The association between chronic pain and obesity

Diet can exert both analgesic and pronociceptive effects in acute and chronic pain models: a systematic review of preclinical studies

BACKGROUND

Although diet is an essential aspect of human health, the link between diet and pain is still not well understood. Preclinical animal research provides information to understand underlying mechanisms that allow identifying the needs for human research.

OBJECTIVES

This study aims to give a systematic overview of the current evidence from preclinical studies regarding the analgesic and pronociceptive effects of various diets in non-neuropathic, non-cancer, or non-visceral acute and chronic pain models.

STUDY DESIGN

A systematic Review.

SETTING

This study examined studies that investigate the analgesic and pronociceptive effects of various diets in non-neuropathic, non-cancer, or non-visceral acute and chronic pain models.

METHODS

This review was conducted following the PRISMA guidelines and was registered in PROSPERO with the registration number CRD42019133473. The certainty of evidence was examined by a modified GRADE approach.

RESULTS

After the screening process twenty-four eligible papers were included in this review. Nineteen studies examined acute pain, nine studies chronic inflammatory pain, and four studies assessed both acute and chronic pain models.

LIMITATIONS

Due to the heterogeneity of the included studies, a meta-analysis was not included in this study.

CONCLUSIONS

In animal models, excessive saturated, monounsaturated or omega-6 polyunsaturated fat ingestion and diets rich in fats and carbohydrates can decrease pain sensitivity in acute nociceptive pain, whereas it can induce mechanical allodynia and heat hyperalgesia in chronic inflammatory pain. Additionally, diets rich in anti-inflammatory ingredients, as well as a calorie-restricted diet can promote recovery from primary mechanical allodynia and heat hyperalgesia in chronic inflammatory pain.

Pressure pain thresholds in individuals with knee pain: a cross-sectional study

Background

Knee osteoarthritis (KOA), chronic widespread pain (CWP) and overweight/obesity are public health problems that often coincide, and there is a multifactorial and unclear relationship between them. The study aimed to (1) investigate pain sensitivity, assessed by pressure pain thresholds (PPTs), among women and men with knee pain and (2) associations with, respectively, radiographic KOA (rKOA), CWP, and overweight/obesity.

Methods

Baseline data from an ongoing longitudinal study involving 280 individuals with knee pain in the 30–60 age group. Pain sensitivity was assessed by PPTs on eight different tender points using a pressure algometer. The participants’ knees were x-rayed. Self-reported CWP and number of pain sites were assessed with a pain figure, and overweight/obesity was measured using body mass index (BMI), visceral fat area (VFA), and body fat percentage, assessed with a bioimpedance. Associations were analysed using regression analyses.

Results

Women reported lower PPTs than men (p < 0.001), but no PPTs differences were found between those with and without rKOA. Low PPTs was associated with female sex, more pain sites, CWP, and a higher VFA and body fat percentage. The tender points second rib and the knees were most affected. The prevalence of CWP was 38 %.

Conclusions

The modifiable factors, increased VFA, and body fat could be associated with increased pain sensitivity among individuals with knee pain. Longitudinal studies are needed to further investigate the associations.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04408-0.

Perioperative factors associated with persistent post-surgical pain after hysterectomy, cesarean section, prostatectomy, and donor nephrectomy: a systematic review and meta-analysis

ABSTRACT

Persistent postsurgical pain (PPSP) is a common, and often disabling postoperative morbidity, but many questions remain about factors associated with PPSP. This systematic review and meta-analysis aimed to identify preoperative, intraoperative and postoperative factors associated with PPSP after gynecological surgeries, namely hysterectomy and cesarean section (C-section), and urological surgeries, namely prostatectomy and donor nephrectomy. Overall, 18 gynecological surgery studies, 4 prostatectomy studies, and 2 donor nephrectomy studies met the review criteria providing data that could be meta-analyzed. Average (±SD) PPSP occurrence after gynecological surgery was 20±11%; factors associated with increased risk of PPSP included smoking, preoperative abdominal or pelvic pain, preoperative pain elsewhere in the body, longer duration of surgery, more intense acute postoperative pain, and surgical wound infection. The use of neuraxial anesthesia was associated with decreased PPSP risk. Average PPSP occurrence was 20±9% after prostatectomy and 15±2% after donor nephrectomy. For urological procedures, the existing data did not allow for identification of significant factors associated with PPSP, except for laparoscopic and hand assisted laparoscopic approaches that were associated with lower incidence of PPSP for donor nephrectomy, and the use of neuraxial anesthesia which was associated with lower incidence of PPSP after prostatectomy. PPSP after gynecological and urological surgeries is common. This systematic review identified important factors associated with C-section and hysterectomy that can help identify women who are at high risk of PPSP. More high-quality studies with consistent methodology are needed to understand the factors associated with PPSP risk, particularly for surgeries such as prostatectomy and nephrectomy.

The sex difference in gait speed among older adults: how do sociodemographic, lifestyle, social and health determinants contribute?

Background

This study explores whether a sex difference in sensitivity to (strength of the association) and/or in exposure to (prevalence) determinants of gait speed contributes to the observed lower gait speed among older women compared to men.

Methods

Data from the Longitudinal Aging Study Amsterdam (LASA) were used. In total 2407 men and women aged 55–81 years were included, with baseline measurements in 1992/2002 and follow-up measurements every 3–4 years for 15/25 years. Multivariable mixed model analysis was used to investigate sex differences in sensitivity (interaction term with sex) and in exposure to (change of the sex difference when adjusted) socio-demographic, lifestyle, social and health determinants of gait speed.

Results

Women had a 0.054 m/s (95 % CI: 0.076 − 0.033, adjusted for height and age) lower mean gait speed compared to men. In general, men and women had similar determinants of gait speed. However, higher BMI and lower physical activity were more strongly associated with lower gait speed in women compared to men (i.e. higher sensitivity). More often having a lower educational level, living alone and having more chronic diseases, pain and depressive symptoms among women compared to men also contributed to observed lower gait speed in women (i.e. higher exposure). In contrast, men more often being a smoker, having a lower physical activity and a smaller personal network size compared to women contributed to a lower gait speed among men (i.e. higher exposure).

Conclusions

Both a higher sensitivity and higher exposure to determinants of gait speed among women compared to men contributes to the observed lower gait speed among older women. The identified (modifiable) contributing factors should be taken into account when developing prevention and/or treatment strategies aimed to enhance healthy physical aging. This might require a sex-specific approach in both research and clinical practice, which is currently often lacking.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-021-02279-7.

Association between muscle strength, upper extremity fatigue resistance, work ability and upper extremity dysfunction in a sample of workers at a tertiary hospital

Background

Upper extremity musculoskeletal disorders negatively affect ability to perform activities of daily living, self-care and work. Therefore, outcome measurements that address muscle strength, fatigue resistance, functionality and work physical capacity must be defined to assess and plan specific actions to minimize them.

Objective

To investigate the association of upper extremity muscle strength with upper extremity fatigue resistance, work ability and upper extremity dysfunction in a sample of workers from a tertiary hospital.

Methods

Shoulder and elbow isokinetic strength were assessed by Biodex System 4™, isometric hand grip by JAMAR™, upper extremity fatigue resistance by Functional Impairment Test Hand and Neck/Shoulder/Arm (FIT-HaNSA), ability to work by the Work Ability Index and upper extremity dysfunction by the Quick-Disabilities of the Arm, Shoulder and Hand QuickDASH-Br questionnaire. The Nordic questionnaire and Numeric Pain Rating Scale (NPRS) were used for pain description. The associations were analysed by Spearman’s correlation coefficient (rho) (p < 0.05).

Results

Twenty-seven participants: 59.2% women; mean age 46 years old; 70.3% obese/overweight; 62.9% active with predominantly dynamic muscle contraction work. Besides predominance of good to moderate work ability (81.4%) and comorbidities (37%), all participants had symptoms of the upper extremities for at least 12 months, with a predominance of low-intensity in the shoulder (55.5%). In addition, 88.8% reported pain in other segments. Muscle strength of abduction (rho = 0.49), adduction (rho = 0.40), internal rotation (rho = 0.44) and hand grip (rho = 0.68) presented moderate correlation with FIT-HaNSA. Hand grip (rho = − 0.52) showed moderate correlation with upper extremity dysfunction.

Conclusions

The results of this preliminary study suggested the association of shoulder strength with fatigue resistance. Also, hand grip strength was associated with upper extremity dysfunction and fatigue resistance. No association was found with the Work Ability Index in this sample. So, it is suggested that hand grip and shoulder strength could be outcome measurements used for future interventions focused on upper extremity preventive exercises to improve strength and fatigue resistance of workers at risk for the development of musculoskeletal disorders. Other individual, psychosocial and organizational risk factors must also be considered as influences on upper extremity function.

Impact of body mass index on opioid consumption in lumbar spine fusion surgery

Background

in the United States from 1999 to 2000 through 2017–2018, the prevalence of obesity increased from 30.5 to 42.4%, while the prevalence of severe obesity nearly doubled. In lumbar spine surgery, obesity is associated with increased complications, worse perioperative outcomes, and higher costs. The purpose of this study was to examine the association between body mass index (BMI) and opioid consumption in patients undergoing lumbar spine fusion surgery. We hypothesized that obese patients would require more opioids postoperatively.

Methods

retrospective review of 306 patients who underwent one- or two-level posterior lumbar interbody fusion surgery between 2016 and 2020. Patients were stratified by BMI as follows: normal weight (18.5–24.9 kg/m2), overweight (25.0–29.9 kg/m2), obese I (30.0–34.9 kg/m2), and obese II–III (≥ 35.0 kg/m2). Patient demographics and preoperative characteristics were compared across BMI cohorts using one-way ANOVA and chi-square analysis. Patients with prior history of opioid use were excluded. Primary outcome measure was postoperative opioid consumption. Secondary outcomes included operative time, length of stay (LOS), discharge destination, and 30-day re-encounter rates. Outcomes were analyzed using multivariable linear regression adjusted for potential confounders.

Results

of 306 total patients, 17.3% were normal weight, 39.9% were overweight, 25.5% were obese I, and 17.3% were obese II–III. Obesity was associated with longer operative times and length of stay (p < 0.001, p = 0.024). For opioid naïve patients, there was no difference in-house opioid consumption when adjusted for kilograms of body mass and LOS (p = 0.083). Classes II–III patients were prescribed more than twice the number of postoperative opioids (p < 0.001) and were on opioids for a longer time postoperatively (p = 0.019).

Conclusion

obesity is associated with longer operative times, longer LOS, and increased consumption of postoperative opioids. This should be considered when counseling patients preoperatively prior to lumbar spine fusion procedures.

Elevated dietary ω-6 polyunsaturated fatty acids induce reversible peripheral nerve dysfunction that exacerbates comorbid pain conditions

Chronic pain is the leading cause of disability worldwide¹ and is commonly associated with comorbid disorders². However, the role of diet in chronic pain is poorly understood. Of particular interest is the Western-style diet, enriched with ω-6 polyunsaturated fatty acids (PUFAs) that accumulate in membrane phospholipids and oxidise into pronociceptive oxylipins^3,4. Here we report that mice administered an ω-6 PUFA-enriched diet develop persistent nociceptive hypersensitivities, spontaneously active and hyper-responsive glabrous afferent fibres and histologic markers of peripheral nerve damage reminiscent of a peripheral neuropathy. Linoleic and arachidonic acids accumulate in lumbar dorsal root ganglia, with increased liberation via elevated phospholipase (PLA)2 activity. Pharmacological and molecular inhibition of PLA2G7 or diet reversal with high levels of ω-3 PUFAs attenuate nociceptive behaviours, neurophysiologic abnormalities and afferent histopathology induced by high ω-6 intake. Additionally, ω-6 PUFA accumulation exacerbates allodynia observed in preclinical inflammatory and neuropathic pain models and is strongly correlated with multiple pain indices of clinical diabetic neuropathy. Collectively, these data reveal dietary enrichment with ω-6 PUFAs as a new aetiology of peripheral neuropathy and risk factor for chronic pain and implicate multiple therapeutic considerations for clinical pain management.

BMI but not age and sex negatively impact on the outcome of pharmacotherapy in fibromyalgia: a systematic review

INTRODUCTION

The impact of sex, age, body mass index (BMI) in fibromyalgia is still unclear. A systematic review was conducted to investigate whether sex, age and BMI influence the clinical outcomes and rate of adverse events.

METHODS

The present study was performed according to the PRISMA guidelines. The literature search was performed in February 2021. All the RCTs investigating pharmacological strategies for fibromyalgia were accessed.

RESULTS

Data from 51 RCTs (17,311 patients) were collected. Short Form 36 emotional, Social function and physical role subscales showed evidence of a negative association with BMI (P = 0.02, P = 0.002 and P = 0.0001, respectively). Depression and anxiety subscales of the Hospital Anxiety and Depression score demonstrated evidence of a positive association with age (P = 0.04 and P = 0.001, respectively) and sex (P = 0.00005 and P = 0.0001, respectively). Visual analog scale evidenced a positive association with BMI (P = 0.04). Clinical Global Impression Severity scale demonstrated evidence of a negative association with BMI (P = 0.02).

CONCLUSION

Irrespective from the pharmacological approach, a higher BMI is negatively associated with a favorable outcome in patients with fibromyalgia. The association with sex and age remains controversial.

LEVEL OF EVIDENCE

I, systematic review of RCTs.

Circulating Adipokines in Predicting the Transition from Acute to Persistent Low Back Pain

OBJECTIVES

Cytokines such as tumor necrosis factor (TNF) contribute to the transition from acute to persistent pain. Despite increasing incidence of obesity and its linkage with chronic pain and inflammation, cytokines predominantly produced by adipose tissue (adipokines) have received little attention. Here we aimed to explore the longitudinal trajectory of adipokines from the onset of acute low back pain (LBP) and identify combinations of adipokines and/or other features that predict outcome.

METHODS

Individuals with acute LBP (less than two weeks after onset) who had either recovered (no pain, N = 15) or remained unrecovered (no reduction/increase in pain, N = 13) at six months and 15 controls were retrospectively selected from a larger prospective cohort. Participants provided blood for the measurement of TNF, interleukin-6 (IL-6), resistin, visfatin, adiponectin, leptin, and C-reactive protein (CRP), and completed questionnaires related to pain/disability, depression, and sleep at baseline. LBP participants repeated measurements at six months.

RESULTS

Compared with controls, acute LBP individuals had higher TNF and CRP but lower adiponectin. In LBP, unrecovered individuals had higher TNF at both time points, but lower CRP at baseline and leptin at six months. Although combined low CRP, high TNF, and depressive symptoms at baseline predicted poor recovery, the primary adipokines leptin, resistin, visfatin, and adiponectin did not.

CONCLUSIONS

Primary adipokines did not add to the prediction of poor LBP outcome that has been identified for the combination of low CRP, high TNF, and depressive symptoms in acute LBP. Whether adipokines play a role in LBP persistence in overweight/obese individuals requires investigation.

Nationwide Cross-Sectional Study of the Association between Knee Pain and Weight Change: Analysis of the Korea National Health and Nutrition Examination Survey (KNHANES 2013-2015)

The knee is a hinge joint that provides stability and control, which are essential in daily life. Obesity is a major cause of knee pain and its incidence continues to increase worldwide. In this study, we analyzed Korea National Health and Nutrition Examination Survey data on the general population, and showed an association between weight change and knee pain. A total of 22,948 participants were enrolled; those under the age of 50 and those who did not answer the questions about knee pain or weight change were excluded. In all, 8480 patients were analyzed, 7001 (82.56%) of whom indicated that they did not have knee pain, versus 1479 (17.44%) who did experience knee pain. Multivariate regression analysis was performed to analyze the association between knee pain and weight change. With full adjustment for covariates, weight gain per se (OR 1.37; p = 0.002), and gains of 3–6 kg (OR 1.28; p = 0.029) and ≥6 kg (OR 1.62; p = 0.012), showed significant associations with knee pain. This cross-sectional study confirmed a significant association between knee pain and weight change. Therefore, when evaluating patients with knee pain, it is necessary to evaluate weight gain.

A qualitative investigation of a prenatal yoga intervention to prevent excessive gestational weight gain: A thematic analysis of interviews

PURPOSE

To describe pregnant women's experiences and perceived facilitators/barriers of a prenatal yoga intervention to prevent excessive gestational weight gain (EGWG).

METHODS

Pregnant women (N = 13) were interviewed after participation in a 12-week prenatal yoga intervention to prevent EGWG. Interviews were summarized using thematic analysis.

RESULTS

Twelve themes were identified and organized into four categories: 1) experiences of prenatal yoga (positive experience/enjoyment, pain relief, connecting to body), 2) prenatal yoga and weight (increased mindfulness/self-awareness, increased physical activity, weight management), 3) barriers to prenatal yoga (physical body, commute/traffic, schedule), and 4) facilitators of prenatal yoga (healthy pregnancy, support from other pregnant women, the feeling from prenatal yoga).

CONCLUSION

Prenatal yoga may relieve pain and help women be more connected to their bodies. Prenatal yoga may also help women become more aware of their health behaviors and increases their physical activity which may have important implications for reducing EGWG.

Pain and Obesity in Autosomal Dominant Polycystic Kidney Disease: A Post Hoc Analysis of the Halt Progression of Polycystic Kidney Disease (HALT-PKD) Studies

Rationale & Objective

Pain is a frequent complication of autosomal dominant polycystic kidney disease (ADPKD) and includes back and abdominal pain. We hypothesized that in adults with early- and late-stage ADPKD, overweight and obesity are independently associated with greater self-reported back, abdominal, and radicular pain at baseline and that weight loss would be associated with decreased pain over a follow-up period.

Study Design

Post hoc analysis of pooled data from 2 randomized trials.

Setting & Participants

Participants in the HALT-PKD study A or B. 867 individuals were included in a cross-sectional analysis. 4,248 observations from 871 participants were included in a longitudinal analysis.

Predictor

Overweight and obesity (cross-sectional); annual change in weight as a time-varying predictor (longitudinal).

Outcome

Pain (Likert-scale responses; cross-sectional); annual change in pain (binary outcome of worsening pain or not worsening; longitudinal).

Analytical Approach

Multivariable ordinal logistic regression (cross-sectional); generalized estimating equation analysis (longitudinal).

Results

Participants were aged 42±10 years and baseline estimated glomerular filtration rate was 71±26 mL/min/1.73 m². Back, abdominal, and radicular pain were reported more frequently in individuals with increasing body mass index category (all P < 0.05 for trend). After multivariable adjustment, obesity was associated with increased odds of greater back and radicular pain, but not abdominal pain. Associations remained similar after further adjustment for baseline height-adjusted kidney and liver volume (study A only, n = 457); back pain: OR, 1.88 (95% CI, 1.15-3.08); and radicular pain: OR, 2.92 (95% CI, 1.45-5.91). Longitudinally (median follow-up, 5 years), weight loss (annual decrease in weight ≥ 4%) was associated with decreased adjusted odds of worsening back pain (OR, 0.87 [95% CI, 0.76-0.99]) compared with the reference group (stable weight).

Limitations

Post hoc, associative analysis.

Conclusions

In early- and late-stage ADPKD, obesity was associated with greater back and radicular pain independent of total kidney/liver volume. Mild weight loss was associated with favorable effects on back pain.

Preoperative chronic opioid use and its impact on early complications in bariatric surgery: a Swedish nationwide cohort study of 56,183 patients

BACKGROUND

The association between severe obesity and chronic pain makes opioid use common among bariatric patients. Preoperative opioid use has been identified as a risk factor in other surgical procedures.

OBJECTIVES

To examine the impact of preoperative opioid use on complications after primary bariatric surgery.

SETTING

Sweden.

METHODS

All primary laparoscopic Roux-en-Y gastric bypass (LRYGB) and laparoscopic sleeve gastrectomy (LSG) patients from 2007-2017 were identified in the Scandinavian Obesity Surgery Register. Prescriptions for opioids within 90 days prior to surgery were retrieved from the Swedish Prescribed Drug Register and converted into oral morphine equivalents (OMEs). Patients with ≥2 prescription of opioids within 90 days prior to surgery were defined as chronic opioid users. Generalized linear regression was used to adjust for age, sex, body mass index, procedure type, year of operation, and co-morbidities.

RESULTS

Of the 56,183 patients who had undergone primary LRYGB (n = 49,615) or LSG (n = 6568), 17.5% (n = 9825) had at least 1 prescription of opioids prior to surgery, of which 4.3% (n = 2390) were defined as chronic opioid users. Chronic opioid use was associated with a higher risk of severe complications (Clavien Dindo grade ≥ 3b; odds ratio [OR], 1.67; 95% confidence interval [CI], 1.37-2.04), increased lengths of stay (relative risk, 1.11; 95% CI, 1.08-1.14), and higher rates of readmission (OR, 1.70; 95% CI, 1.49-1.94) and reoperation (OR, 1.87; 95% CI, 1.53-2.27; all P values < .001). Furthermore, higher OME exposure was associated with stepwise higher risks.

CONCLUSION

Preoperative opioid use was an independent risk factor for severe complications, as well as prolonged lengths of stay, readmission, and reoperation after primary bariatric surgery.

Mediterranean diet and changes in frequency, severity and localization of pain in older adults: The Seniors-ENRICA cohorts

BACKGROUND

Although some components of the Mediterranean diet have shown benefits in pain risk through its anti-inflammatory/antioxidant properties, no population-based studies have investigated the effect of adherence to this diet on changes in pain over time.

METHODS

We used data from 864 and 862 older adults recruited in the Seniors-ENRICA-1 and Seniors-ENRICA-2 cohorts and followed-up for 2.8 and 2.4 years, respectively. Adherence to the Mediterranean diet was assessed with the MEDAS score at baseline. Frequency, severity and locations of pain obtained at baseline and follow-up were used to compute a pain scale. Analyses were performed using multinomial logistic regression models, and adjusted for the main confounders.

RESULTS

Participants had a mean (SD) age of 71.5 (5.1) years, 36.8% were men and 78.3% had chronic conditions. In the pooled cohorts, compared with participants in the lowest quartile of the MEDAS score (lowest adherence to the Mediterranean diet), those in the highest quartile showed a higher frequency of pain improvement versus worsening (relative risk ratio [95% confidence interval]: 1.43 [1.03,1.99]). This association was also evidenced in two components of the pain scale: improvement in pain severity (1.43 [1.01,2.04]) and reduction in pain locations (1.54 [1.08,2.20]), but a tendency to pain frequency improvement (1.34 [0.92,1.93]) was also observed. The main contributors to these associations were high consumption of fruit and vegetables, and low consumption of sugar-sweetened beverages.

CONCLUSIONS

A higher adherence to the Mediterranean diet was related to a subsequent improvement in pain characteristics in older adults, suggesting that improving diet quality may help reduce the high health impact of pain.

Pain Trends Among American Adults, 2002-2018: Patterns, Disparities, and Correlates

Determining long-term trends in chronic pain prevalence is critical for evaluating and shaping U.S. health policies, but little research has examined such trends. This study (1) provides estimates of pain trends among U.S. adults across major population groups; (2) tests whether sociodemographic disparities in pain have widened or narrowed over time; and (3) examines socioeconomic, behavioral, psychological, and medical correlates of pain trends. Regression and decomposition analyses of joint, low back, neck, facial/jaw pain, and headache/migraine using the 2002-2018 National Health Interview Survey for adults aged 25-84 (N  =  441,707) assess the trends and their correlates. We find extensive escalation of pain prevalence in all population subgroups: overall, reports of pain in at least one site increased by 10%, representing an additional 10.5 million adults experiencing pain. Socioeconomic disparities in pain are widening over time, and psychological distress and health behaviors are among the salient correlates of the trends. This study thus comprehensively documents rising pain prevalence among Americans across the adult life span and highlights socioeconomic, behavioral, and psychological factors as important correlates of the trends. Chronic pain is an important dimension of population health, and demographic research should include it when studying health and health disparities.

Diet-induced obesity leads to behavioral indicators of pain preceding structural joint damage in wild-type mice

Introduction

Obesity is one of the largest modifiable risk factors for the development of musculoskeletal diseases, including intervertebral disc (IVD) degeneration and back pain. Despite the clinical association, no studies have directly assessed whether diet-induced obesity accelerates IVD degeneration, back pain, or investigated the biological mediators underlying this association. In this study, we examine the effects of chronic consumption of a high-fat or high-fat/high-sugar (western) diet on the IVD, knee joint, and pain-associated outcomes.

Methods

Male C57BL/6N mice were randomized into one of three diet groups (chow control; high-fat; high-fat, high-sugar western diet) at 10 weeks of age and remained on the diet for 12, 24, or 40 weeks. At endpoint, animals were assessed for behavioral indicators of pain, joint tissues were collected for histological and molecular analysis, serum was collected to assess for markers of systemic inflammation, and IBA-1, GFAP, and CGRP were measured in spinal cords by immunohistochemistry.

Results

Animals fed obesogenic (high-fat or western) diets showed behavioral indicators of pain beginning at 12 weeks and persisting up to 40 weeks of diet consumption. Histological indicators of moderate joint degeneration were detected in the IVD and knee following 40 weeks on the experimental diets. Mice fed the obesogenic diets showed synovitis, increased intradiscal expression of inflammatory cytokines and circulating levels of MCP-1 compared to control. Linear regression modeling demonstrated that age and diet were both significant predictors of most pain-related behavioral outcomes, but not histopathological joint degeneration. Synovitis was associated with alterations in spontaneous activity.

Conclusion

Diet-induced obesity accelerates IVD degeneration and knee OA in mice; however, pain-related behaviors precede and are independent of histopathological structural damage. These findings contribute to understanding the source of obesity-related back pain and the contribution of structural IVD degeneration.

Exploring factors associated with pain in hemodialysis patients: a multicenter cross-sectional study from Palestine

BACKGROUND

Chronic kidney disease (CKD) is a rising medical concern around the world. End-stage kidney disease (ESKD) is the last stage of CKD stages that necessitates renal replacement therapy (RRT), such as hemodialysis (HD), which seems to be the most commonly used type. However, patients on HD still suffer from high mortality and morbidity rates compared to those who receive a kidney transplant. Therefore, we aimed in this study to assess the prevalence of pain among ESKD patients on HD, as well as to explore the factors that were associated with this complaint.

METHODS

We conducted a multicenter cross-sectional study in the West Bank, Palestine, between August and November 2018. We used questionnaire-based direct interviews with subjects. After reviewing previous studies in the field, we developed our questionnaire and included items on patients' social, demographic, and clinical characteristics, including dialysis-related data. It also contained the Brief Pain Inventory (BPI) to assess different aspects of pain symptoms. A convenience sampling technique was used to collect data.

RESULTS

Of the 300 participants, 66.3 % reported having chronic pain. HD sessions themselves were the most commonly cited cause for pain (21.6 %). The most commonly cited site of pain was the upper and lower limbs (37.3 %). Paracetamol was the most frequently used pharmacotherapy for pain alleviation. Multiple regression analysis showed that BMI (p = 0.018), gender (p = 0.023), and the number of comorbidities (p < 0.001) were independently associated with pain severity score.

CONCLUSIONS

Pain is a highly prevalent symptom among HD patients in Palestine. Subpopulations with higher pain severity include females, patients with higher BMI, and those with multiple comorbidities. Healthcare providers should routinely assess pain in HD patients as it is considered a significant concern. This would involve pain assessment and development of a treatment plan to improve clinical outcomes. The nephrology associations should also push for pain management in HD patients as a clinical and research priority to improve pain-related disability.

The Reliability and Agreement of the Fibromyalgia Survey Questionnaire in an Italian Sample of Obese Patients

The Fibromyalgia Survey Questionnaire (FSQ) was self-administered by a sample of 207 Italian individuals with obesity to screen for fibromyalgia (FM). We aimed to investigate the inter-rater reliability and the agreement in the detection of FM symptomatology between the self-administered FSQ and the clinical interview conducted by a rheumatologist. All the patients were divided randomly into two groups (group A and group B): a rheumatologist first interviewed patients of group A and after 48 h, the patients completed the self-report FSQ. Patients of group B first completed the FSQ and 48 h later were interviewed by a rheumatologist. The agreement between the measurements was good with the Bland-Altman analysis showing low bias scores for the two subscales of the FSQ. Results showed that 33% of the sample satisfied the criteria for a diagnosis of fibromyalgia. The FSQ is a self-reporting measure that showed substantial reliability providing fast screening for FM symptomatology.

Chronic pain and weight regain in a lifestyle modification trial

Objective

Obesity and chronic pain often co‐occur and exert bidirectional influences on one another. How patients with obesity and chronic pain respond to weight loss treatments, however, remains unclear. This study evaluated body weight, physical activity, and diet outcomes in participants with and without chronic pain in a 2‐year behavioral weight loss trial.

Methods

An analytical cohort of 397 adults was assembled from a Midwestern healthcare system that participated in the larger trial. Participants with chronic pain 1 year prior to, or during, the trial were identified using a validated medical records algorithm. Mixed models were used to estimate changes in outcomes over 24 months.

Results

One‐third of participants (n = 130) had chronic pain. After adjustment for age, sex, body mass index, and trial arm, weight loss was similar in both groups at 6‐months (−7.0 ± 0.8 kg with chronic pain vs. −7.7 ± 0.6 kg without). Participants with chronic pain had significantly less weight loss at 24‐months relative to those without (−3.6 ± 0.5 vs. −5.2 ± 0.4 kg; p = 0.007). Physical activity, screen time, dietary fat, fruit/vegetable consumption, and sugar‐sweetened beverage intake improved similarly in both groups over time.

Conclusions

Participants with chronic pain lost ∼33% less weight over 2 years, which was driven by greater weight regain after the first 6 months. Future research should test tailored weight loss maintenance strategies for individuals with chronic pain.

Interrelationship of Neurogenic Obesity and Chronic Neuropathic Pain in Persons With Spinal Cord Injury

The prevalence of obesity and of neuropathic pain are both estimated at above 50% in the population of people with chronic spinal cord injury (SCI). These secondary consequences of SCI have significant negative impact on physical functioning, activities of daily living, and quality of life. Investigations of relationships between weight or body composition and chronic neuropathic pain in people with SCI are lacking, but investigations in non-SCI cohorts suggest an association between obesity and the presence and severity of neuropathic pain conditions. In the present article, we present a review of the literature linking obesity and neuropathic pain and summarize findings suggesting that metabolic syndrome and chronic, systemic inflammation due to excess adiposity increase the risk for neuropathic pain after an SCI.

A Mobile Health Behavior Intervention to Reduce Pain and Improve Health in Older Adults With Obesity and Chronic Pain: The MORPH Pilot Trial

Chronic, multisite pain is a common phenomenon in aging and is associated with a host of negative health outcomes. It is a complex and multifaceted condition that may be exacerbated by weight gain and long periods of inactivity. Unfortunately, older adults suffering from chronic pain have unique barriers limiting access to center-based behavior change interventions. The MORPH study first adapted and iteratively refined an evidence-based group-mediated intervention for delivery in the home via mHealth tools (a smartphone app, teleconferencing software, wearable activity monitor, smart weight scale). This was followed by a pilot randomized controlled trial (RCT) meant to assess feasibility of the MORPH intervention, and to examine initial effects on physical function, pain, weight, and sedentary behavior. We recruited low-active and obese older adults with multisite pain to partake in a series of N-of-1 refinement studies (N = 5 total) or a 12-week pilot RCT delivered largely in the home (N = 28 assigned to active intervention or wait-list control). The refinement phase identified several key technological (e.g., selection of a new smart weight scale) and user interface (e.g., clarification of in-app phrasing) modifications that were made before initiating the RCT phase. Analyses of covariance, controlling for baseline values, sex, and age indicated effects favoring the intervention across all domains of interest: there was a substantially clinically meaningful difference in short physical performance battery scores (0.63 points, η² = 0.08), a moderate-to-large difference in PROMIS pain intensity scores (5.52 points, η² = 0.12), a large difference in body weight (2.90 kg, η² = 0.207), and a moderate effect on adjusted ActivPAL-assessed sedentary time (64.90 min, η² = 0.07) with a small effect on steps (297.7 steps, η² = 0.01). These results suggest a largely-home delivered movement and weight loss program for older adults with pain is feasible and recommendations are provided for future programs of this nature.

Clinical Trial Registration:ClinicalTrials.gov, Identifier: NCT03377634.

The Role of Anxiety Sensitivity in terms of Weight-related Impairment and Fatigue Severity among Adults with Obesity and Chronic Low Back Pain

BACKGROUND

Obesity and chronic low back pain often co-occur and are associated with psychosocial and physical impairments such as weight-related impairment and fatigue. Yet, there is little understanding of psychological factors that may be associated with weight-related impairment and fatigue (a psychosocial factor) among this vulnerable population.

METHODS

Thus, the current study examined the role of anxiety sensitivity as it relates to self-reported weight-related impairment and fatigue severity among persons with obesity and chronic low back pain. Participants included a nationally representative sample of adults (N = 616) with co-occurring obesity and chronic low back pain (77.3% female, M age = 45.9 years, SD = 11.53).

RESULTS

Results revealed that anxiety sensitivity was associated with greater levels of weight-related impairment and fatigue severity after controlling for age, sex, body mass index (BMI), pain interference, and perceived general health.

CONCLUSIONS

The findings suggest that anxiety sensitivity may be a mechanistic target for better understanding and addressing weight-related impairment and fatigue severity among individuals with obesity and chronic low back pain.

Obesity with radiological changes or depression was associated with worse knee outcome in general population: a cluster analysis in the Nagahama study

Background

In knee osteoarthritis (OA), pain is the most frequent and dominant symptom. However, which factors other than radiological changes contribute to the symptoms is unresolved. The aims of this study were to identify factors affecting knee pain from various variables with radiological changes taken into count and exploratively examine what subgroups or phenotype could be identified by cluster analysis using the identified knee pain factors.

Methods

Patients 60 years or older who underwent radiographic evaluation were included in this cross-sectional study, and those subjects who completed a questionnaire about knee symptoms without missing data were eligible for analysis. Multiple regression analysis was used to examine the associations between selected variables and The Japanese Knee Osteoarthritis Measure (JKOM) pain score. We grouped the subjects by cluster analysis using identified variables.

Results

Two thousand five hundred forty-two subjects were included in the full set of analyses. Age, body mass index (BMI), radiological grade, bone mineral density (BMD), and high-sensitivity C-reactive protein (hs-CRP) showed a statistically significant correlation with radiological showing the strongest value. For dichotomous variable, presence of depression showed a statistically significant result. We used BMI, radiological grade, BMD, hs-CRP, and presence of depression as a variable for cluster analysis and identified six subgroups: (1) minimal joint disease subgroup, (2) male and high BMD subgroup, (3) high CRP subgroup, (4) severe radiological OA subgroup, (5) depressive subgroup, and (6) moderate radiological OA with high BMI subgroup, showing the worst knee outcome.

Conclusion

This study identified the factors affecting knee pain other than radiological changes and identified six subgroups of knee outcome in the general population. The results showed that obesity with radiological changes or depression was associated with worse knee outcome.

Dietary Interventions Are Beneficial for Patients with Chronic Pain: A Systematic Review with Meta-Analysis

Background

The standard Western diet is high in processed hyperpalatable foods that displace nutrient-dense whole foods, leading to inflammation and oxidative stress. There is limited research on how these adverse metabolic drivers may be associated with maladaptive neuroplasticity seen in chronic pain and whether this could be attenuated by a targeted nutritional approach. The aim of this study was to review the evidence for whole-food dietary interventions in chronic pain management.

Method

A structured search of eight databases was performed up to December 2019. Two independent reviewers screened studies and evaluated risk of bias by using the National Institutes of Health assessment tool for controlled or pre–post studies and the Joanna Briggs checklist for case reports. A meta-analysis was performed in Review Manager.

Results

Forty-three studies reporting on 48 chronic pain groups receiving a whole-food dietary intervention were identified. These included elimination protocols (n = 11), vegetarian/vegan diets (n = 11), single-food changes (n = 11), calorie/macronutrient restriction (n = 8), an omega-3 focus (n = 5), and Mediterranean diets (n = 2). A visual analog scale was the most commonly reported pain outcome measure, with 17 groups reporting a clinically objective improvement (a two-point or 33% reduction on the visual analog scale). Twenty-seven studies reported significant improvement on secondary metabolic measures. Twenty-five groups were included in a meta-analysis that showed a significant finding for the effect of diet on pain reduction when grouped by diet type or chronic pain type.

Conclusion

There is an overall positive effect of whole-food diets on pain, with no single diet standing out in effectiveness. This suggests that commonalities among approaches (e.g., diet quality, nutrient density, weight loss) may all be involved in modulating pain physiology. Further research linking how diet can modulate physiology related to pain (such as inflammation, oxidative stress, and nervous system excitability) is required.

Low-volume high-intensity interval training improves cardiometabolic health, work ability and well-being in severely obese individuals: a randomized-controlled trial sub-study

BACKGROUND

Obesity is associated with impaired health and lower work ability. Increased physical activity is a cornerstone in the treatment of obesity and related risk factors. Recently, high-intensity interval training (HIIT) has emerged as a popular exercise option. However, data regarding the effects on cardiometabolic health, perceived work ability and well-being in severely obese individuals are lacking.

METHODS

Sixty-five obese individuals with sedentary occupation (48.7 ± 9.9 years, BMI: 39.6 ± 7.1 kg/m2) were randomly allocated to an extremely time-efficient HIIT (5 × 1 min at 80-95% maximal heart rate on cycle ergometers, 2×/week for 12 weeks) or an inactive control group (CON). Both groups received nutritional counseling to support weight loss. Primary outcome was maximal oxygen uptake (VO2max), secondary outcomes were cardiometabolic risk indices, body composition, work ability index (WAI), quality of life (QoL, EQ-5D-5L-questionnaire) and perceived stress (PSQ-questionnaire).

RESULTS

Mean body weight reduction was 5.3 kg [95% confidence interval (95% CI) - 7.3 to - 3.3 kg] in the HIIT group (P < 0.001) and 3.7 kg (95% CI - 5.3 to - 2.1 kg) in CON (P < 0.001), respectively. Only the HIIT group showed significant (P < 0.001) changes in VO2max [+ 3.5 mL/kg/min (95% CI 2.5 to 4.6 mL/kg/min)], waist circumference [-7.5 cm (95% CI - 9.8 to - 5.1 kg)], mean arterial blood pressure [- 11 mmHg (95% CI - 14 to - 8 mmHg)], WAI [+ 3.0 points (95% CI 1.7 to 4.3 points)] and QoL [+ 10% (95% CI 5 to 16%)]. In CON, none of these parameters improved significantly.

CONCLUSIONS

Low-volume HIIT may induce significant improvements in cardiometabolic health, especially VO2max, WAI and well-being in obese individuals after only 12 weeks. Our results underpin the wide range of benefits on health and subjective measures through exercise that go well beyond simple weight loss through dietary restriction alone.

TRIAL REGISTRATION

ClinicalTrials.gov Id: NCT03306069. Registered 10 October 2017, https://clinicaltrials.gov/ct2/show/NCT03306069 .

The sad weekend: A perilous North American tradition

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Long-term consumption of poor-quality diet prolonged recovery.

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Mice with only weekend access to poor-quality diet recovered similarly to those with constant access.

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Diet composition significantly changed abundance and diversity of bacterial groups in the gut.

Obesity is a global concern and affects millions of Americans who consume poor-quality diets. Diets directly affect the gut microbiota, which can have subsequent effects on inflammation and contribute to other chronic states. Previously we have shown that a Standard American Diet (SAD) increased immune cell activation and prolonged recovery and that a beneficial diet could reduce these negative effects. Here, male and female mice were given access to regular chow (REG), SAD, our Anti-Inflammatory Diet (AID) or a combination of SAD and AID. This latter group was modeled on the commonplace dietary pattern of healthy eating during the week (AID: Monday-Friday) and relaxed eating patterns on the weekend (SAD: Saturday-Sunday). After 14 weeks of diet consumption and an inflammatory injury, we found that the SAD prolonged and the AID promoted recovery. However, recovery was significantly delayed in those mice consuming the AID-SAD, regardless of weekly healthy diet access. In addition, fecal samples taken during the study revealed dramatic differences in microbial community composition, relative abundance of abundant bacterial phyla and alpha diversity. These data confirm the impact of diet on gut microbiota and suggest a relation between abundance of specific bacterial taxa and susceptibility to prolonged recovery from injury.

Excess Body Mass and Leisure Time Physical Activity in the Incidence and Persistence of Chronic Pain

OBJECTIVE

To estimate the effects of excess body mass and leisure time physical activity on the incidence and persistence of chronic pain.

DESIGN

A prospective cohort study.

METHODS

As a part of the Finnish Helsinki Health Study, we included three cohorts of employees of the City of Helsinki (18,562 observations) and defined incident chronic pain as having pain in any part of the body for more than three months at follow-up in participants without chronic pain at baseline (N = 13,029 observations). Persistent chronic pain was defined as having pain for more than three months at both baseline and follow-up (N = 5,533 observations).

RESULTS

Overweight (adjusted odds ratio [OR] = 1.18, 95% confidence interval [CI] = 1.06-1.31) and obesity (OR = 1.65, 95% CI = 1.45-1.88) increased the incidence of chronic pain. Moreover, overweight (OR = 1.16, 95% CI = 1.02-1.32) and obesity (OR = 1.48, 95% CI = 1.26-1.74) increased the risk of persistent chronic pain. Vigorous leisure time physical activity reduced the incidence of chronic pain (OR = 0.85, 95% CI = 0.75-0.96). Physical activity did not influence the risk of persistent chronic pain. Furthermore, overweight/obesity modified the effect of leisure time physical activity on incident chronic pain. Inactive overweight or obese participants were at the highest risk of chronic pain (OR = 1.71, 95% CI = 1.40-2.09), while the OR dropped to 1.44 (95% CI = 1.19-1.75) in moderately active overweight or obese participants and to 1.20 (95% CI = 0.97-1.47) in highly active overweight or obese participants.

CONCLUSIONS

Obesity not only increases the risk of developing chronic pain, but also increases the risk of persistent pain, while leisure time physical activity reduces the risk of developing chronic pain.

Obesity Trends Amongst Hospitalized Patients with Spinal Cord Stimulator Implants

INTRODUCTION

Chronic pain remains an important public health problem as it continues to increase healthcare-related cost. Comorbidities like obesity have been associated with efficacy of spinal cord stimulator (SCS) therapy and worse outcomes. The goal of this study is to investigate the trends of obesity amongst hospitalized patients with SCS therapy as well as healthcare utilization outcomes.

METHODS

Using the International Classification of Diseases (ICD) ninth and tenth procedure and diagnosis code, we investigated the National Inpatient Sample (NIS) for patients with SCS implants between 2011 and 2015. Patients received a diagnosis of obesity based on the following categories: class I, II and III obesity. Age, gender, and comorbid conditions of patients with obesity were matched 1:1 on propensity score to those without obesity diagnosis. Our primary outcome was defined as trend of obesity diagnosis. Our secondary outcome, healthcare utilization, included in-hospital cost, length of stay, and discharge location.

RESULTS

Between 2011 and 2015, a total of 3893 patients with SCS implants were identified (average age 56 ± 15 years, 58% female, 0.70 ± 1.1 Charlson Comorbidity Index, CCI). Of this cohort, 640 patients were identified as obese. The proportion of patients with obesity diagnosis increased significantly from 13.75% in 2011 to 19.36% in 2015 (p < 0.001). After 1:1 matching on propensity score, 597 patients with obesity were successfully matched to 597 patients without obesity. The total hospital cost for SCS patients with obesity (median $104,845, IQR $74,648-144,292) was not significantly different from patients without obesity diagnosis (median $111,092, IQR $68,990-145,459) (p = 0.161).

CONCLUSIONS

The data from our study suggests that there is an increasing rate of obesity diagnosis amongst patients with SCS therapy. However, there was no difference in healthcare utilization between patients with and without obesity. Additional studies may provide more insight into our findings.

Effects on body weight, eating behavior, and quality of life of a low-energy diet combined with behavioral group treatment of persons with class II or III obesity: A 2-year pilot study

Objective

Obesity is associated with reduced health‐related quality of life (HRQoL). Outcomes of nonsurgical weight loss treatment on HRQoL are inconsistent and it is unclear how much weight reduction, or what type of treatment, is required for significant improvements. This study aimed to evaluate the effects of a lifestyle intervention program on weight, eating behaviors, and HRQoL, and to describe participants' experiences of treatment.

Methods

This 2‐year intervention trial in persons with class II or III obesity comprised a 3‐month liquid low‐energy diet (880 kcal/d) followed by a 3‐month reintroduction to regular foods, combined with behavioral group treatment.

Results

Fifty‐five participants (73% women) were included, mean (SD) age 43.2 (12.4) years, and mean body mass index 42.0 (6.0) kg/m². Mean weight loss at 6, 12, and 24 months was 18.9%, 13.7%, and 7.2%, respectively. Short‐ and long‐term effects on eating behavior were favorable. Twelve of 14 HRQoL domains were improved at 6 months, compared to eight domains at 12 months. After 24 months, 2 of 14 domains, physical and psychosocial functioning, were improved. The treatment program was well accepted by the participants.

Conclusions

Substantial weight loss after 6 months was associated with extensive improvements in HRQoL, comprising the physical, psychosocial, and mental domains. Significant weight regain was observed between 6 and 24 months follow‐up. Modest weight loss after 24 months was associated with moderate improvement in physical functioning and large improvement in psychosocial functioning. The effect on psychosocial functioning is most likely related to both weight loss and behavioral treatment.

Analgesic efficacy of ketamine and magnesium after laparoscopic sleeve gastrectomy: A randomized, double-blind, placebo-controlled trial

Background Ketamine and magnesium are antagonists of the N-methyl-d-aspartate receptor, and are valuable adjuvants for multimodal analgesia and opioid sparing. Data are limited regarding the opioid sparing efficacy of the combined intraoperative application of these agents in laparoscopic bariatric surgery. The objective of this study was to compare the postoperative opioid sparing properties of a single intraoperative dose of ketamine versus a combination of single doses of ketamine and magnesium after laparoscopic gastric sleeve resection in bariatric patients. Methods One hundred and twenty- six patients were randomly assigned to receive single boluses of ketamine alone 0.5 mg kg^-1 IV (ketamine group); combined ketamine bolus of 0.5 mg kg^-1 IV and magnesium 2 g IV (ketamine and magnesium group); or placebo. Opioid consumption at 24 h (in morphine equivalents); pain at rest; postoperative nausea and vomiting impact score; sedation scores; and trends of transcutaneous carbon-di-oxide values were analysed. Results The median (inter-quartile range [range]) morphine consumption at 24 h were 32 (24-47 [4.8-91]) mg in the ketamine group, 37 (18-53 [1-144]) mg in the ketamine and magnesium group, and 26 (21-36 [5-89]) mg in the control group and were not significantly different between the groups. There were no differences for all other outcomes examined. Conclusion Combined single intraoperative bolus doses of ketamine and magnesium did not result in postoperative opioid sparing after laparoscopic gastric sleeve resection.

Effects of a Fat-Rich Diet on the Spontaneous Release of Acetylcholine in the Neuromuscular Junction of Mice

Western societies are facing a clear increase in the rate of obesity and overweight which are responsible for musculoskeletal pain. Some of the substances described in the environment of myofascial trigger points (MTrPs) are the same as those found in the skeletal muscle of obese people, such as cytokines. Furthermore, elevated neuromuscular neurotransmission has been associated with MTrPs. The main objective of this study is to assess whether obesity or overweight may be a facilitator of myofascial pain. The experiments were performed on male Swiss mice. One experimental group was given a typical “cafeteria” diet and another group a commercial high-fat diet for six weeks. Intramuscular adipocytes were assessed with Sudan III. The functional study was performed with electromyographic recording to determine the plaque noise and intracellular recording of miniature endplate potentials (MEPPs). The intake of a cafeteria diet showed the presence of more adipocytes in muscle tissue, but not with the fat-supplemented diet. Both experimental groups showed an increase in the plaque noise and an increase in the frequency of MEPPs that lasted several weeks after interrupting diets. In summary, the supply of a hypercaloric diet for six weeks in mice increases spontaneous neurotransmission, thus facilitating the development of MTrPs.

Chronic Opioid Use and Risk of Cancer in Patients with Chronic Noncancer Pain: A Nationwide Historical Cohort Study

BACKGROUND

To investigate whether chronic opioid therapy is associated with a higher risk of cancer among noncancer patients with chronic pain.

METHODS

A population-based historical cohort study of the South Korean adult population was conducted using data from the National Health Insurance Service. We included patients registered with a diagnostic code of M00-M99 (musculoskeletal system and connective tissue diseases) according to the International Classification of Diseases, 10th revision, in 2010. Patients prescribed a continuous supply of any opioid drug for ≥90 days were defined as chronic opioid users.

RESULTS

A total of 351,701 patients were analyzed. Among them, 25,153 (7.2%) were chronic opioid users. Using a multivariate time-dependent Cox regression model, the risk of cancer in chronic opioid users was 1.20-fold higher than that in controls [HR, 1.20; 95% confidence interval (CI), 1.15-1.25; P < 0.001]. On subgroup analysis according to opioid potency, the cancer risk in chronic weak and strong opioid users was 1.18-fold (HR, 1.18; 95% CI, 1.13-1.23; P < 0.001) and 1.32-fold (HR, 1.32; 95% CI, 1.10-1.59; P = 0.003) higher than that in controls, respectively.

CONCLUSIONS

Chronic opioid therapy was associated with an increased risk of cancer among noncancer patients with chronic pain. This association was more evident in chronic strong opioid users. However, as unmeasured and potential confounders may have affected the results, the relationship between chronic opioid use and cancer risk should be evaluated with caution.

IMPACT

Chronic opioid therapy was associated with an increased risk of cancer among noncancer patients.

The Effect of Body Mass Index Class on Patient-Reported Health-Related Quality of Life Before and After Total Hip Arthroplasty for Osteoarthritis: Registry-Based Cohort Study of 64,055 Patients

BACKGROUND

Overweight status and obesity represent a global epidemic, with serious consequences at the individual and community levels. The number of total hip arthroplasties (THAs) among overweight and obese patients is expected to rise. Increasing body mass index (BMI) has been associated with a higher risk of mortality and reoperation and lower implant survival. The evaluation of perioperative health-related quality of life (HRQoL) has recently gained importance because of its direct relation to, and impact on, patients' physical, mental, and social well-being as well as health-service utilization. We sought to evaluate the influence of BMI class on HRQoL preoperatively and at 1 year following THA in a register-based cohort study.

METHODS

This observational cohort study was designed and conducted on the basis of registry data derived from the Swedish Hip Arthroplasty Register (SHAR) and included 64,055 primary THAs registered between January 1, 2008, and December 31, 2015. Patients' baseline preoperative and 1-year postoperative EuroQol-5 Dimension-3 Level (EQ-5D-3L) responses were documented by the treating department and reported to the SHAR through the patient-reported outcome measures program. The EQ-5D-3L includes a visual analogue scale (EQ VAS), which measures the patient's overall health status.

RESULTS

At 1 year of follow-up, all BMI classes showed significant and clinically relevant improvements in all HRQoL measures compared with preoperative assessment (p < 0.05). Patients reported improved perception of current overall health status for the EQ VAS. Underweight, overweight, and all obesity classes showed increasingly worse 1-year HRQoL compared with normal weight, both with unadjusted and adjusted calculations.

CONCLUSIONS

In this study, we found that all BMI classes had significant improvement in HRQoL at 1 year following THA. Patients who were underweight, overweight, or obese (classes I to III), compared with those of normal weight, reported worse hip pain and EQ-5D-3L and EQ VAS responses prior to THA and at 1 year postoperatively. These results can assist both health-care providers and patients in establishing reasonable expectations about THA outcomes.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Episodic future thinking reduces chronic pain severity: A proof of concept study

BACKGROUND

Chronic pain is a major public health challenge in the United States and around the world. Current treatments including opioid analgesics and cognitive behavioral therapy possess harmful side effects or limited efficacy, respectively. Chronic pain is associated with a variety of unhealthy behaviors including opioid misuse. Moreover, individuals who suffer from chronic pain exhibit excessive discounting of delayed rewards, suggesting a constricted temporal window of valuation. Reductions in the excessive discounting of delayed rewards has been achieved with Episodic Future Thinking (EFT; vividly imagining realistic future events). EFT has also been associated with reductions in a variety of unhealthy behaviors. In this study, the effects of EFT on delay discounting and levels of pain were investigated in individuals reporting chronic pain.

METHODS

Individuals reporting chronic pain (N = 250; 42.4 % female) were recruited through the Amazon Mechanical Turk platform. Measures of delay discounting and pain were collected at baseline and again after randomization to EFT (N = 128) or Control Episodic Thinking (CET) (N = 122).

RESULTS

EFT significantly reduced delay discounting relative to baseline (p < 0.001) and EFT reduced pain scores in a baseline dependent manner (p = 0.001) when compared to CET; that is, those with the greatest reports of pain experienced the greatest reduction. Furthermore the reduction in delay discounting fully mediated the reduction in pain.

CONCLUSIONS

These findings suggest that Episodic Future Thinking, by widening the temporal window, may reduce pain in those reporting chronic pain and therefore represents a potential novel therapeutic.

Detoxification Enhanced Lifestyle Intervention Targeting Endotoxemia (DELITE) in the Setting of Obesity and Pain: Results of a Pilot Group Intervention

BACKGROUND

Obesity is a complex multifactorial disorder affecting a growing proportion of the population. While therapeutic lifestyle change (TLC) is foundational, results of interventional programs are often inconsistent. Factors related to systemic inflammation, toxin load and endotoxemia have been postulated to play a contributory role. This pilot study sought to evaluate the role of TLC with enhanced laboratory evaluation and interventions to address these emerging therapeutic targets.

METHODS

Twelve participants with a body mass index (BMI) greater than 30 (or 27 with metabolic co-morbidities) were recruited from an outpatient clinic for participation with a primary outcome of pre/post changes in body composition. Participants completed a 12-week program involving weekly group and individualized dietary, exercise, and behavioral support, supplemented with a commercial, 30-day dietary detoxification intervention and ongoing nutritional counseling. All participants completed baseline and post-intervention evaluation including metabolic, toxin load, endotoxin, body composition and functional fitness profiles.

RESULTS

After 12-weeks, participants as a group significantly improved body composition parameters including BMI, body fat, fat mass, and waist and hip circumference (P < .01). Significant improvement in several secondary outcomes including levels of lipopolysaccharide, zonulin and leptin were noted. Additionally, results demonstrate substantial improvements in pain, pain interference and functional fitness. Upon completion, all participants rated the program favorably with a high likelihood of continuing or recommending participation to others.

CONCLUSIONS

Obesity remains a challenging and often refractory clinical scenario with emerging evidence indicating the potential role of systemic inflammation, toxin load and endotoxemia. A group therapeutic lifestyle change program enhanced with a detoxification component is feasible and may provide a promising intervention for achieving weight loss while also addressing functional and pain related co-morbidities. Future randomized trials evaluating the components of such a program are needed to better delineate the role of specific interventions in the complex setting of obesity.

Facing obesity in pain rehabilitation clinics: Profiles of physical activity in patients with chronic pain and obesity-A study from the Swedish Quality Registry for Pain Rehabilitation (SQRP)

Background

The obesity epidemic has influenced pain rehabilitation clinics. To date, little is known about baseline level of physical activity (PA) in patients referred to pain rehabilitation clinics. We aimed to investigate the PA levels of patients referred to pain rehabilitation clinics and to evaluate the effect of excess weight on PA level.

Methods and findings

Data were obtained from the Swedish Quality Registry for Pain Rehabilitation between 2016 and 2017. These data included PA time (everyday PA and physical exercise per week), Body Mass Index (BMI), sociodemographic factors, chronic pain and psychological aspects (e.g., pain intensity, depressive and anxiety symptoms and insomnia problems). Insufficient PA was defined as less than 150 minutes per week. We performed logistic regressions as well as orthogonal partial least square regression to estimate the effects of excess weight on PA. Over one-fourth of the patients were classified as obese (BMI ≥30 kg/m², 871/3110, 25.3%) and nearly one-third of these patients were classified as severely obese (BMI ≥35 kg/m², 242/871, 27.8%). Time estimations for physical exercise varied among the BMI groups, but patients in the higher BMI category were more likely to spend less time on everyday PA. Compared to normal weight, mild obesity [odds ratio (OR) 0.65, 95% confidence interval (CI) 0.53–0.81] and severe obesity (OR 0.56, 95% CI 0.42–0.74) were associated with less PA. Mild obese patients had an elevated risk of 65% and severe obese patients had an elevated risk of 96% for insufficient PA. Increased pain intensity was positively related to insufficient PA (OR 1.17, 95% CI 1.06–1.29) among the obese patients.

Conclusion

Having low PA is very common for patients referred to pain rehabilitation clinics, especially for those with comorbid obesity. As a first step to increase PA, obese patients need to be encouraged to increase the intensity and amount of less painful daily PA.

Chronic non-cancer pain management in primary care

Chronic non-cancer pain is a common, often undiagnosed condition in primary care across the world, with prevalence rates between 20% and 40%. To effectively address this problem, the primary care practitioner needs to have an organised, comprehensive approach to diagnosing and managing these patients within a biopsychosocial framework, in collaboration with members of the interdisciplinary team. The aim of this article is to provide the primary care practitioner with up to date information on the management of chronic pain. A case study is introduced to raise awareness of some of the complexities of dealing with the problem. A series of key questions are raised that address the various levels of complexity. Current evidence is used to guide the reader through these questions, covering a wide area of pain research as it pertains to primary care. The article concludes with five practice points that link the literature to clinical practice.

The effect of intermittent diet and/or physical therapy in patients with chronic low back pain: A single-blinded randomized controlled trial

BACKGROUND AND PURPOSE

This study aimed to investigate the effect of intermittent diet and/or physical therapy in patients with chronic low back pain.

MATERIALS AND METHODS

Sixty sedentary volunteers with chronic low back pain participated in the study. Body weight and body mass index (BMI) were measured. Pain severity was assessed using Visual Analogue Scale (VAS) and Leeds Assessment of Neuropathic Symptoms and Signs (LANSS), while assessment of disability was done using Barthel Index (BI).

RESULTS

The weight and BMI were reduced after treatment with diet only and diet plus physical therapy (p < 0.001). The pain severity was reduced in all the treated groups (p < 0.001), while BI was increased in the group treated with only physical therapy (p < 0.001).

CONCLUSION

The present study indicated that intermittent diet and/or physical therapy are beneficial to patients with chronic low back pain in terms of pain sensation and daily activities.

Increases in BMI and chronic pain for US adults in midlife, 1992 to 2016

Recent unprecedented increases in mortality and morbidity during midlife are often ascribed to rising despair in the US population. An alternative and less often examined explanation is that these trends reflect, at least in part, the lagged effects of the obesity epidemic. Adults in midlife today are more likely to live with obesity and have a greater cumulative exposure to excess adiposity during their lifetime than any previous generation. Prior work has demonstrated a link between obesity and mortality risk at midlife, but the mechanisms remain unclear. Pain may represent one important pathway linking obesity to mortality trends. Pain is a debilitating condition that has increased significantly over recent decades and is associated with both morbidity and mortality, including suicide and opioid-related mortality. Evidence suggests obesity and pain may be linked, but there is little evidence of an association at the population level. In this paper, we examine to what extent increases in overweight and obesity explain the rising trends in chronic pain observed among middle-aged adults in the US from 1992 to 2016. We assess trends in both mild/moderate nonlimiting pain and severe and/or limiting pain. In doing so, we draw attention to one mechanism through which overweight/obesity may have contributed to recent population health trends. Our analysis found that increases in BMI from 1992 to 2016 may account for up to 20% of the upward trend in mild/moderate nonlimiting pain and 32% of the trend in severe and/or limiting pain for women, and 10% and 19% of the trends respectively for men.

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We study the contribution of overweight and obesity to recent trends in pain among middle-aged adults.

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Overweight and obesity accounted for 32.1% of increases in severe or limiting pain among women and 19.0% among men.

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Overweight and obesity explained a larger share of the increase in severe than mild/moderate pain.

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The study highlights the importance of obesity prevention to decrease the prevalence of pain.

The role of physical pain in global functioning of people with serious mental illness

While people with serious mental illness (SMI) endorse clinical pain at rates on par or exceeding those in the general population, the association between pain and functioning remains unclear. In this paper we present data on the cross-sectional association between clinical pain and global functioning in a large, mixed diagnostic sample of people with SMI. Eight-hundred ninety-eight people diagnosed with bipolar disorder, major depressive disorder, or schizophrenia were administered the Global Assessment Scale and the 12-item Short Form Survey, which includes an assessment of the extent to which the experience of pain interfered with daily activities over the past month. People with major depressive disorder reported higher pain interference than those with schizophrenia and bipolar disorder. The presence of physical health conditions and psychiatric symptoms were also assessed. After controlling for age, gender, psychiatric symptoms, education level, and physical health problems, pain interference in the past month was associated with significantly lower global functioning. The findings suggest that the experience of pain is associated with poorer global functioning across major SMI diagnoses. Moreover, the impact of pain in global functioning appears independent of physical health problems, and thus may warrant routine screening from mental health providers.

The Impact of Obesity on Disease Activity and Treatment Response in Rheumatoid Arthritis

PURPOSE OF THE REVIEW

A growing number of studies have suggested that disease outcomes and response to therapy may be different in patients with rheumatoid arthritis (RA) who are obese. The goal of this review is to examine the most recent literature, with a focus on the impact of obesity on the assessment of disease activity and treatment outcomes in RA.

RECENT FINDINGS

Obesity is common in patients with RA and can have a substantial impact on patient symptoms and outcomes. Obesity is associated with higher rates of chronic pain and opiate use, elevated inflammatory markers, and less reliable physical exam findings, making assessment of disease activity and treatment response more challenging. Despite seemingly worse clinical disease activity, evidence has accumulated demonstrating that obese patients with RA have less inflammation by imaging and lower rates of radiographic progression over time. Whether obesity influences the effectiveness of specific therapies remains controversial. Obesity is very common and is associated with more severe symptoms and higher rates of disability among RA patients. While clinical disease activity is frequently observed to be higher in obese patients with RA, it remains unclear whether poorer treatment response rates in this setting are related to reduced efficacy of therapies or are an artifact of biases in the accurate assessment of the disease.

High prevalence of musculoskeletal pain in individuals with severe obesity: sites, intensity, and associated factors

Background

Musculoskeletal pain is associated with obesity; however, information on factors associated with pain in adults with obesity and severe obesity is limited. The purpose of this study was to assess the prevalence of musculoskeletal pain by site and intensity of pain and associated factors in individuals with severe obesity (body mass index ≥ 35.0 kg/m²).

Methods

Baseline data from the DieTBra Trial study evaluating pain symptoms in nine body regions over the last seven days using the Nordic Questionnaire on Musculoskeletal Symptoms and Numerical Pain Scale. The variables analyzed using multiple Poisson regression with hierarchical analysis were: sociodemographic, lifestyle, food consumption, clinical, and anthropometric, and the outcome was moderate and intense pain.

Results

In 150 participants, there was a high prevalence of ankle and foot pain (68.7%), lower back pain (62.7%), pain in the knees (53.3%) and upper back pain (52.0%), with a predominance of intense pain. Factors associated with pain according to specific sites were: type 2 diabetes with hand/wrist pain; sedentary time with hip pain; insomnia with pain in the hip and knee; edema in the lower limbs with pain in the lower back and ankles/feet; degree of obesity with ankle/foot pain; and percentage of total fat with ankle/foot pain.

Conclusions

There was a high prevalence of pain and intense pain in individuals with severe obesity and an association with clinical variables, the degree of obesity, and sedentary lifestyle.

Physical exercise and chronic pain in university students

Background

Physical inactivity and chronic pain are both major public health concerns worldwide. Although the health benefits of regular physical exercise are well-documented, few large epidemiological studies have investigated the association between specific domains of physical exercise and chronic pain in young adults. We sought to investigate the association between frequency, intensity and duration of physical exercise, and chronic pain.

Methods

Data stem from the SHoT2018-study, a national health survey for higher education in Norway, in which 36,625 fulltime students aged 18–35 years completed all relevant questionnaires. Chronic pain, defined according to the International Classification of Diseases 11th Revision (ICD-11), was assessed with a newly developed hierarchical digital instrument for reporting both distribution and characteristics of pain in predefined body regions. Physical exercise was assessed using three sets of questions, measuring the number of times exercising each week, and the average intensity and the number of hours each time.

Results

The majority (54%) of the students reported chronic pain in at least one location, and the prevalence was especially high among women. The overall pattern was an inverse dose-response association between exercise and chronic pain: the more frequent, harder or longer the physical exercise, the lower the risk of chronic pain. Similar findings were generally also observed for the number of pain locations: frequent exercise was associated with fewer pain locations. Adjusting for demographical, lifestyle factors and depression had little effect on the magnitude of the associations.

Conclusion

Given the many health benefits of regular exercise, there is much to be gained in facilitating college and university students to be more physically active, ideally, thru a joint responsibility between political and educational institutions. Due to the cross-sectional nature of the study, one should be careful to draw a firm conclusion about the direction of causality.

Association Between Low Vitamin D Levels and the Greater Impact of Fibromyalgia

Background

Fibromyalgia (FM) is a clinical syndrome mainly characterized by generalized chronic pain, fatigue, sleep and cognition disorders. The role played by vitamin D in the pathophysiology of painful syndromes is poorly known. Studies assessing the association between vitamin D and FM have presented conflicting results. The aims of the current study were to assess vitamin D levels in FM patients, by comparing them to healthy controls, as well as to analyze their impact on this disease.

Methods

This was a cross-sectional study comprising 43 FM patients (ACR 2010 criteria) and 40 healthy individuals. All participants had their vitamin D levels measured, and FM patients also had their total calcium, albumin, phosphorus and parathyroid hormone (PTH) measured. Clinical variables capable of affecting the results were evaluated and the fibromyalgia impact questionnaire (FIQ) was applied.

Results

There was not statistically significant difference in global mean values of vitamin D between groups. In the total sample, only 4.8% of the individuals had vitamin D deficiency, which corresponded to the deficiency found in the group of patients; in the control, no one had vitamin deficiency; 39.8% had insufficient levels and 55.4% with sufficient levels. The mean serum vitamin D values were similar between the FM and control groups (34.8 ± 12 and 34.7 ± 12.3 ng/mL, respectively; P = 0.806). However, a significant negative correlation was found between vitamin D concentration and FIQ values, that is, patients with the greatest impact of the disease had lower concentrations of vitamin D (P = 0.018).

Conclusion

FM patients did not present higher prevalence of vitamin D deficiency or insufficiency than healthy individuals, although low vitamin D concentrations could indicate more severe disease impacts.

Analysis of genetically independent phenotypes identifies shared genetic factors associated with chronic musculoskeletal pain conditions

Chronic musculoskeletal pain affects all aspects of human life. However, mechanisms of its genetic control remain poorly understood. Genetic studies of pain are complicated by the high complexity and heterogeneity of pain phenotypes. Here, we apply principal component analysis to reduce phenotype heterogeneity of chronic musculoskeletal pain at four locations: the back, neck/shoulder, hip, and knee. Using matrices of genetic covariances, we constructed four genetically independent phenotypes (GIPs) with the leading GIP (GIP1) explaining 78.4% of the genetic variance of the analyzed conditions, and GIP2-4 explain progressively less. We identified and replicated five GIP1-associated loci and one GIP2-associated locus and prioritized the most likely causal genes. For GIP1, we showed enrichment with multiple nervous system-related terms and genetic correlations with anthropometric, sociodemographic, psychiatric/personality traits and osteoarthritis. We suggest that GIP1 represents a biopsychological component of chronic musculoskeletal pain, related to physiological and psychological aspects and reflecting pain perception and processing.

Association of Pain, Severe Pain, and Multisite Pain with the Level of Physical Activity and Sedentary Behavior in Severely Obese Adults: Baseline Data from the DieTBra Trial

The study aimed to assess the prevalence of pain, severe pain, and pain in four or more regions associated with physical activity and sedentary behavior, as well as other associated factors in severely obese adults (Body Mass Index ≥ 35 kg/m2). Baseline data from the DieTBra Trial were analyzed. The outcome variables were pain (yes/no) and pain in four or more sites (yes/no), as identified by the Brazilian version of the Nordic Musculoskeletal Questionnaire, along with the presence of severe pain (yes/no), identified based on the Numerical Pain Rating Scale (≥8). The main independent variables were moderate to vigorous physical activity (MVPA), light physical activity, and sedentary behavior, assessed by triaxial accelerometry. The variables were analyzed using multiple hierarchical Poisson regression. In 150 individuals (men, 14.67%; and women, 85.33%), with a mean age of 39.6 ± 0.7 years, there was a high prevalence of pain (89.33%), severe pain (69.33%), and pain in four or more regions (53.33%). The associated factors were shorter MVPA time with pain (p = 0.010); arthritis/arthrosis (p = 0.007) and the use of muscle relaxants (p = 0.026) with severe pain; and economic class C (p = 0.033), and economic class D (p = 0.003), along with arthritis and arthrosis (p = 0.025) with pain in four or more sites. There were no significant associations between sedentary behavior and any of the three outcomes analyzed. These findings indicate that, in severely obese individuals, shorter MVPA time is associated with a higher prevalence of pain. Future studies on physical activity intervention may contribute to the reduction in the prevalence and severity of pain in adults with severe obesity.

Obesity and Incident Prescription Opioid Use in the U.S., 2000-2015

INTRODUCTION

Prior studies have identified associations between obesity and numerous conditions that increase risks for chronic pain. However, the impact of obesity on prescription opioid use is not well known. This study investigates the association between obesity and incidence of long-term prescription opioid use.

METHODS

Fifteen panels of the Medical Expenditure Panel Survey from 2000 to 2015 were pooled to generate a sample of civilian non-institutionalized adults aged 30-84 years who were prescription opioid-naïve for approximately 9 months. Incident long-term prescription opioid use was defined as reporting use at 2 of 3 interviews during a 15-month follow-up. BMI was reported at baseline. Analyses were completed in 2019.

RESULTS

Among opioid-naïve adults (n=89,629), obesity was strongly associated with incident long-term prescription opioid use. The association increased at progressively higher BMI values, with 24% elevated odds (95% CI=7%, 44%) in adults with overweight (25-29.9 kg/m²) and 158% increased odds (95% CI=106%, 224%) among adults with Class III obesity (40-49.9 kg/m²). These associations grew with higher-dosage opioids. Of the reasons for opioid use, joint pain, back pain, injury, and muscle/nerve pain contributed the most to the excess use observed among adults with obesity. At the population level, 27.0% of incident long-term prescription opioid use (95% CI=19.0%, 34.8%) was attributable to adults having a BMI above normal weight (25-49.9 kg/m²).

CONCLUSIONS

These findings suggest that obesity has contributed to prescription opioid use in the U.S. Future investments in chronic pain reduction may benefit from increased integration with obesity prevention and treatment.

Predictors of pain in general ageing populations: results from a multi-country analysis based on ATHLOS harmonized database

BACKGROUND

Pain is a common symptom, often associated with neurological and musculoskeletal conditions, and experienced especially by females and by older people, and with increasing trends in general populations. Different risk factors for pain have been identified, but generally from studies with limited samples and a limited number of candidate predictors. The aim of this study is to evaluate the predictors of pain from a large set of variables and respondents.

METHODS

We used part of the harmonized dataset of ATHLOS project, selecting studies and waves with a longitudinal course, and in which pain was absent at baseline and with no missing at follow-up. Predictors were selected based on missing distribution and univariable association with pain, and were selected from the following domains: Socio-demographic and economic characteristics, Lifestyle and health behaviours, Health status and functional limitations, Diseases, Physical measures, Cognition, personality and other psychological measures, and Social environment. Hierarchical logistic regression models were then applied to identify significant predictors.

RESULTS

A total of 13,545 subjects were included of whom 5348 (39.5%) developed pain between baseline and the average 5.2 years' follow-up. Baseline risk factors for pain were female gender (OR 1.34), engaging in vigorous exercise (OR 2.51), being obese (OR 1.36) and suffering from the loss of a close person (OR 1.88) whereas follow-up risk factors were low energy levels/fatigue (1.93), difficulties with walking (1.69), self-rated health referred as poor (OR 2.20) or average to moderate (OR 1.57) and presence of sleep problems (1.80).

CONCLUSIONS

Our results showed that 39.5% of respondents developed pain over a five-year follow-up period, that there are proximal and distal risk factors for pain, and that part of them are directly modifiable. Actions aimed at improving sleep, reducing weight among obese people and treating fatigue would positively impact on pain onset, and avoiding vigorous exercise should be advised to people aged 60 or over, in particular if female or obese.

Gene therapy for follistatin mitigates systemic metabolic inflammation and post-traumatic arthritis in high-fat diet-induced obesity

Obesity-associated inflammation and loss of muscle function play critical roles in the development of osteoarthritis (OA); thus, therapies that target muscle tissue may provide novel approaches to restoring metabolic and biomechanical dysfunction associated with obesity. Follistatin (FST), a protein that binds myostatin and activin, may have the potential to enhance muscle formation while inhibiting inflammation. Here, we hypothesized that adeno-associated virus 9 (AAV9) delivery of FST enhances muscle formation and mitigates metabolic inflammation and knee OA caused by a high-fat diet in mice. AAV-mediated FST delivery exhibited decreased obesity-induced inflammatory adipokines and cytokines systemically and in the joint synovial fluid. Regardless of diet, mice receiving FST gene therapy were protected from post-traumatic OA and bone remodeling induced by joint injury. Together, these findings suggest that FST gene therapy may provide a multifactorial therapeutic approach for injury-induced OA and metabolic inflammation in obesity.