoga classes (t(69)=−1.98, p=0.051) and had significantly lower SF12–physical component scores (t(66)=−2.13, p=0.037).

Discussion

CLBP is a highly prevalent health problem in the United States and military veterans are even more likely to experience CLBP. Although more acute and immediate health problems such as post-traumatic stress disorder and traumatic blast injury gain more attention among veterans returning from duty, CLBP and other emerging chronic conditions should not be overlooked. In its untreated course, CLBP often results in negative psychologic symptoms,^3

–6 reduced health-related quality of life,^8,9 increased functional disability,⁷ and increased health care costs^10,11 in addition the pain itself.

The VASDHS has been offering yoga as an alternative therapy for veterans with CLBP since 2003, and beneficial health outcomes have been described previously.²⁸ The current study explored whether men and women veterans participating in the VA San Diego yoga program for CLBP differed in their attendance, home practice, or responsiveness to the intervention. After controlling for baseline differences on sociodemographics and comorbid disorders, it was found that women had greater improvements than men on measures of depression, pain (“on average”) ratings, energy, and the SF12 mental health scale. These differences emerged despite very little difference between men and women on yoga attendance or home practice of yoga.

The men and women veterans participating in the yoga program were fairly different in a number of ways. The mean age of the men was 14 years older than that of the women, and men were more likely to have comorbid disorders. Although the differences between men and women remained after controlling for these differences, it is possible that the groups differed on other characteristics that were not measured. It is possible that unmeasured differences could explain some of the significant differences in health outcomes that were identified.

Although other studies have reported that women are more frequent users of yoga⁵² and alternative therapies in general,^53
–55 no other evidence was found that women respond differently or benefit more from the same yoga or other mind–body intervention. It is possible that as a result of the greater interest in alternative therapies expressed by women, they have a greater positive expectation about yoga interventions. However, this is speculative and more research would be needed on such differences and expectations to answer this question.

The current results are important since the number of women veterans is growing rapidly, and women who had recent military service appear more likely to use VA health care services.¹⁷ There is evidence that women in the military experience pain differently¹⁸ and have different mental health care needs.¹⁹ These findings underscore the importance of studying women's health in the VA, and this study's results contribute to this effort.

Limitations

Limitations of this study include the single-group pre–post design, a small sample size, and some attrition from the follow-up assessment. Although it was established that attendance and home practice of yoga were well correlated with improved outcomes, the lack of a random assignment and a comparison group prevents us from concluding that the effects did not result from unmeasured factors.

The project was unfunded, which contributed to the small sample size and greater attrition. However, despite the small sample size, especially for women, significant differences were found. Participants were not compensated for completing the assessment, and it was found that participants who did not complete the follow-up assessment attended yoga less and had greater physical comorbidity. However, the proportion of assessment completers and noncompleters that were men and women were not significantly different. Thus, this is not a direct threat to the study's tentative conclusion that women appeared to benefit from the yoga therapy more than men.

This study also had a limited number of female participants, which could have a small effect on statistical results. On average, women make up only about 10% or less of the veteran population. There were complete data available for 13 women, or 23% of participants, which is much higher than the reported number of female veterans seen at the VA, but still low overall.

Conclusions

In this sample, it was found that women were more likely to participate in a clinical yoga program for CLBP and were more likely to benefit from the yoga sessions. The proportion of veterans who are women is increasing, and our findings further the goal of tailoring health care programs to the unique needs of women veterans. A larger, more definitive study of yoga in the VA system is needed to establish the health benefits of yoga for CLBP and to explore whether men and women differ in their response to yoga.

Footnotes

Acknowledgments

This project was unfunded.

Disclosure Statement

The authors do not have any conflictual arrangements or commercial associations to disclose in association with this study.

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