Persistent Pain and Comorbidity Among Operation Enduring Freedom/Operation Iraqi Freedom/Operation New Dawn Veterans

Gender Differences in Demographic and Clinical Correlates among Veterans with Musculoskeletal Disorders

BACKGROUND

Studies suggest that women may be at greater risk for developing chronic pain and pain-related disability.

METHODS

Because musculoskeletal disorders (MSD) are the most frequently endorsed painful conditions among veterans, we sought to characterize gender differences in sociodemographic and clinical correlates among veterans upon entry into Veterans Health Administration's Musculoskeletal Disorders Cohort (n = 4,128,008).

RESULTS

Women were more likely to be younger, Black, unmarried, and veterans of recent conflicts. In analyses adjusted for gender differences in sociodemographics, women were more likely to have diagnoses of fibromyalgia, temporomandibular disorders, and neck pain. Almost one in five women (19.4%) had more than one MSD diagnosis, compared with 15.7% of men; this higher risk of MSD multimorbidity remained in adjusted analyses. Adjusting for sociodemographics, women with MSD were more likely to have migraine headache and depressive, anxiety, and bipolar disorders. Women had lower odds of cardiovascular diseases, substance use disorders, and several MSDs, including back pain conditions. Men were more likely to report "no pain" on the pain intensity Numeric Rating Scale, whereas more women (41%) than men (34%) reported moderate to severe pain (Numeric Rating Scale 4+).

CONCLUSIONS

Because women veterans are more likely to have conditions such as fibromyalgia and mental health conditions, along with greater pain intensity in the setting of MSD, women-specific pain services may be needed.

The musculoskeletal diagnosis cohort: examining pain and pain care among veterans

Musculoskeletal disorders (MSDs) are highly prevalent, painful, and costly disorders. The MSD Cohort was created to characterize variation in pain, comorbidities, treatment, and outcomes among patients with MSD receiving Veterans Health Administration care across demographic groups, geographic regions, and facilities. We searched electronic health records to identify patients treated in Veterans Health Administration who had ICD-9-CM codes for diagnoses including, but not limited to, joint, back, and neck disorders, and osteoarthritis. Cohort inclusion criteria were 2 or more outpatient visits occurring within 18 months of one another or one inpatient visit with an MSD diagnosis between 2000 and 2011. The first diagnosis is the index date. Pain intensity numeric rating scale (NRS) scores, comorbid medical and mental health diagnoses, pain-related treatments, and other characteristics were collected retrospectively and prospectively. The cohort included 5,237,763 patients; their mean age was 59, 6% were women, 15% identified as black, and 18% reported severe pain (NRS ≥ 7) on the index date. Nontraumatic joint disorder (27%), back disorder (25%), and osteoarthritis (21%) were the most common MSD diagnoses. Patients entering the cohort in recent years had more concurrent MSD diagnoses and higher NRS scores. The MSD Cohort is a rich resource for collaborative pain-relevant health service research.

The Chemokine Receptor CXCR2 Supports Nociceptive Sensitization after Traumatic Brain Injury

Abstract

Chronic pain after traumatic brain injury (TBI) is very common, but the mechanisms linking TBI to pain and the pain-related interactions of TBI with peripheral injuries are poorly understood. Chemokine receptors play an important role in both pain and brain injury. In the current work, we pursued the hypothesis that the epigenetically regulated CXC chemokine receptor 2 (CXCR2) is a crucial modulator of nociceptive sensitization induced by TBI. For these studies, we used the rat lateral fluid percussion model of TBI. Histone actyltransferase activity was blocked using anacardic acid beginning immediately following injury, or delayed for seven days prior to administration. The selective CXCR2 antagonist SCH527123 administered systemically or intrathecally was used to probe the role of chemokine signaling on mechanical hindpaw sensitization after TBI. The expression of the CXCR2 receptor was accomplished using real-time PCR, immunohistochemistry, and Western blotting, while epigenetic regulation was assessed using chromatin immunoprecipitation assay. The spinal levels of several pain-related mediators including CXCL1, an endogenous ligand for CXCR2, as well as brain-derived neurotrophic factor and prodynorphin were measured by enzyme-linked immunosorbent assay. We observed that anacardic acid potently blocked and reversed mechanical hindpaw sensitization after TBI. The same drug was able to prevent the upregulation of CXCR2 after TBI, but did not affect the spinal expression of other pain mediators. On the other hand, both systemically and intrathecally administered SCH527123 reversed hindpaw allodynia after TBI. Most of the spinal CXCR2 appeared to be expressed by spinal cord neurons. Chromatin immunoprecipitation experiments demonstrated TBI-enhanced association of the CXCR2 promoter with acetylated-H3K9 histone protein that was also reversible using anacardic acid. Taken together, our findings suggested that TBI causes the upregulation of spinal CXCR2 through an epigenetic mechanism ultimately supporting nociceptive sensitization. The use of CXCR2 antagonists may, therefore, be useful in pain resulting from TBI.

TBI-induced nociceptive sensitization is regulated by histone acetylation

Chronic pain after traumatic brain injury (TBI) is very common, but the mechanisms linking TBI to pain and the pain-related interactions of TBI with peripheral injuries are poorly understood. In these studies we pursued the hypothesis that TBI pain sensitization is associated with histone acetylation in the rat lateral fluid percussion model. Some animals received hindpaw incisions in addition to TBI to mimic polytrauma. Neuropathological analysis of brain tissue from sham and TBI animals revealed evidence of bleeding, breakdown of the blood brain barrier, in the cortex, hippocampus, thalamus and other structures related to pain signal processing. Mechanical allodynia was measured in these animals for up to eight weeks post-injury. Inhibitors of histone acetyltransferase (HAT) and histone deacetylase (HDAC) were used to probe the role of histone acetylation in such pain processing. We followed serum markers including glial fibrillary acidic protein (GFAP), neuron-specific enolase 2 (NSE) myelin basic protein (MBP) and S100β to gauge TBI injury severity. Our results showed that TBI caused mechanical allodynia in the hindpaws of the rats lasting several weeks. Hindpaws contralateral to TBI showed more rapid and profound sensitization than ipsilateral hindpaws. The inhibition of HAT using curcumin 50 mg/kg s.c reduced mechanical sensitization while the HDAC inhibitor suberoylanilide hydroxamic acid 50 mg/kg i.p. prolonged sensitization in the TBI rats. Immunohistochemical analyses of spinal cord tissue localized changes in the level of acetylation of the H3K9 histone mark to dorsal horn neurons. Taken together, these findings demonstrate that TBI induces sustained nociceptive sensitization, and changes in spinal neuronal histone proteins may play an important role.

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Pain after traumatic brain injury (TBI) is common and often persistent.

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Using the rat lateral fluid percussion model, it was observed that hindpaw allodynia is present for three weeks after TBI.

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Damage to pain processing areas of the brain can be demonstrated after TBI.

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Agents regulating the epigenetic acetylation of histone proteins modified the time course of TBI-induced allodynia.

Suicide attempts among alcohol-dependent pain patients before and after an inpatient hospitalization

BACKGROUND

This study examined (1) whether pain diagnoses were risk factors for non-fatal suicide attempts before and after inpatient hospitalizations in alcohol-dependent veterans, and (2) the characteristics of pain patients who attempted suicide.

METHOD

Administrative data from the Veterans Health Administration were used to identify veterans with an alcohol use disorder who had an inpatient hospitalization during fiscal year 2011 (n=13,047). Logistic regression analyses were used to examine the associations of suicide attempts before and after hospitalizations with pain diagnoses, demographics, medical comorbidity, and psychiatric comorbidity.

RESULTS

Bivariate analyses and analyses controlling for demographics and medical comorbidity, indicated that pain diagnoses were significantly associated with suicide attempts in the 365days before hospitalization (Odds Ratio Adjusted [OR]=1.22). This effect was not significant after controlling for psychiatric disorders. Pain diagnoses were not identified as risk factors of suicide attempts in the 365days following discharge. Subgroup analyses among only those with a pain diagnosis revealed that being younger (OR=2.64), being female (OR=2.28), and having an attempt in the year prior to hospitalization (OR=4.11) were risk factors of suicide attempts in the year following hospitalization. Additionally, younger age (OR=2.13) and depression (OR=3.53) were associated with attempts in the year prior to the hospitalization.

CONCLUSIONS

This study suggests that psychiatric disorders account for the relationship between pain diagnoses and past suicide attempts among hospitalized alcohol-dependent veterans. Pain-specific suicide prevention efforts may be better targeted at less intensive levels of care.

Predictive factors associated with success and failure for Calmare (Scrambler) therapy: a multicenter analysis

OBJECTIVE

Calmare (Scrambler) therapy is a novel therapeutic modality that purports to provide pain relief by "scrambling" afferent pain signals and replacing them with "non-pain" information through conventional lines of neural transmission. The goal of this study is to identify which factors are associated with treatment outcome for Calmare therapy.

METHODS

Data were garnered from 3 medical centers on 147 patients with various pain conditions who underwent a minimum of either 3 Calmare therapies on consecutive days or 5 therapies overall. A successful outcome was predefined as ≥50% pain relief on a 0 to 10 numerical rating scale that persisted for longer than 1 month after the last treatment. Variables evaluated for their association with outcome included age, sex, study site, baseline pain score, etiology, type of pain, diagnosis, treatment compliance, coexisting psychopathology, opioid use, antidepressant use, and membrane stabilizer use.

RESULTS

Overall, the success rate was 38.1%. Variables found to be associated with a positive outcome in multivariate logistic regression included the presence of neuropathic (OR=24.78; 95% CI, 2.47-248.97; P=0.006) or mixed (OR=10.52; 95% CI, 1.09-101.28; P=0.042) pain, and treatment at either Walter Reed (OR=6.87; 95% CI, 1.60-29.51; P=0.010) or Seoul National University (OR=12.29; 95% CI, 1.73-87.43; P=0.012). Factors that correlated with treatment failure were disease (OR=0.04; 95% CI, 0.002-0.59; P=0.020) or traumatic/surgical etiologies (OR=0.05; 95% CI, 0.005-0.56; P=0.015) and antidepressant use (OR=0.47; 95% CI, 0.18-1.02; P=0.056).

CONCLUSIONS

A neuropathic or mixed neuropathic-nociceptive pain condition was associated with a positive treatment outcome. Investigators should consider these findings when developing selection criteria in clinical trials designed to determine the efficacy of Calmare therapy.

Chronic Pain and Cognitive Behavioral Therapy

Cognitive behavioral therapy (CBT) is often used to treat chronic pain; however, more information is needed about what are the most efficacious dose and delivery methods. The aims of this review were to determine (a) which CBT doses, delivery methods, strategies, and follow-up periods have been explored in recent intervention studies of individuals with chronic pain and (b) whether the outcomes described in the selected studies were consistent with recommendations by the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials. The CINAHL, EMBASE, PubMed, PsycInfo, and SCOPUS databases were searched for randomized controlled trials published from 2009 to 2015 testing CBT for adults with chronic pain. Thirty-five studies were included in this review. Results revealed that CBT reduced pain intensity in 43% of trials, the efficacy of online and in-person formats were comparable, and military veterans and individuals with cancer-related chronic pain were understudied.

Correlates of pain symptoms among Iraq and Afghanistan military personnel following combat-related blast exposure

Pain complaints are highly prevalent among military servicemembers and Veterans of the recent combat operations in Iraq and Afghanistan. The high comorbidity of pain with conditions such as posttraumatic stress disorder (PTSD) and traumatic brain injury (TBI) underscores the importance of a greater understanding of factors associated with complex polytraumatic injuries among military personnel. The present study aimed to identify correlates of current pain among 201 U.S. military personnel who reported at least one blast experience during combat deployment (age [mean +/– standard deviation]: 27.20 +/– 7.58 yr). Theoretically derived subsets of variables were analyzed in successive hierarchical regression models to determine correlates of self-reported pain symptoms. Preliminary models evaluated demographic features, medical and injury characteristics (e.g., TBI classification), psychosocial history (e.g., trauma exposure), and psychiatric variables. A final model was then derived, in which older age, possible or probable mild TBI, depression symptoms, and PTSD re-experiencing symptoms emerged as significant correlates of pain. The findings further the understanding of polytrauma symptoms among military personnel by identifying specific patient characteristics and comorbidity patterns related to pain complaints. Increased awareness of demographic, psychiatric, or medical factors implicated in pain will enhance comprehensive clinical assessment and intervention efforts.

Chronic pain acceptance incrementally predicts disability in polytrauma-exposed veterans at baseline and 1-year follow-up

War veterans are at increased risk for chronic pain and co-occurring neurobehavioral problems, including posttraumatic stress disorder (PTSD), depression, alcohol-related problems, and mild traumatic brain injury (mTBI). Each condition is associated with disability, particularly when co-occurring. Pain acceptance is a strong predictor of lower levels of disability in chronic pain. This study examined whether acceptance of pain predicted current and future disability beyond the effects of these co-occurring conditions in war veterans. Eighty trauma-exposed veterans with chronic pain completed a PTSD diagnostic interview, clinician-administered mTBI screening, and self-report measures of disability, pain acceptance, depression, and alcohol use. Hierarchical regression models showed pain acceptance to be incrementally associated with disability after accounting for symptoms of PTSD, depression, alcohol-related problems, and mTBI (total adjusted R(2) = .57, p < .001, ΔR(2) = .03, p = .02). At 1-year follow-up, the total variance in disability accounted for by the model decreased (total adjusted R(2) = .29, p < .001), whereas the unique contribution of pain acceptance increased (ΔR(2) = .07, p = .008). Pain acceptance remained significantly associated with 1-year disability when pain severity was included in the model. Future research should evaluate treatments that address chronic pain acceptance and co-occurring conditions to promote functional recovery in the context of polytrauma in war veterans.

The association between chronic pain and obesity

Obesity and pain present serious public health concerns in our society. Evidence strongly suggests that comorbid obesity is common in chronic pain conditions, and pain complaints are common in obese individuals. In this paper, we review the association between obesity and pain in the general population as well as chronic pain patients. We also review the relationship between obesity and pain response to noxious stimulation in animals and humans. Based upon the existing research, we present several potential mechanisms that may link the two phenomena, including mechanical/structural factors, chemical mediators, depression, sleep, and lifestyle. We discuss the clinical implications of obesity and pain, focusing on the effect of weight loss, both surgical and noninvasive, on pain. The literature suggests that the two conditions are significant comorbidities, adversely impacting each other. The nature of the relationship however is not likely to be direct, but many interacting factors appear to contribute. Weight loss for obese pain patients appears to be an important aspect of overall pain rehabilitation, although more efforts are needed to determine strategies to maintain long-term benefit.

Smoking Status and Pain Intensity Among OEF/OIF/OND Veterans

OBJECTIVE

Pain and smoking are highly prevalent among Veterans. Studies in non-Veteran populations have reported higher pain intensity among current smokers compared with nonsmokers and former smokers. We examined the association of smoking status with reported pain intensity among Veterans of Operations Enduring Freedom, Iraqi Freedom, and New Dawn (OEF/OIF/OND).

DESIGN

The sample consisted of OEF/OIF/OND Veterans who had at least one visit to Veterans Affairs (2001-2012) with information in the electronic medical record for concurrent smoking status and pain intensity. The primary outcome measure was current pain intensity, categorized as none to mild (0-3); moderate (4-6); or severe (≥7); based on a self-reported 11-point pain numerical rating scale. Multivariable logistic regression analyses were used to assess the association of current smoking status with moderate to severe (≥4) pain intensity, controlling for potential confounders.

RESULTS

Overall, 50,988 women and 355,966 men Veterans were examined. The sample mean age was 30 years; 66.3% reported none to mild pain; 19.8% moderate pain; and 13.9% severe pain; 37% were current smokers and 16% former smokers. Results indicated that current smoking [odds ratio (OR) = 1.29 (95% confidence intervals (CI) = 1.27-1.31)] and former smoking [OR = 1.02 (95% CI = 1.01-1.05)] were associated with moderate to severe pain intensity, controlling for age, service-connected disability, gender, obesity, substance abuse, mood disorders, and Post Traumatic Stress Disorder.

CONCLUSIONS

We found an association between current smoking and pain intensity. This effect was attenuated in former smokers. Our study highlights the importance of understanding reported pain intensity in OEF/OIF/OND Veterans who continue to smoke.

Deployment-related psychiatric and behavioral conditions and their association with functional disability in OEF/OIF/OND veterans

Understanding the factors that influence veterans' functional outcome after deployment is critical to provide appropriately targeted care. Mild traumatic brain injury (mTBI) and posttraumatic stress disorder (PTSD) have been related to disability, but other psychiatric and behavioral conditions are not as well examined. We investigated the impact of deployment-related psychiatric and behavioral conditions on disability among 255 OEF/OIF/OND service members and veterans. Structured clinical interviews assessed TBI and the psychiatric conditions of depression, PTSD, anxiety, and substance use. Self-report questionnaires assessed disability and the behavioral conditions of sleep disturbance and pain. Over 90% of participants had a psychiatric and/or behavioral condition, with approximately half presenting with ≥ 3 conditions. Exploratory factor analysis revealed 4 clinically relevant psychiatric and behavioral factors which accounted for 76.9% of the variance: (a) depression, PTSD, and military mTBI (deployment trauma factor); (b) pain and sleep (somatic factor); (c) anxiety disorders, other than PTSD (anxiety factor); and (d) substance abuse or dependence (substance use factor). Individuals with the conditions comprising the deployment trauma factor were more likely to be substantially disabled than individuals with depression and PTSD, but no military mTBI, OR = 3.52; 95% CI [1.09, 11.37]. Depression, PTSD, and a history of military mTBI may comprise an especially harmful combination associated with high risk for substantial disability.

Anxiety and substance use disorders: co-occurrence and clinical issues

The co-occurrence of substance use disorders (SUDs) and anxiety disorders has been now well established. This association is frequent and can be explained by three models: the shared vulnerability factors model, the self-medication model, and the substance-induced model. General population epidemiological studies provide strong evidence of the frequency of the association for the most used substances: tobacco, alcohol, cannabis, and to a lesser extent sedatives, opiates, and cocaine. For substances that are less commonly used in the general population, the frequency of the co-occurrence can more precisely be studied in clinical samples. We provide the most recent literature results on the association of SUDs and anxiety, and evidence for one explicative model or the other when available. For substances with sedative properties (alcohol, benzodiazepines, cannabis, opioids), both evidence for a self-medication and for a toxic effect exist. For substances with psychostimulant properties (tobacco, cocaine, and amphetamines), the literature favors the toxic hypothesis to explain the association with anxiety disorders. We give practical steps for the recognition of these dual diagnoses and present therapeutic issues, although the strategies are rarely evidence based.

CAM utilization among OEF/OIF veterans: findings from the National Health Study for a New Generation of US Veterans

BACKGROUND

Complementary and alternative medicine (CAM) is increasingly seen as an adjunct to traditional plans of care. This study utilized a representative sample of Operation Enduring Freedom and Operation Iraqi Freedom (OEF/OIF) veterans and OEF/OIF-era veterans to explore the prevalence and characteristics of CAM users.

RESEARCH DESIGN

The National Health Study for a New Generation of US Veterans (NewGen) is a longitudinal health study of a population-based cohort of OEF/OIF (deployed) and OEF/OIF-era (nondeployed) veterans. Data from the 2009-2011 NewGen survey (n=20,563) were analyzed to determine prevalence of CAM use by demographic and military characteristics, the types of CAM modalities used, and where the modalities were sought. Results were weighted to the entire population of OEF/OIF and OEF/OIF-era veterans.

RESULTS

There was no statistically significant association between CAM use and deployment. Those who used Department of Veterans Affairs (VA) health care after separation were more likely to be CAM users compared with those who did not use VA care; however, the majority of veterans using CAM are using it outside the VA health care system. Massage was the most prevalent CAM modality followed by chiropractic treatment; males were less likely to use CAM than women.

CONCLUSIONS

CAM modalities are being utilized by OEF/OIF veterans for health problems mainly outside the VA. Policymakers should determine appropriate use of these modalities.

Medical illness burden is associated with greater PTSD service utilization in a nationally representative survey

OBJECTIVE

Posttraumatic stress disorder (PTSD) is associated with higher rates of many medical conditions and higher use of medical health care services. Growing evidence suggests that comorbid medical illness in PTSD may in turn be associated with greater use of mental health treatment. However, no study to date has examined the impact of cumulative medical illness burden on PTSD service utilization.

METHOD

Data come from the second wave of the National Epidemiologic Survey on Alcohol and Related Conditions. PTSD was assessed via structured interview, and cumulative medical illness burden was assessed via a survey of medical conditions. Logistic regression modeling examined associations between cumulative medical illness burden and odds of receiving PTSD treatment.

RESULTS

In the final sample of 1599 individuals with current PTSD, controlling for demographic characteristics, insurance status, psychiatric comorbidity and PTSD symptom count, higher levels of past-year medical illness were associated with increased odds of receiving past-year treatment for PTSD (odds ratio = 1.10, 95% confidence interval = 1.01-1.20, P = .029).

CONCLUSIONS

Greater levels of medical illness are associated with increased odds of PTSD service utilization. Greater medical comorbidity may increase the need for PTSD care by exacerbating symptoms or increase contact with medical services promoting PTSD detection and treatment.

Differential Expression of Brain Cannabinoid Receptors between Repeatedly Stressed Males and Females may Play a Role in Age and Gender-Related Difference in Traumatic Brain Injury: Implications from Animal Studies

Inconsistent gender differences in the outcome of TBI have been reported. The mechanism is unknown. In a recent male animal study, repeated stress followed by TBI had synergistic effects on brain gene expression and caused greater behavioral deficits. Because females are more likely to develop anxiety after stress and because anxiety is mediated by cannabinoid receptors (CBRs) (CB₁ and CB₂), there is a need to compare CB₁ and CB₂ expression in stressed males and females. CB₁ and CB₂ mRNA expression was determined in the amygdala, hippocampus, prefrontal cortex (PFC), and hypothalamus of adolescent male and female rats after 3 days of repeated tail-shock stress using qPCR. PFC CB₁ and CB₂ protein levels were determined using Western blot techniques. Both gender and stress had significant effects on brain CB₁ mRNA expression levels. Overall, females showed significantly higher CB₁ and CB₂ mRNA levels in all brain regions than males (p < 0.01). Repeated stress reduced CB₁ mRNA levels in the amygdala, hippocampus, and PFC (p < 0.01, each). A gender × stress interaction was found in CB₁ mRNA level in the hippocampus (p < 0.05), hypothalamus (p < 0.01), and PFC (p < 0.01). Within-sex one-way ANOVA analysis showed decreased CB₁ mRNA in the hippocampus, hypothalamus, and PFC of stressed females (p < 0.01, each) but increased CB₁ mRNA levels in the hypothalamus of stressed males (p < 01). There was a gender and stress interaction in prefrontal CB₁ receptor protein levels (p < 0.05), which were decreased in stressed females only (p < 0.05). Prefrontal CB₂ protein levels were decreased in both male and female animals after repeated stress (p < 0.05, each). High basal levels of CBR expression in young naïve females could protect against TBI damage whereas stress-induced CBR deficits could predict a poor outcome of TBI in repeatedly stressed females. Further animal studies could help evaluate this possibility.