ABSTRACT

Objective. To evaluate sex differences in the prevalence of overall pain, moderate-severe pain, and persistent pain among Veterans of Operations Enduring Freedom and Iraqi Freedom seen at VA outpatient clinics, and to evaluate sex differences in pain assessment.

Design. The observational cohort consisted of Veterans discharged from the U.S. military from October 1, 2001 to November 30, 2007 that enrolled for Veterans Administration (VA) services or received VA care before January 1, 2008. We limited the sample to the 153,212 Veterans (18,481 female, 134,731 male) who had 1 year of observation after their last deployment.

Results. Pain was assessed in 59.7% (n = 91,414) of Veterans in this sample. Among those assessed, 43.3% (n = 39,591) reported any pain, 63.2% (n = 25,028) of whom reported moderate-severe pain. Over 20% (n = 3,427) of Veterans with repeated pain measures reported persistent pain. We found no significant difference in the probability of pain assessment by sex (RR = 0.98, 95% CI 0.96, 1.00). Female Veterans were less likely to report any pain (RR 0.89, 95% CI 0.86, 0.92). Among those with any pain, female Veterans were more likely to report moderate–severe pain (RR 1.05, 95% CI 1.01, 1.09) and less likely to report persistent pain (RR 0.90, 95% CI 0.81, 0.99).

Conclusions. As the VA plans care for the increasing numbers of female Veterans returning from Iraq and Afghanistan, a better understanding of the prevalence of pain, as well as sex-specific variations in the experience and treatment of pain, is important for policy makers and providers who seek to improve identification and management of diverse pain disorders.

Introduction

Pain is frequently reported by Veterans returning from war [1]. Among Veterans of recent conflicts, including Operations Desert Shield/Desert Storm, as well as Operation Enduring Freedom/Operation Iraqi Freedom (OEF/OIF), several painful conditions are highly prevalent [2–4]. Although studies in civilian populations have reported a higher prevalence of many pain syndromes among women compared with men [5–10], sex differences in the prevalence and characteristics of pain in Veterans returning from OEF/OIF have not yet been investigated.

In civilian populations, women more commonly report specific pain syndromes including migraine headaches [11], oral-facial pain [12], fibromyalgia [13], and abdominal pain [14]. Women also report more severe and longer lasting pain than men [15–17]. In some experimental human and animal models [18–20] females experience higher pain severity at lower thresholds and have less tolerance to noxious stimuli than males, but other studies have not consistently supported these findings [20]. Few studies have addressed gender differences in pain among Veterans. A preliminary study of pain in women Veteran primary care patients [21] found a higher prevalence of pain compared with a similar study in male Veteran primary care patients [22]. Another study of gender differences in health related quality of life found that, among Veterans with mental illness, women reported more pain than men [23].

The proportion of women in active military service (currently 15%) is increasing and is expected to double in the next 5 years [24]. Female Veterans of OEF/OIF are using VA services more frequently than any previous female cohort [25]. These new female Veterans are younger, more likely to identify as belonging to a racial minority, and are less likely to be married than their male counterparts [26]. They have a high prevalence of mental health disorders [27], higher rates of exposure to combat trauma than previous cohorts of women Veterans, and may have high rates of exposure to sexual trauma. These factors place them at risk for chronic pain syndromes [28,29].

Routine pain assessment has become part of health screening at the VA [30] but previous studies have not addressed whether pain screening varies by sex. No studies have reported whether women returning from war have more severe or persistent pain than their male counterparts. An understanding of the epidemiology of pain in the growing population of female Veterans will be essential as the VA plans pain treatment services.

We hypothesized that female OEF-OIF Veterans would have more overall pain, more moderate–severe pain, and more persistent pain than their male counterparts. We designed this study to evaluate sex differences in the prevalence, severity, and persistence of pain among OEF/OIF Veterans seen at VA outpatient clinic visits during the year after returning from deployment. We also evaluated whether the probability of pain assessment at outpatient visits differed by sex, and whether any association differed by the presence of post-traumatic stress disorder (PTSD) or depression.

Methods

Study Population

The population consisted of the list of Veterans obtained from VA's OEF/OIF roster provided by Defense Manpower Data Center—Contingency Tracking System Deployment File. The roster contains information on all personnel discharged from the U.S. military from October 1, 2001 to November 30, 2007 who enrolled for VA services or received VA care before January 1, 2008 (N = 406,802). Because we were interested in pain assessment, we limited our sample to Veterans who had at least one visit to a VA clinic most likely to obtain pain scores (primary care, women's clinics, and medical or surgical subspecialty clinics). We limited the sample to Veterans who had 1 year of observation after their last deployment end date in order to standardize the time between potential exposures and pain measurement. The analytic sample thus included 153,212 Veterans.

Data Sources

The VA OEF/OIF roster includes information on sex, date of birth, race, education, marital status, military rank, branch of service (e.g., Army, Marine Corps), and deployment start and end dates. Information on eligible visits, ICD-9 codes used to determine medical and psychiatric conditions, and pain scores was ascertained from the VA Corporate Data Warehouse.

The pain numeric rating score is recorded along with vital signs according to VA's “pain as a fifth vital sign” campaign [30]. At each relevant visit, Veterans were asked to rate the intensity of their current pain on a scale of 0–10, where 0 is no pain and 10 is the worst possible pain. We retained only scores recorded at an outpatient visit. A missing or invalid score was considered as not assessed (<1% responses). When multiple scores were recorded on one day, we retained only the highest score.

We defined pain assessment as having any valid pain score in the 1-year observation period. Then, using the first valid pain score in the observation period, we defined any pain as a score ≥1. Consensus on the optimal numeric rating score cutoff for moderate–severe pain is lacking, but most studies use either 4 or 5 [31,32]. We defined moderate–severe pain as a score ≥4 because this is most consistent with VA clinical practice and policy [33]. We had no direct measure of pain duration, so we defined persistent pain as three or more pain scores ≥4 recorded in at least three different months. This is consistent with common definitions of chronic pain that require at least 3–6 months duration.

ICD-9 codes from outpatient visits were then mapped to validated diagnostic groupings in order to determine the prevalence of PTSD and depression [34]. A Veteran was considered to have PTSD or depression if codes occurred on two or more outpatient visits. This methodology has been used in the identification of psychiatric disorders in administrative data [35] and in identification of HIV in Medicaid data [36].

Statistical Analysis

Chi-square tests were used to examine bivariate relationships between categorical variables and t-tests or nonparametric tests, as appropriate, were used for continuous variables. Because our study is a cohort study and the primary outcomes were common events, we used Poisson regression with a log link and robust variance estimates to calculate relative risks (RR) and 95% confidence intervals (CI). To control for potential confounding that could distort the risk estimates, all demographic variables that were significant in bivariate analyses were entered into the model as covariates. PTSD and depression diagnoses were not entered into the multivariable model given that the diagnoses may have occurred after the pain assessment.

Results

The sample consisted of 18,481 female and 134,731 male Veterans with at least one eligible visit in the year after their last deployment (Table 1). Compared with males, female Veterans were younger (mean age 30.2 vs 32.6 P < 0.0001); more likely to be Black (30.3% vs 14.2% P < 0.0001); more likely to have a college education (28.7% vs 24.0%, P < 0.0001); less likely to be married (31.8% vs 50.1%, P < 0.0001); more likely to be officers (8.0% vs 7.0 %, P < 0.0001); and less likely to serve in the Marine Corps (2.9% vs 11.2%, P < 0.0001). PTSD was less frequently diagnosed in female Veterans (9.9% vs 11.3%, P < 0.0001); in contrast, depression was more common (12.2% vs 7.5%, P < 0.0001). Female Veterans also had a higher mean number of clinic visits (4.7 vs 4.1, P < 0.0001).

Table 1

Demographics, pain assessment, pain characteristics, by sex in OEF/OIF Veterans utilizing VA clinics in first year after end of deployment

 Female n = 18,481 Male n = 134,731 P value 
Age mean (SD) 30.2 (8.8) 32.6 (9.8) <0.0001 
Race   <0.0001 
  Black 30.3% 14.2% 
  Hispanic 10.8% 11.8% 
  White 52.9% 68.8% 
  Other 3.3% 2.6% 
  Unknown 2.7% 2.5% 
Education   <0.0001 
  Less than high school 1.4% 1.5% 
  High School 69.9% 74.6% 
  College 28.7% 24.0% 
Marital status   <0.0001 
  Married 31.8% 50.1% 
  Never married 57.9% 44.5% 
  Divorced/other 10.3% 5.4% 
Rank   <0.0001 
  Enlisted 91.4% 91.8% 
  Officer 8.0% 7.0% 
  Warrant officer 0.6% 1.2% 
Branch   <0.0001 
  Army 78.9% 76.1% 
  Air Force 10.3% 6.6% 
  Marine Corps 2.9% 11.2% 
  Navy 7.8% 6.1% 
  PTSD diagnosis 9.9% 11.3% <0.0001 
  Any depression diagnosis 12.2% 7.5% <0.0001 
Clinic visits* mean (SD) 4.7 (5.8) 4.1 (5.4) <0.0001 
Pain assessment 60.1% 59.6%  0.247 
Pain score for those with any pain mean (SD) 4.8 (2.7) 4.5 (2.7) <0.0001 
Any pain 38.1% 44.0% <0.0001 
Moderate pain 68.0% 62.6% <0.0001 
Persistent pain 18.0% 21.2% <0.0001 
 Female n = 18,481 Male n = 134,731 P value 
Age mean (SD) 30.2 (8.8) 32.6 (9.8) <0.0001 
Race   <0.0001 
  Black 30.3% 14.2% 
  Hispanic 10.8% 11.8% 
  White 52.9% 68.8% 
  Other 3.3% 2.6% 
  Unknown 2.7% 2.5% 
Education   <0.0001 
  Less than high school 1.4% 1.5% 
  High School 69.9% 74.6% 
  College 28.7% 24.0% 
Marital status   <0.0001 
  Married 31.8% 50.1% 
  Never married 57.9% 44.5% 
  Divorced/other 10.3% 5.4% 
Rank   <0.0001 
  Enlisted 91.4% 91.8% 
  Officer 8.0% 7.0% 
  Warrant officer 0.6% 1.2% 
Branch   <0.0001 
  Army 78.9% 76.1% 
  Air Force 10.3% 6.6% 
  Marine Corps 2.9% 11.2% 
  Navy 7.8% 6.1% 
  PTSD diagnosis 9.9% 11.3% <0.0001 
  Any depression diagnosis 12.2% 7.5% <0.0001 
Clinic visits* mean (SD) 4.7 (5.8) 4.1 (5.4) <0.0001 
Pain assessment 60.1% 59.6%  0.247 
Pain score for those with any pain mean (SD) 4.8 (2.7) 4.5 (2.7) <0.0001 
Any pain 38.1% 44.0% <0.0001 
Moderate pain 68.0% 62.6% <0.0001 
Persistent pain 18.0% 21.2% <0.0001 
*

Clinic visits include general medical, primary care, and women's clinics.

Defined as pain score ≥4, assessed only among those with any pain score ≥1.

Defined as ≥3 pain scores ≥4 in three different months, assessed among those with any pain score ≥1 and at least 3 available pain scores.

SD = standard deviation; PTSD = post-traumatic stress disorder.

Pain was assessed in 59.7% (n = 91,414) of Veterans in this sample. Among those assessed, 43.3% (n = 39,591) reported any pain. Among those reporting any pain, 63.2% (n = 25,028) reported moderate-severe pain. Of the 16,611 Veterans with at least three pain scores in three separate months, 20.6% (n = 3,427) met our definition of persistent pain (Figure 1).

Figure 1

Flow diagram of pain assessment, moderate-severe pain, and persistent pain among Veterans of Operations Enduring Freedom and Iraqi Freedom (OEF/OIF) seen at VA outpatient clinics.

Figure 1

Flow diagram of pain assessment, moderate-severe pain, and persistent pain among Veterans of Operations Enduring Freedom and Iraqi Freedom (OEF/OIF) seen at VA outpatient clinics.

In bivariate analysis, there was no significant difference in the probability of pain assessment by sex (59.6% vs 60.1%, P = 0.24). Female Veterans were significantly less likely to report any pain (38.1% vs 44.0%, P < 0001). Among Veterans with any pain, female Veterans were more likely to report moderate–severe pain (68.0% vs 62.6%, P < 0.0001) and less likely to report having persistent pain (18.0% vs 21.2%, P < 0.001).

Results were similar after adjusting for potentially confounding characteristics in multivariable analyses (Table 2). We found no significant difference in the probability of pain assessment by sex (RR = 0.98, 95% CI 0.96, 1.00). Female Veterans were less likely to report any pain (RR 0.89, 95% CI 0.86, 0.92). Among those with any pain, female Veterans were more likely to report moderate–severe pain (RR 1.05, 95% CI 1.01, 1.09) and less likely to have persistent pain (RR 0.90, 95% CI 0.81, 0.99) than male Veterans. Estimates for the full set of covariates are shown in Table 2.

Table 2

Results of Poisson regression models assessing the relative risk for pain assessment, any pain, moderate pain, and persistent pain

Variable Relative risk (95%CI)
 
Assessed Any pain Moderate pain Persistent pain 
Female 0.98 (0.96, 1.00) 0.89 (0.86, 0.92) 1.05 (1.01, 1.09) 0.90 (0.81, 0.99) 
Male Ref. Ref. Ref. Ref. 
Age 1.00 (1.00, 1.00) 1.00 (1.00, 1.00) 1.00 (1.00, 1.00) 1.00 (1.00, 1.01) 
Divorced/separated 1.05 (1.02, 1.08) 1.00 (0.96, 1.04) 1.00 (0.95, 1.06) 0.99 (0.87, 1.12) 
Never married 1.10 (1.08, 1.12) 0.88 (0.86, 0.90) 0.98 (0.95, 1.01) 0.80 (0.73, 0.87) 
Married Ref. Ref. Ref. Ref. 
Black 1.00 (0.98, 1.02) 0.97 (0.94, 1.00) 1.22 (1.18, 1.26) 1.10 (1.01, 1.20) 
Hispanic 1.07 (1.05, 1.10) 0.92 (0.90, 0.95) 1.01 (0.97, 1.05) 0.68 (0.61, 0.76) 
Other 1.05 (1.01, 1.09) 0.97 (0.91, 1.03) 1.09 (1.01, 1.17) 0.70 (0.56, 0.89) 
Unknown 0.92 (0.88, 0.96) 0.97 (0.90, 1.03) 1.16 (1.07, 1.25) 1.17 (0.93, 1.46) 
White Ref. Ref. Ref. Ref. 
College 1.03 (1.02, 1.05) 0.92 (0.90, 0.95) 0.90 (0.87, 0.93) 0.75 (0.68, 0.82) 
Less than high school 1.05 (0.99, 1.10) 0.98 (0.91, 1.07) 1.02 (0.93, 1.13) 0.89 (0.67, 1.17) 
High school graduate Ref. Ref. Ref. Ref. 
Officer 0.84 (0.82, 0.87) 0.88 (0.83, 0.92) 0.86 (0.80, 0.92) 0.78 (0.64, 0.95) 
Warrant 0.81 (0.76, 0.87) 0.89 (0.80, 0.99) 0.90 (0.78, 1.04) 0.73 (0.50, 1.07) 
Enlisted Ref. Ref. Ref. Ref. 
Air Force 0.70 (0.68, 0.73) 0.92 (0.88, 0.97) 0.99 (0.93, 1.05) 0.86 (0.71, 1.05) 
Marine Corps 0.90 (0.88, 0.92) 1.02 (0.99, 1.06) 1.01 (0.97, 1.06) 0.96 (0.83, 1.11) 
Navy 0.91 (0.88, 0.93) 0.94 (0.90, 0.98) 0.97 (0.92, 1.03) 0.95 (0.81, 1.11) 
Army Ref. Ref. Ref. Ref. 
Visits 1.01 (1.01, 1.01) 1.02 (1.02, 1.02) 1.01 (1.00, 1.01) 1.03 (1.02, 1.03) 
Variable Relative risk (95%CI)
 
Assessed Any pain Moderate pain Persistent pain 
Female 0.98 (0.96, 1.00) 0.89 (0.86, 0.92) 1.05 (1.01, 1.09) 0.90 (0.81, 0.99) 
Male Ref. Ref. Ref. Ref. 
Age 1.00 (1.00, 1.00) 1.00 (1.00, 1.00) 1.00 (1.00, 1.00) 1.00 (1.00, 1.01) 
Divorced/separated 1.05 (1.02, 1.08) 1.00 (0.96, 1.04) 1.00 (0.95, 1.06) 0.99 (0.87, 1.12) 
Never married 1.10 (1.08, 1.12) 0.88 (0.86, 0.90) 0.98 (0.95, 1.01) 0.80 (0.73, 0.87) 
Married Ref. Ref. Ref. Ref. 
Black 1.00 (0.98, 1.02) 0.97 (0.94, 1.00) 1.22 (1.18, 1.26) 1.10 (1.01, 1.20) 
Hispanic 1.07 (1.05, 1.10) 0.92 (0.90, 0.95) 1.01 (0.97, 1.05) 0.68 (0.61, 0.76) 
Other 1.05 (1.01, 1.09) 0.97 (0.91, 1.03) 1.09 (1.01, 1.17) 0.70 (0.56, 0.89) 
Unknown 0.92 (0.88, 0.96) 0.97 (0.90, 1.03) 1.16 (1.07, 1.25) 1.17 (0.93, 1.46) 
White Ref. Ref. Ref. Ref. 
College 1.03 (1.02, 1.05) 0.92 (0.90, 0.95) 0.90 (0.87, 0.93) 0.75 (0.68, 0.82) 
Less than high school 1.05 (0.99, 1.10) 0.98 (0.91, 1.07) 1.02 (0.93, 1.13) 0.89 (0.67, 1.17) 
High school graduate Ref. Ref. Ref. Ref. 
Officer 0.84 (0.82, 0.87) 0.88 (0.83, 0.92) 0.86 (0.80, 0.92) 0.78 (0.64, 0.95) 
Warrant 0.81 (0.76, 0.87) 0.89 (0.80, 0.99) 0.90 (0.78, 1.04) 0.73 (0.50, 1.07) 
Enlisted Ref. Ref. Ref. Ref. 
Air Force 0.70 (0.68, 0.73) 0.92 (0.88, 0.97) 0.99 (0.93, 1.05) 0.86 (0.71, 1.05) 
Marine Corps 0.90 (0.88, 0.92) 1.02 (0.99, 1.06) 1.01 (0.97, 1.06) 0.96 (0.83, 1.11) 
Navy 0.91 (0.88, 0.93) 0.94 (0.90, 0.98) 0.97 (0.92, 1.03) 0.95 (0.81, 1.11) 
Army Ref. Ref. Ref. Ref. 
Visits 1.01 (1.01, 1.01) 1.02 (1.02, 1.02) 1.01 (1.00, 1.01) 1.03 (1.02, 1.03) 

95% CI = 95% confidence interval; Ref. = reference group.

When stratified by depression or PTSD diagnosis, Veterans with depression or PTSD were more likely to be assessed for pain (P < 0.0001); however, there was no significant difference in the proportion of Veterans assessed for pain by sex in those with PTSD and depression (P > 0.05 in both cases) (Table 3).

Table 3

Homogeneity of odds for assessment, by PTSD and depression diagnoses

Diagnosis  Male Female P 
PTSD No 57.9% 58.8% 0.16 
Yes 72.9% 72.0% 
Depression No 41.6% 41.6% 0.08 
Yes 74.2% 72.3% 
Diagnosis  Male Female P 
PTSD No 57.9% 58.8% 0.16 
Yes 72.9% 72.0% 
Depression No 41.6% 41.6% 0.08 
Yes 74.2% 72.3% 

PTSD = post-traumatic stress disorder.

Discussion

To our knowledge, this is the first study of the sex-specific prevalence of pain in OEF-OIF Veterans. We used pain scores from VA outpatient clinic visits to estimate pain prevalence in Veterans returning from the OEF/OIF conflicts. Importantly, our results documented a lower prevalence of pain in women compared with men in the first year post-deployment even after adjusting for other demographic and clinical factors. In this sub-population of Veterans with pain, we found that women were slightly more likely than men to have moderate–severe pain; however, women had a lower prevalence of moderate–severe pain overall than men. Persistent pain was also less common among women than among men.

The lower prevalence of pain in women Veterans is an unexpected finding that is contrary to studies conducted in civilian populations. Several hypotheses may be pertinent to pain in Veterans of OEF/OIF. First, the relatively low prevalence of pain in returning female soldiers compared with male soldiers may reflect differences in exposure to combat trauma and injury. While women are excluded from serving in direct combat, they do work in a variety of support positions and may come under direct fire, so the true risk of injury for female Veterans is difficult to assess.

If one assumes an equal burden of risk for injury, two other potential hypotheses can be proposed. The high intensity and persistent level of threat in OEF/OIF may act as an equalizer of risk for stress-associated conditions, including pain, so that risk is more strongly related to the intensity and frequency of combat experience than to gender [37]. In addition, a “healthy warrior effect” (the disproportionate loss of psychologically unfit personnel early in training) [38] might even the playing field for deployed men and women, putting them at similar risk for pain syndromes.

The surprisingly lower rates of pain among women Veterans might also be a result of their reluctance to seek VA treatment due to either their gender or their higher likelihood of mental health disorders, especially depression. Women Veterans report more barriers to VA care and have used the VA less often than male Veterans in past eras [39–44]. Previous studies have also found that Veterans with mental health disorders are more likely to report barriers to seeking VA treatment [45], and mental health disorders, especially depression and PTSD [46], are often associated with chronic pain.

Our study has several limitations. Primarily, the accuracy of the pain numeric rating scale score as a screening test for pain has been questioned. Two studies that compared pain scores collected in routine clinical practice to the Brief Pain Inventory, a validated instrument that includes an assessment of pain related functional impairment, found that the pain score had only a modest accuracy for identifying patients with clinically important pain. In the first study, the pain numeric rating scale score missed nearly a third of patients with clinically important pain, and in the second study, pain numeric rating scale scores underestimated pain in 33% of cases and overestimated it in 12% [47,48]. This suggests that our estimates of pain prevalence based on pain scores may underestimate the true prevalence of pain in the OEF/OIF population; however, there is no evidence that misestimation would differ by sex. In addition, our analysis was limited to patients seen in clinics most likely to administer a pain score and thus, we are unable to evaluate OEF/OIF Veterans seen in other clinics or those not seeking VA care.

In conclusion, among OEF/OIF Veterans seen in VA outpatient clinics within 1 year of their last deployment, we found that women had a lower prevalence of overall pain, moderate-severe pain, and persistent pain then men. Examining whether sex differences in pain persist, increase or decrease over time is an important next step in VA pain research, and will help guide planning, resource allocation, and policy for women Veterans and OEF/OIF Veterans of both sexes.

Acknowledgments

Financial support: VA grants DHI 07-065-1 (Brandt PI, Haskell, Skanderson); VA HSR&D Research Enhancement Award Program (REAP) PRIME Project (Kerns PI; Goulet); CD207215-2 (Krebs PI).

References

1
Hyams
KD
Wignall
FS
Roswell
R
.
War syndromes and their evaluations: From the U.S. civil War to the Persian Gulf War
.
Ann Int Med
 
1996
;
125
(
5
):
398
405
.
2
Kroenke
K
Koslowe
P
Roy
M
.
Symptoms in 18,495 Persian Gulf War veterans. Latency of onset and lack of association with self-reported exposures
.
J Occup Environ Med
 
1998
;
40
:
520
8
.
3
Gironda
RJ
Clark
ME
Massengale
JP
Walker
RL
.
Pain among veterans of operations enduring freedom and iraqi freedom
.
Pain Med
 
2006
;
7
(
4
):
339
43
.
4
Kang
HK
Mahan
CM
Lee
KY
et al
Illnesses among United States veterans of the Gulf War: A population based survey of 30,000 veterans
.
J Occup Environ Med
 
2000
;
42
:
491
501
.
5
Magni
G
Marchetti
M
Moreschi
C
Merskey
H
Luchini
SR
.
Chronic musculoskeletal pain and depressive symptoms in the National Health and Nutrition Examination 1: Epidemiological follow-up study
.
Pain
 
1993
;
53
:
163
8
.
6
Anderson
HI
Ejlertsson
G
Leden
I
Rosenberg
C
.
Chronic pain in a geographically defined general population: Studies of differences in age, gender, social class and pain localization
.
Clin J Pain
 
1993
;
9
:
174
82
.
7
Von Korff
M
Dworkin
SF
LeResche
L
Kruger
A
.
An epidemiologic comparison of pain complaints
.
Pain
 
1988
;
32
:
173
83
.
8
LeResche
I
Von Korff
M
.
Epidemiology of chronic pain
. In:
Block
AR
.
Kremer
EF
Fernandez
E
, eds.
Handbook of Pain Syndromes: Biophyschosocial Perspectives
 .
Mahwah, NJ
:
Lawrence Erlbaum Associates Inc
.;
1999
.
9
Munche
SEP
Stewart
DE
.
Gender differences in depression and chronic pain conditions in a national epidemiologic survey
.
Psychosomatics
 
2007
;
48
(
5
):
394
9
.
10
Tsang
A
Von Korff
M
Lee
S
et al
Common chronic pain conditions in developed and developing countries: Gender and age differences and comorbidity with depression-anxiety disorders
.
J Pain
 
2008
;
9
(
10
):
883
91
.
11
Lipton
RB
Bigal
ME
.
The epidemiology of migraine
.
Am J Med
 
2005
;
118
(
suppl 1
):
S3
10
.
12
Oikarinen
RK
Jarvelin
MR
Baustia
AM
.
Facial pain and temporomandibular disorders: An epidemiological study of the Northern Finland 1966 birth cohort
.
Cranio
 
2000
;
18
(
1
):
40
6
.
13
Arendt
EA
.
Gender differences in musculoskeletal health
.
J Gend Specific Med
 
2000
;
3
(
7
):
58
64
.
14
Sandler
RS
Stewart
WF
Liberman
JN
Ricci
JA
Zorich
NL
.
Abdominal pain, bloating, and diarrhea in the United States: Prevalence and impact
.
Dig Dis Sci
 
2000
;
4596
:
1166
71
.
15
Cepeda
MS
Car
DB
.
Women experience more pain and require more morphine than men to achieve a similar degree of analgesia
.
Anesth Analg
 
2003
;
97
(
5
):
1464
8
.
16
Reisbord
LS
Greenland
S
.
Factors associated with self-reported back pain prevalence: A population based study
.
J Chron Dis
 
1985
;
38
:
691
702
.
17
Crook
J
Rideout
E
Browne
G
.
The prevalence of pain complaints in a general population
.
Pain
 
1984
;
18
:
299
314
.
18
Barrett
AC
Smith
ES
Picker
MJ
.
Sex-related differences in mechanical nociceptoin and antinociception produced by mu and kappa-opioid receptor agonist in rats
.
Eur J Pharmacol
 
2002
;
452
:
163
73
.
19
Bourquin
AF
Suveges
M
Pertin
M
et al
Assessment and analysis of mechanical allodynia-like behavior induced by spared nerve injury in the mouse
.
Pain
 
2006
;
122
:
14.e1
14
.
20
Riley
JL
Robinson
ME
Wise
EA
Myers
CD
Fillingim
RB
.
Sex differences in the perception of noxious experimental stimuli: A meta-analysis
.
Pain
 
1998
;
74
:
181
7
.
21
Haskell
SG
Heapy
A
Reid
MC
Papas
RK
Kerns
RD
.
The prevalence and age-related characteristics of pain in a sample of women veterans receiving primary care
.
J Womens Health (Larchmont)
 
2006
;
15
(
7
):
862
9
.
22
Kerns
RD
Otis
J
Rosenberg
R
Reid
MC
.
Veterans' reports of pain and associations with ratings of health risk behaviors; affective distress and use of the healthcare system
.
J Rehabil Res Dev
 
2003
;
40
(
5
):
371
9
.
23
Teh
CF
Kilbourne
AM
McCarthy
JF
Welsh
D
Blow
FC
.
Gender differences in health-related quality of life for veterans with serious mental illness
.
Psychiatr Serv
 
2008
;
59
(
6
):
663
9
.
24
Yano
E
.
What does women's health care look like in the veterans health administration? Results of a National Organizational Survey
 . Presented at Academy Health Annual Research Meeting; June 10, 2008.
25
Hayes
P
.
Women's health: Provision of quality care
 . Presented at VA Primary Care National Meeting, Summer,
2008
.
26
Office of the Actuary, Veterans Administration
.
Women Veterans: Past, Present and Future
 .
Washington, DC
:
Department of Veterans Affairs, Office of Policy and Planning
; Revised and Updated September,
2007
.
27
Frayne
SM
Yu
W
Em
Y
et al
Gender and use of care. Planning for Tomorrow's Veteran's Health Administration
.
J Womens Health
 
2007
;
16
(
8
):
1188
99
.
28
Friedman
JM
Schnurr
PP
.
The relationship between trauma, post-traumatic stress disorder and physical health
. In:
Friedman
JM
, ed.
Neurobiological and Clinical Consequences of Stress: From Normal Adaptation to PTSD
 .
Philadelphia, PA
:
Lipincott-Raven Publishers
;
1995
.
29
Haskell
SG
Papas
RK
Heapy
A
Reid
MC
Kerns
RD
.
The association of sexual trauma with persistent pain in a sample of women veterans receiving primary care
.
Pain Med
 
2008
;
9
(
6
):
710
7
.
30
National Pain Management Coordinating Committee. Veterans Health Administration
.
Pain as the 5th Vital Sign Toolkit
 , revised edition.
Washington DC
:
National Pain Management Coordinating Committee. Veterans Health Administration
;
2000
.
31
Cleeland
CS
Schall
M
Nolan
K
et al
Rapid improvement in pain management: The Veterans Health Administration and the Institute for Healthcare Improvement Collaborative
.
Clin J Pain
 
2003
;
19
:
298
305
.
32
Greenland
S
.
Interpretation and choice of effect measures in epidemiologic analyses
.
Am J Epidemiol
 
1987
;
125
(
5
):
761
7
.
33
Cleeland
CS
Gonin
R
Hatfield
AK
et al
Pain and its treatment in outpatients with metastatic cancer
.
NEJM
 
1994
;
330
:
592
6
.
34
Goulet
J
Fultz
S
Rimland
D
et al
Do patterns of comorbidity vary by HIV status, age, and HIV severity?
Clin Infect Dis
 
2007
;
45
:
1593
601
.
35
Lurie
N
Popkin
M
Dysken
M
, et al.
Accuracy of diagnoses of schizophrenia in Medicaid claims
.
Hosp Community Psychiatry
 
1992
;
43
:
69
71
.
36
Walkup
JT
Wei
W
Sambamoorthi
U
et al
Sensitivity of an AIDS case-finding algorithm: Who are we missing?
Med Care
 
2004
;
42
:
756
63
.
37
Hoge
CW
Clark
JC
Castro
CA
.
Commentary: Women in Combat and the risk of PTSD and Depression
.
Int J Epidemiol
 
2007
;
36
(
2
):
327
9
.
38
Larson
GE
Highfill-McRay
RM
Booth-Kemky
S
.
Psychiatric diagnosis in historic and military cohorts: Combat deployment and the healthy warrior effect
.
Am J Epidemiol
 
2008
;
167
(
11
):
1269
76
.
39
Skinner
KM
Furey
J
.
The focus on women veterans who use Veterans Administration Healthcare: The Veterans Administration women's health project
.
Mil Med
 
1998
;
163
:
761
6
.
40
Weiss
TW
.
Improvements in VA health services for women veterans
.
Womens Health
 
1995
;
23
:
1
12
.
41
Turpin
RS
Darcy
LA
Weaver
FM
Kruse
K
.
Assessing healthcare delivery to male versus female veterans
.
Womens Health
 
1992
;
18
:
81
95
.
42
Kressin
NR
Skinner
K
Sullivan
L
et al
Patient satisfaction with Department of Veterans Affairs health care: Do women differ from men?
Mil Med
 
1999
;
164
:
283
8
.
43
Bean-Mayberry
B
Chang
C
Mcneil
M
Hayes
P
Schoole
SH
.
Comprehensive care for women veterans: Indicators of dual use of VA and non-VA providers
.
J Am Womens Association
 
2004
;
59
:
192
7
.
44
Washington
DL
.
Challenges to Studying and delivering care to special populations; the example of women veterans
.
J Rehabil Res Dev
 
2004
;
41
:
7
9
.
45
Hoge
CW
Castro
CA
Messer
SC
et al
Duty in Iraq and Afghanistan, mental health problems and barriers to care
.
NEJM
 
2004
;
351
:
13
22
.
46
Dobie
DJ
Kivlahan
DR
Maynard
C
et al
Posttraumatic stress disorder in female veterans. Association with self-reported health problems and functional impairment
.
Arch Intern Med
 
2004
;
164
:
394
9
.
47
Krebs
EE
Carey
TS
Weinberger
M
.
Accuracy of the pain numeric rating scale as a screening test in primary care
.
J Gen Intern Med
 
2007
;
22
(
10
):
1453
8
.
48
Lorenz
KA
Sherbourne
CD
Shugarman
LR
et al
How reliable is pain as the 5th vital sign?
J Am Board Fam Med
 
2009
;
22
(
3
):
291
8
.
Disclaimer: The views expressed in this article are those of the authors and do not necessarily reflect the position or policy of the Department of Veterans Affairs.