Heritability and lifestyle factors in chronic low back pain: Results of the Australian Twin Low Back Pain Study (The AUTBACK study)

Familial effects account for association between chronic pain and past month smoking

BACKGROUND

Smoking is associated with chronic pain, but it is not established whether smoking causes pain or if the link is due to familial effects. One proposed mechanism is that smoking strengthens maladaptive cortico-striatal connectivity, which contributes to pain chronification. We leveraged a twin design to assess direct effects of smoking on pain controlling for familial confounds, and whether cortico-striatal connectivity mediates this association.

METHODS

In a population-based sample of 692 twins (age = 28.83 years), we assessed past-month smoking frequency (n = 132 used in the past month), presence and severity of a current pain episode (n = 179 yes), and resting-state functional connectivity of the nucleus accumbens and medial prefrontal cortex (NAc-mPFC).

RESULTS

Smoking was significantly associated with pain, but the association was not significantly mediated by NAc-mPFC connectivity. In a co-twin control model, smoking predicted which families had more pain but could not distinguish pain between family members. Pain risk was 43% due to additive genetic (A) and 57% due to non-shared environmental (E) influences. Past-month smoking frequency was 71% genetic and 29% non-shared environmental. Smoking and pain significantly correlated phenotypically (r = 0.21, p = 0.001) and genetically (rg = 0.51, p < 0.001), but not environmentally (re = -0.18, p = 0.339).

CONCLUSIONS

Pain and smoking are associated; however, the association appears to reflect shared familial risk factors, such as genetic risk, rather than being causal in nature. The connectivity strength of the reward pathway was not related to concurrent pain and smoking in this sample.

SIGNIFICANCE

Smoking does not appear to directly cause chronic pain; rather, there may be shared biopsychosocial risk factors, including genetic influences, that explain their association. These findings can be integrated into future research to identify shared biological pathways of both chronic pain and smoking behaviours as a way to conceptualize pain chronification.

Educational attainment, family background and the emergence of pain gradients in adulthood

Current studies have indicated that the number of individuals living with pain has risen in recent years, with nearly half of all adults in some countries living with some form of pain. Such trends have prompted researchers to explore differences in pain across different sociodemographic groups, with a dominant focus on educational attainment. However, much of the studies fail to consider the confounding role of early life characteristics, such as family background. Using data on over 400,000 individuals from the UK Biobank, we look at how educational attainment is associated with nine different domains of pain (headache, facial, neck, back, hip, knee, stomach, all over, and no pain). Ultimately, we find that compared to those with no educational credentials, education is associated with anywhere between a 0.1-15% change in the likelihood of reporting pain, depending on pain type and education level, with the greatest change occurring in those with the highest level. Yet, when accounting for family background characteristics in the form of sibling fixed effects, nearly all relationships between education and pain fell by either 50% or were eliminated. We ultimately conclude that failure to consider early life characteristics, such as family background characteristics may lead to inflated estimates of pain, and that future research should delve into early life exposures and their influence on pain in adulthood.

Insight into the Causal Relationship between Gut Microbiota and Back Pain: A Two Sample Bidirectional Mendelian Randomization Study

Observational studies have shown that alterations in gut microbiota composition are associated with low back pain. However, it remains unclear whether the association is causal. To reveal the causal association between gut microbiota and low back pain, a two-sample bidirectional Mendelian randomization (MR) analysis is performed. The inverse variance weighted regression (IVW) is performed as the principal MR analysis. MR-Egger and Weighted Median is further conducted as complementary analysis to validate the robustness of the results. Finally, a reverse MR analysis is performed to evaluate the possibility of reverse causation. The inverse variance weighted (IVW) method suggests that Peptostreptococcaceae (odds ratio [OR] 1.056, 95% confidence interval [CI] [1.015-1.098], P IVW = 0.010), and Lactobacillaceae (OR 1.070, 95% CI [1.026-1.115], P IVW = 0.003) are positively associated with back pain. The Ruminococcaceae (OR 0.923, 95% CI [0.849-0.997], P IVW = 0.033), Butyricicoccus (OR 0.920, 95% CI [0.868 - 0.972], P IVW = 0.002), and Lachnospiraceae (OR 0.948, 95% CI [0.903-0.994], P IVW = 0.022) are negatively associated with back pain. In this study, underlying causal relationships are identified among gut microbiota and low back pain. Notably, further research is needed on the biological mechanisms by which gut microbiota influences low back pain.

Recommending swimming to people with low back pain: A scoping review

BACKGROUND

It is common practice for health professionals to recommend swimming to people with low back pain (LBP) despite limited evidence. The aim of this review was to gain an understanding of the current evidence base supporting the recommendation of swimming to people with LBP.

METHODS

A scoping review was conducted searching five electronic databases, CINAHL, MEDLINE, PEDro, PubMed, and SPORTdiscus using the keywords back pain AND swim*. The studies were grouped by study design and the following uncertainties were considered; the impact of swimming on the spine and LBP, evidence of swimming increasing or reducing the risk of LBP and the use of swimming in LBP rehabilitation programmes.

RESULTS

25 studies met the eligibility criteria; including sixteen observational studies exploring the relationship between swimming and LBP, three biomechanical studies investigating the impact of swimming on the spine, and five interventional studies of which four integrated swimming into a rehabilitation programme and one used swimming to modify lumbar lordosis.

CONCLUSION

The review confirmed there is limited research and only low-level evidence to support the recommendation of swimming to people with LBP. Observational studies make up the greater proportion of research undertaken in the field; the data indicates that swimming is a low-risk form of exercise but not without risk. The findings from biomechanical research suggest that lumbar lordosis does not increase excessively when swimming breaststroke, but certain swimming techniques could negatively impact LBP and interventional trials illustrate that there are various ways to integrate swimming into a rehabilitation programme.

A systematic review of genome-wide association studies for pain, nociception, neuropathy, and pain treatment responses

ABSTRACT

Pain is the leading cause of disability worldwide, imposing an enormous burden on personal health and society. Pain is a multifactorial and multidimensional problem. Currently, there is (some) evidence that genetic factors could partially explain individual susceptibility to pain and interpersonal differences in pain treatment response. To better understand the underlying genetic mechanisms of pain, we systematically reviewed and summarized genome-wide association studies (GWASes) investigating the associations between genetic variants and pain/pain-related phenotypes in humans. We reviewed 57 full-text articles and identified 30 loci reported in more than 1 study. To check whether genes described in this review are associated with (other) pain phenotypes, we searched 2 pain genetic databases, Human Pain Genetics Database and Mouse Pain Genetics Database. Six GWAS-identified genes/loci were also reported in those databases, mainly involved in neurological functions and inflammation. These findings demonstrate an important contribution of genetic factors to the risk of pain and pain-related phenotypes. However, replication studies with consistent phenotype definitions and sufficient statistical power are required to validate these pain-associated genes further. Our review also highlights the need for bioinformatic tools to elucidate the function of identified genes/loci. We believe that a better understanding of the genetic background of pain will shed light on the underlying biological mechanisms of pain and benefit patients by improving the clinical management of pain.

Digital Therapeutics (DTx) Expand Multimodal Treatment Options for Chronic Low Back Pain: The Nexus of Precision Medicine, Patient Education, and Public Health

Digital therapeutics (DTx, software as a medical device) provide personalized treatments for chronic diseases and expand precision medicine beyond pharmacogenomics-based pharmacotherapies. In this perspective article, we describe how DTx for chronic low back pain (CLBP) can be integrated with pharmaceutical drugs (e.g., NSAIDs, opioids), physical therapy (PT), cognitive behavioral therapy (CBT), and patient empowerment. An example of an FDA-authorized DTx for CLBP is RelieVRx, a prescription virtual reality (VR) app that reduces pain severity as an adjunct treatment for moderate to severe low back pain. RelieVRx is an immersive VR system that delivers at-home pain management modalities, including relaxation, self-awareness, pain distraction, guided breathing, and patient education. The mechanism of action of DTx is aligned with recommendations from the American College of Physicians to use non-pharmacological modalities as the first-line therapy for CLBP. Herein, we discuss how DTx can provide multimodal therapy options integrating conventional treatments with exposome-responsive, just-in-time adaptive interventions (JITAI). Given the flexibility of software-based therapies to accommodate diverse digital content, we also suggest that music-induced analgesia can increase the clinical effectiveness of digital interventions for chronic pain. DTx offers opportunities to simultaneously address the chronic pain crisis and opioid epidemic while supporting patients and healthcare providers to improve therapy outcomes.

Back Pain without Disease or Substantial Injury in Children and Adolescents: A Twin Family Study Investigating Genetic Influence and Associations

This twin family study first aimed to investigate the evidence for genetic factors predicting the risk of lifetime prevalence of non-specific low back pain of at least three months duration (LBP (life)) and one-month current prevalence of thoracolumbar back pain (TLBP (current)) using a study of children, adolescents, and their first-degree relatives. Secondly, the study aimed to identify associations between pain in the back with pain in other regions and also with other conditions of interest. Randomly selected families (n = 2479) with child or adolescent twin pairs and their biological parents and first siblings were approached by Twins Research Australia. There were 651 complete twin pairs aged 6-20 years (response 26%). Casewise concordance, correlation, and odds ratios were compared for monozygous (MZ) and dizygous (DZ) pairs to enable inference about the potential existence of genetic vulnerability. Multivariable random effects logistic regression was used to estimate associations between LBP (life) or TLBP (current) as an outcome with the potentially relevant condition as predictors. The MZ pairs were more similar than the DZ pairs for each of the back pain conditions (all p values < 0.02). Both back pain conditions were associated with pain in multiple sites and with primary pain and other conditions using the combined twin and sibling sample (n = 1382). Data were consistent with the existence of genetic influences on the pain measures under the equal environments assumption of the classic twin model and associations with both categories of back pain were consistent with primary pain conditions and syndromes of childhood and adolescence which has research and clinical implications.

Quantitative Global Survey Results of Acute Back Pain Sufferers Across Four Countries

Background

Surveys of back pain sufferers in the United States, China, Russia, and Germany were performed to better understand self-reported causes of acute nonspecific back pain and acute lower back pain among individuals engaging in sports and their preferred treatments.

Methods

In each country, 1000 participants were surveyed (Step 1) to identify a population of nonspecific acute back pain sufferers, understand pain and treatment characteristics, and generate profiles for individuals with long-lasting (≥7 days) acute lower back pain. Subsequently, 200 participants with acute lower back pain episodes (7-21 days) and sports participation were identified in each country and completed surveys (Step 2) about sociodemographic, pain, treatment characteristics, and causes/triggers of long-lasting acute lower back pain episodes.

Results

In the United States, China, Russia, and Germany, respectively, 59%, 49%, 61%, and 63% of respondents reported ≥1 episode of nonspecific acute back pain in the previous 6 months. Average numbers of monthly nonspecific acute back pain episodes in the United States, Russia, Germany, and China were 2.5, 1.8, 1.3, and 0.8, respectively. Prevalence of acute lower back pain associated with sports/leisure activities ranged from 20% (Russia and Germany) to 46% (China). Onset of long-lasting acute lower back pain was between ages 30 and 33 years, limiting usual activities and reducing walking distance in 60% to 85% of respondents across all countries. Acute lower back pain started post-exercise within the first day for ≥75% of respondents. Most popular nonprescription and prescription treatments for acute lower back pain were creams/gels in Russia, creams/gels and oral painkillers in Germany, oral painkillers in the United States, and hot/cold patches in China.

Conclusion

These results help to better understand acute back pain triggers, features, and treatment preferences among sports participants in different countries. Further research is warranted to develop preventative strategies.

Trial Registration

Not applicable.

Brain-specific genes contribute to chronic but not to acute back pain

Introduction

Back pain is the leading cause of disability worldwide. Although most back pain cases are acute, 20% of acute pain patients experience chronic back pain symptoms. It is unclear whether acute pain and chronic pain have similar or distinct underlying genetic mechanisms.

Objectives

To characterize the molecular and cellular pathways contributing to acute and chronic pain states.

Methods

Cross-sectional observational genome-wide association study.

Results

A total of 375,158 individuals from the UK Biobank cohort were included in the discovery of genome-wide association study. Of those, 70,633 (19%) and 32,209 (9%) individuals met the definition of chronic and acute back pain, respectively. A total of 355 single nucleotide polymorphism grouped into 13 loci reached the genome-wide significance threshold (5x10^-8) for chronic back pain, but none for acute. Of these, 7 loci were replicated in the Nord-Trøndelag Health Study (HUNT) cohort (19,760 chronic low back pain cases and 28,674 pain-free controls). Single nucleotide polymorphism heritability was 4.6% (P=1.4x10^-78) for chronic back pain and 0.81% (P=1.4x10-8) for acute back pain. Similar differences in heritability estimates between acute and chronic back pain were found in the HUNT cohort: 3.4% (P=0.0011) and 0.6% (P=0.851), respectively. Pathway analyses, tissue-specific heritability enrichment analyses, and epigenetic characterization suggest a substantial genetic contribution to chronic but not acute back pain from the loci predominantly expressed in the central nervous system.

Conclusion

Chronic back pain is substantially more heritable than acute back pain. This heritability is mostly attributed to genes expressed in the brain.

Association between Fat Distribution and Chronic Low Back Pain among 10,606 Adults: Data from the Korean National Health and Nutrition Examination Survey

Obesity is associated with chronic low back pain (CLBP), but the association between fat distribution and CLBP is unclear. This cross-sectional study evaluated the relationship using the Korean National Health and Nutrition Examination Survey data. A total of 10,606 adults (average age: 45.4, female: 57.1%) were included. We estimated the regional fat distribution, waist circumference, and body fat proportion, compared the values in people with and without CLBP, and stratified the estimates by sex and obesity status using a multivariable linear model. There were no statistically significant differences in the average waist circumference between the people with and without CLBP (p = 0.731) and the average fat proportion between those with and without CLBP (p = 0.731). The average regional fat distribution was significantly higher in the people with CLBP than in those without CLBP, in the upper limbs (11.4%, 95% confidence interval [CI]: [11.3, 11.5] vs. 11.2%, 95% CI: [11.1, 11.3], p < 0.05) and in the lower limbs (31.9%, 95% CI: [31.6, 32.2] vs. 31.4%, 95% CI: [31.2, 31.6], p < 0.01). More obvious among men, fat distribution in the lower limbs is higher than in people without obesity (p < 0.001). People with CLBP tend to have a higher fat distribution in the limbs than those without it and obese people with CLBP would need to reduce the fat in the lower limbs.

Joint Analysis of Genome-Wide Association Data Reveals No Genetic Correlations Between Low Back Pain and Neurodegenerative Diseases

Background: We aimed to explore the genetic correlation and bidirectional causal relationships between low back pain (LBP) and three neurodegenerative diseases, Alzheimer’s disease (AD), Parkinson’s disease (PD), and amyotrophic lateral sclerosis (ALS).

Methods: Summary-level statistics were obtained from genome-wide association studies of LBP (n = 177,860), AD (n = 63,926), PD (n = 482,730), and ALS (n = 80,610). We implemented linkage disequilibrium score regression to calculate heritability estimates and genetic correlations. To investigate possible causal associations between LBP and three neurodegenerative diseases, we also conducted a bidirectional two-sample Mendelian randomization (MR) study. Inverse variance-weighted MR was employed as the primary method to generate overall estimates, whereas complementary approaches and sensitivity analyses were conducted to confirm the consistency and robustness of the findings.

Results: There was no evidence of genetic correlations between LBP and AD (Rg = −0.033, p = 0.766). MR analyses did not support the causal effect of LBP on AD (OR = 1.031; 95% CI, 0.924–1.150; p = 0.590) or the effect of AD on LBP (OR = 0.963; 95% CI, 0.923–1.006; p = 0.090). Likewise, this study failed to identify genetic correlations between LBP and two other neurodegenerative diseases. MR results of the associations of LBP with PD and ALS, and the reverse associations, did not reach Bonferroni-corrected significance.

Conclusion: The study did not support genetic correlations or causations between LBP and three common neurodegenerative diseases, AD, PD, and ALS in the European population.

Sources of Individual Differences in Pain

Pain is an immense clinical and societal challenge, and the key to understanding and treating it is variability. Robust interindividual differences are consistently observed in pain sensitivity, susceptibility to developing painful disorders, and response to analgesic manipulations. This review examines the causes of this variability, including both organismic and environmental sources. Chronic pain development is a textbook example of a gene-environment interaction, requiring both chance initiating events (e.g., trauma, infection) and more immutable risk factors. The focus is on genetic factors, since twin studies have determined that a plurality of the variance likely derives from inherited genetic variants, but sex, age, ethnicity, personality variables, and environmental factors are also considered.

Sex-stratified genome-wide association study of multisite chronic pain in UK Biobank

Chronic pain is highly prevalent worldwide and imparts a significant socioeconomic and public health burden. Factors influencing susceptibility to, and mechanisms of, chronic pain development, are not fully understood, but sex is thought to play a significant role, and chronic pain is more prevalent in women than in men. To investigate sex differences in chronic pain, we carried out a sex-stratified genome-wide association study of Multisite Chronic Pain (MCP), a derived chronic pain phenotype, in UK Biobank on 178,556 men and 209,093 women, as well as investigating sex-specific genetic correlations with a range of psychiatric, autoimmune and anthropometric phenotypes and the relationship between sex-specific polygenic risk scores for MCP and chronic widespread pain. We also assessed whether MCP-associated genes showed expression pattern enrichment across tissues. A total of 123 SNPs at five independent loci were significantly associated with MCP in men. In women, a total of 286 genome-wide significant SNPs at ten independent loci were discovered. Meta-analysis of sex-stratified GWAS outputs revealed a further 87 independent associated SNPs. Gene-level analyses revealed sex-specific MCP associations, with 31 genes significantly associated in females, 37 genes associated in males, and a single gene, DCC, associated in both sexes. We found evidence for sex-specific pleiotropy and risk for MCP was found to be associated with chronic widespread pain in a sex-differential manner. Male and female MCP were highly genetically correlated, but at an rg of significantly less than 1 (0.92). All 37 male MCP-associated genes and all but one of 31 female MCP-associated genes were found to be expressed in the dorsal root ganglion, and there was a degree of enrichment for expression in sex-specific tissues. Overall, the findings indicate that sex differences in chronic pain exist at the SNP, gene and transcript abundance level, and highlight possible sex-specific pleiotropy for MCP. Results support the proposition of a strong central nervous-system component to chronic pain in both sexes, additionally highlighting a potential role for the DRG and nociception.

Familial and Genetic Influences on the Common Pediatric Primary Pain Disorders: A Twin Family Study

The primary pain disorders of childhood are highly prevalent but have infrequently been studied collectively. Genetic influences have been suggested to be causally implicated. Surveys were sent to 3909 Australian twin families, assessing the lifetime prevalence of growing pains, migraine, headache, recurrent abdominal pain, low back pain, and persistent pain (not otherwise specified) in pediatric twins and their immediate family members. Comparisons between monozygous (MZ) and dizygous (DZ) twin pair correlations, concordances and odds ratios were performed to assess the contribution of additive genetic influences. Random-effects logistic regression modelling was used to evaluate relationships between twin individuals and their co-twins, mothers, fathers and oldest siblings with the subject conditions. Twin analyses of responses from 1016 families revealed significant influence of additive genetic effects on the presence of growing pains, migraine, and recurrent abdominal pain. The analyses for headache, low back pain, and persistent pain overall did not conclusively demonstrate that genetic influences were implicated more than shared environmental factors. Regression analyses demonstrated varying levels of significance in relationships between family members and twin individuals for the tested conditions, with strongest support for genetic influences in growing pains and migraine. These data, together with previously published association analyses, suggest common causal influences including genes.

Genetic and environmental effects on lumbar posture, flexibility and motion control in healthy adults

BACKGROUND

Although alterations in posture, flexibility, and motion control of the lumbar spine are associated with low back pain, the underlying interplay between genetic and environmental influences on these traits remains unclear. The aim of this study is to investigate the extent to which genetics and the environment influence lumbar lordosis, flexibility, and motion control.

DESIGN

The present cross-sectional and observational study employed the classic twin design with structural equation models.

METHODS

An inertial measurement unit with a wireless movement analysis system, the ViMove (DorsaVi, Melbourne, Australia) was used to measure lumbar lordosis, flexibility, and motion control during range of motion and functional tests. Intraclass correlation was used to determine twin resemblance for the traits. Heritability (genetic influence on trait variation) of lumbar lordosis, flexibility and motion control was estimated from 52 healthy twins, 34 monozygotic and 18 dizygotic using age and sex adjusted univariate genetic models.

RESULTS

A strong heritability estimate was found in lumbar lordosis (77%, 95% confidence interval [CI]: 38%-91%) in standing, followed by lumbar flexibility (67%, 95% CI: 32%-85%) in the sagittal plane. No significant intraclass correlations were found in monozygotic twin pairs for lumbar motion control or in dizygotic twin pairs during the hurdle step and in-line lunge test.

CONCLUSION

Genetic factors appear to have a substantial influence on lumbar lordosis and lumbar sagittal flexibility. Lumbar motion control may be more influenced by environmental factors.

Profile and management of patients with low back pain complaints in a Brazilian Emergency Department: a cross-sectional retrospective study

Objective: To describe the demographic profile and the management of patients with low back pain (LBP) complaints presenting to the Emergency Department (ED) of a Brazilian public hospital. Methods: Retrospective, cross-sectional study using a convenience sample of patients with LBP triaged at the studied ED through the Manchester Triage System along a year. Data were extracted from electronic medical records. LBP presentations were classified as non-traumatic, traumatic, and non-spinal related pain according to the signs and symptoms reported. Data included patients’ demographic profile, pain severity and management (e.g., imaging exams, medication prescription and hospitalization). Results: Data from 2016 patients was analyzed. Most were middle-aged adults (mean age = 40.5years, SD 15.7), female (n = 1043, 51.7%) and presented moderate pain intensity (score range 4 to 7 on the Visual Analogue Scale, n=1,471; 74.1%). Non-traumatic pain (n = 1,016; 50.4%) was the main cause of care-seeking. A total of 36.9% (n = 743) underwent imaging exams and 42.2% (n = 850) received medication. Patients with non-spinal related pain were three times more likely to receive opioid medication (OR = 2.96; 95%CI 2.30 to 3.79). Conclusion: Non-traumatic LBP (i.e., no history of trauma or red flags) was the main cause of LBP care-seeking in a Brazilian ED. Most patients were treated conservatively and without hospitalization. Opioids prescription and imaging exams, although performed on a smaller scale, were still used for of the management of this type of LBP.

Cohort profile: the AUstralian Twin BACK pain and physical activity study (AUTBACK study)

PURPOSE

Despite the growing evidence that physical activity and familial factors play a role in low back pain (LBP), there is a lack of robust longitudinal studies that (1) investigate the types and dosages of physical activity that are protective or harmful for LBP, (2) employ objective measures of physical activity and (3) conduct appropriate adjustment for confounders. The AUstralian Twin BACK (AUTBACK) study was established to elucidate the longitudinal LBP-physical activity relationship with the benefits of controlling for familial (both genetic/nongenetic) factors that may influence physical activity engagement and LBP.

PARTICIPANTS

Participants are twins registered at Twins Research Australia (TRA), older than 18 years, with access to internet. We collected data on LBP status (weekly) and physical activity levels (monthly) for 12 months as well as a wide range of health, lifestyle and physical activity (objective, self-reported, including different types and dosages) data.

FINDINGS TO DATE

We included 401 twins, 157 being complete twin pairs (n=314). Lifetime prevalence of LBP was 85%. Participants spent 61% of their week in sedentary time and only 4% in moderate/vigorous intensity physical activity (accelerometer). So far, 168 participants (40% of the sample) have completed the 12-month follow-up. A total of 7150 weekly (LBP status) and 1763 monthly questionnaires (physical activity status) have been answered (92% response rate).

FUTURE PLANS

The 12-month follow-up will be completed by June 2020. This cohort represents a novel and comprehensive resource for researchers in the field, and includes high-quality, and frequent data on LBP and physical activity. It allows the investigation of genetic and shared environmental factors on the LBP-physical activity relationship. The AUTBACK group has planned a number of projects, with the main one being the investigation of the influence of physical activity on recurrence of LBP. Data linkage opportunities are available, including with other studies conducted by TRA.

Insight into the genetic architecture of back pain and its risk factors from a study of 509,000 individuals

Back pain (BP) is a common condition of major social importance and poorly understood pathogenesis. Combining data from the UK Biobank and CHARGE consortium cohorts allowed us to perform a very large genome-wide association study (total N = 509,070) and examine the genetic correlation and pleiotropy between BP and its clinical and psychosocial risk factors. We identified and replicated 3 BP-associated loci, including one novel region implicating SPOCK2/CHST3 genes. We provide evidence for pleiotropic effects of genetic factors underlying BP, height, and intervertebral disk problems. We also identified independent genetic correlations between BP and depression symptoms, neuroticism, sleep disturbance, overweight, and smoking. A significant enrichment for genes involved in the central nervous system and skeletal tissue development was observed. The study of pleiotropy and genetic correlations, supported by the pathway analysis, suggests at least 2 strong molecular axes of BP genesis, one related to structural/anatomical factors such as intervertebral disk problems and anthropometrics, and another related to the psychological component of pain perception and pain processing. These findings corroborate with the current biopsychosocial model as a paradigm for BP. Overall, the results demonstrate BP to have an extremely complex genetic architecture that overlaps with the genetic predisposition to its biopsychosocial risk factors. The work sheds light on pathways of relevance in the prevention and management of low BP.

[Acute back pain: minimizing the risks of therapy as the basis for effective treatment]

Dorsopathies are one of the most common pathologies in the practice of a neurologist and therapist. Lower back pain as a leader in years lived with disability. Clinical differential diagnosis using red flags can significantly reduce the proportion of patients with unreasonable examinations. Stratifying patients for the risk of chronic pain and delayed recovery also reduces the risks of prolonged NSAID therapy. Identification of risk groups for cardiovascular and gastrointestinal complications and differentiated prescription of drugs helps to reduce the risks of therapy.

The association between physical activity and low back pain: a systematic review and meta-analysis of observational studies

The aim of this review was to investigate the association between total and domain-specific physical activity (PA) and non-specific low back pain (LBP) in adults. Seven databases were searched for cohort and cross-sectional studies. Pooled estimates of the association of medium and high levels PA and LBP, using the generic inverse-variance method with fixed- and random-effects models were calculated. Twenty-four studies (15 cohort and nine cross-sectional; 95,796 participants) were included. The pooled fully adjusted risk ratios (RR) from cohort studies comparing medium with lowest activity levels were 0.90 (95%CI 0.85 to 0.96) for total PA, and 0.90 (95%CI 0.85 to 0.96) for leisure-time PA (LTPA). The pooled RR comparing highest with lowest activity levels were 1.00 (95%CI 0.92 to 1.08) for total PA, and 1.01 (95%CI 0.93 to 1.10) for LTPA. The pooled fully adjusted odds ratios (OR) from cross-sectional studies comparing medium with lowest activity levels were 0.93 (95%CI 0.65 to 1.32) for total PA, and 0.77 (95%CI 0.62 to 0.96) for LTPA. The pooled OR comparing highest with lowest activity levels were 1.05 (95%CI 0.89 to 1.23) for total PA, and 0.85 (95%CI 0.79 to 0.93) for LTPA. PA seems to be associated with lower prevalence of LBP.

The Risk Factors of Low Back Pain in Female High School Students

STUDY DESIGN

A prospective cross-sectional study.

OBJECTIVE

The aim of this study was to evaluate the prevalence and associated factors with low back pain (LBP) in female adolescents of high school age.

SUMMARY OF BACKGROUND DATA

The prevalence of LBP in Tehran is high, and the majority of previous studies on LBP in adolescent and its risk factors have been performed in the developed countries. Therefore, identification of risk factors and planning appropriate protocols for prevention of LBP in adolescents may substantially decrease the prevalence of LBP and its burden in developing countries in future.

METHODS

In a prospective cross-sectional study, demographic characteristics, including age, body mass index (BMI), weight and mode of using backpack, family history of LBP in first degree relatives, and passive smoking status of the participants along with a history of LBP were recorded. Joint hypermobility was assessed using Beighton scale. Also, anthropometric measurements, spinal flexion, and hip joint range of motion were measured for each participant.

RESULTS

In total, 372 students participated in the study. The mean (SD) age of the participants was 15.8 (0.9) years. The lifetime, more than 3 months, and last month history of LBP was 46.2%, 11.6%, and 31.2%, respectively. Positive history of LBP in the first-degree relatives was significantly associated with LBP in the participants (P < 0.01). The prevalence of passive smoking was significantly higher in the participants with last month history of LBP (P = 0.03). The prevalence of joint hypermobility was 15.9% and was significantly higher in those with the lifetime and last month history of LBP (P < 0.01).

CONCLUSION

LBP is a common complaint among adolescent and high school girl students. The results of this study identified the prevalence and associated factors with LBP in high school students and will help develop strategies for prevention and treatment of LBP in the adolescent population.

LEVEL OF EVIDENCE

3.

Low back pain

Low back pain affects individuals of all ages and is a leading contributor to disease burden worldwide. Despite advancements in assessment and treatment methods, the management of low back pain remains a challenge for researchers and clinicians alike. One reason for the limited success in identifying effective treatments is the large variation in the manifestations, possible causes, precipitating and maintaining factors, course, prognosis and consequences in terms of activity interference and quality of life. However, despite these challenges, steady progress has been achieved in the understanding of back pain, and important steps in the understanding of the psychological and social risk factors, genetics and brain mechanisms of low back pain have been made. These new findings have given impetus to the development of new diagnostic procedures, evidence-based screening methods and more targeted interventions, which underscore the need for a multidisciplinary approach to the management of low back pain that integrates biological, psychological and social aspects.

Lifetime cigarette smoking and chronic widespread and regional pain in later adulthood: evidence from the 1946 British birth cohort study

OBJECTIVE

To examine whether different lifetime patterns of cigarette smoking are associated with chronic widespread pain (CWP) and chronic regional pain (CRP) at age 68.

DESIGN

Prospective cohort study.

SETTING

England, Scotland and Wales.

PARTICIPANTS

Up to 2347 men and women from the Medical Research Council National Survey of Health and Development, who have been followed up since birth in 1946 and provided sufficient information on cigarette smoking across adulthood to be classified as never smoker, predominantly non-smoker, predominantly smoker or lifelong smoker and pain assessment at age 68.

PRIMARY OUTCOME MEASURES

Pain was self-reported at age 68, and CWP was defined according to American College of Rheumatology criteria. Participants who reported having pain for ≥3 months but who did not meet the CWP definition were classified as having CRP; those who reported pain which had lasted for <3 months were classified as 'other' pain. No pain was the reference group.

RESULTS

Findings from multinomial logistic regression models indicated that compared with never smokers, predominantly non-smokers, predominantly smokers and lifelong smokers all had an increased risk of CWP; relative risk ratios=1.70(95% CI 1.16 to 2.49); 2.10(95% CI 1.34 to 3.28) and 1.88(95% CI 0.99 to 3.57), respectively, after adjusting for sex, own occupational class, educational level, body mass index, leisure time physical activity, alcohol intake, long-standing illness and symptoms of anxiety and depression. No association was observed between smoking history and CRP or other pain.

CONCLUSIONS

These results suggest that exposure to cigarette smoking at any stage in adulthood was associated with higher risk of CWP in later adulthood; highlighting the ongoing importance of smoking prevention programmes. It also suggests that assessment of lifetime smoking behaviour may be more useful in identifying those at greater risk of CWP in later life than assessment of current smoking status.

Low back pain, obesity, and inflammatory markers: exercise as potential treatment

Low back pain is a health issue with significant impact to patients and society. This narrative review aims to synthesize the relationship between obesity, low-grade inflammation and low back pain. It is known that a sedentary lifestyle is a risk factor for obesity and related disorders. The adipose tissue of obese people secretes a range of cytokines of character pro- and anti-inflammatory, with many molecular effects. In addition, pro-inflammatory cytokines are sensitizers of C-reactive protein (CRP), a marker of acute inflammation that can be linked to the musculoskeletal pain sensation individuals with back pain. Another inflammatory marker deserves mention, prostaglandin E2. Prostaglandin E2 is important in the process of triggering actions such as pyrexia, sensation of pain and inflammation, which are exhibited in low back pain condition. The potential for exercises and physical activity to control these mediators and act as a preventative measure for back pain are important because they work as a nonpharmacological strategy to this target audience. There are two types of exercise discussed in this review, the moderate-intensity continuous training and high-intensity interval training.

Behavior-Related Factors Associated With Low Back Pain in the US Adult Population

STUDY DESIGN

This study is based on data from the 2009-2012 National Health Interview Survey (NHIS) of the civilian population of the United States. The NHIS focuses on a number of health conditions, including low back pain.

OBJECTIVE

The objective of this study is to explore behavior-related factors associated with low back pain in the US adult population, including leisure-time physical activity, alcohol use, tobacco use, sleep duration, and obesity.

SUMMARY OF BACKGROUND DATA

Low back pain is a prevalent musculoskeletal health disorder with profound impact on individuals, business, and society. Addressing behavior-related factors holds the potential to reduce the burden of low back pain on a societal basis.

METHODS

To account for the complex sampling design of the NHIS, the Taylor linearized variance estimation methods were used to conduct weighted descriptive statistics and multivariate logistic regression analyses in exploring the relationships between low back pain and a set of behavior-related risk factors.

RESULTS

This study shows associations between self-reported lower back pain and reported leisure-time physical inactivity, current or former smoking, current or former alcohol drinking, short sleep duration, and obesity.

CONCLUSION

This study identified a number of behavior-related factors that appear to have a significant relationship with low back pain. Public health policy makers and clinicians should consider these factors to reduce the burden of low back pain. This study supports the need for longitudinal study design in future research.

LEVEL OF EVIDENCE

2.

Changes of lumbar posture and tissue loading during static trunk bending

Static trunk bending is an occupational risk factor for lower back pain (LBP). When assessing relative short duration trunk bending tasks, existing studies mostly assumed unchanged spine biomechanical responses during task performance. The purpose of the current study was to assess the biomechanical changes of lumbar spine during the performance of relatively short duration, sustained trunk bending tasks. Fifteen participants performed 40-s static trunk bending tasks in two different trunk angles (30° or 60°) with two different hand load levels (0 or 6.8 kg). Results of the current study revealed significantly increased lumbar flexion and lumbar passive moment during the 40 s of trunk bending. Significantly reduced lumbar and abdominal muscle activities were also observed in most conditions. These findings suggest that, during the performance of short duration, static trunk bending tasks, a shift of loading from lumbar active tissues to passive tissues occurs naturally. This mechanism is beneficial in reducing the accumulation of lumbar muscle fatigue; however, lumbar passive tissue creep could be introduced due to prolonged or repetitive exposure.

Barriers to Physical Activity in Low Back Pain Patients following Rehabilitation: A Secondary Analysis of a Randomized Controlled Trial

Background

Promoting health-enhancing physical activity following rehabilitation is a well-known challenge. This study analysed the barriers to leisure time activity among low back pain patients.

Methods

A subset of 192 low back pain patients who participated in a randomized controlled trial promoting physical activity was analysed. Physical activity, barriers, and sociodemographic and indication-related variables were assessed by a questionnaire. Differences in barriers between active and inactive participants were tested by Pearson's chi squared test. A logistic regression model was fitted to identify influencing factors on physical activity at six months following rehabilitation.

Results

Inactive and active participants differed significantly in nine of the 19 barriers assessed. The adjusted regression model showed associations of level of education (OR = 5.366 [1.563; 18.425]; p value = 0.008) and fear of pain (OR = 0.612 [0.421; 0.889]; p value = 0.010) with physical activity. The barriers included in the model failed to show any statistically significant association after adjustment for sociodemographic factors.

Conclusions

Low back pain patients especially with a low level of education and fear of pain seem to need tailored support in overcoming barriers to physical activity. This study is registered at German Clinical Trials Register (DRKS00004878).

Are people with chronic low back pain meeting the physical activity guidelines? A co-twin control study

BACKGROUND

Despite a large amount of research investigating physical activity (PA) levels in people with chronic low back pain (LBP), no study has investigated whether people with chronic LBP are meeting the World Health Organization (WHO) PA guidelines. Furthermore, with genetics and the early shared environment substantially influencing the presence of LBP and PA engagement, these factors could confound the association between LBP and PA and need to be controlled for.

PURPOSE

This study aimed to investigate the association between chronic LBP and meeting the PA guidelines, while controlling for the effects of genetics and early shared environment.

DESIGN

This is a cross-sectional co-twin control study.

PATIENT SAMPLE

A cross-sectional analysis was performed on 1,588 twins from the Murcia Twin Registry in Spain with available data on LBP and PA from the 2013 data collection wave.

OUTCOME MEASURES

The exposure and outcome variables in our study were self-reported. Twins reporting a history of chronic LBP were asked follow-up questions to inform on the presence of recent LBP (within the past 4 weeks), previous LBP (no pain within the past 4 weeks), and persistent LBP (no pain-free month in the last 6 months). These were our exposure variables. Our outcome variable was meeting the WHO PA guidelines, which involved at least 75 minutes of vigorous-intensity PA, or at least 150 minutes of moderate-intensity PA per week.

METHODS

To investigate the association between chronic LBP and meeting the PA guidelines, we first performed a multivariate logistic regression on the total sample of twins. Co-variables entered the model if the univariate association between the co-variable, and both the exposure and the outcome reached a significance of p<.2. Second, to adjust for the influence of genetics and early shared environment, we performed a conditional multivariate logistic regression on complete twin pairs discordant for LBP. The Murcia Twin Registry is supported by Fundación Séneca, Regional Agency for Science and Technology, Murcia, Spain (08633/PHCS/08 and 15302/PHCS/10) and the Ministry of Science and Innovation, Spain (PSI11560-2009). Funding for this project has also been received from Fundación MAPFRE (2012). The authors declare that there are no conflicts of interest.

RESULTS

There was a significant inverse association between recent LBP and meeting the PA guidelines (odds ratio [OR]=0.71, p=.034). When controlling for genetics and early shared environment, this association disappeared. There was no association between previous (OR=0.95, p=.779) or persistent LBP (OR=0.78, p=.192) and meeting the PA guidelines.

CONCLUSION

Twins with recent LBP are less likely to meet the PA guidelines than those with no history of chronic LBP, highlighting the importance of incorporating PA promotion in the treatment of these individuals. Genetics and early shared environment appear to be confounding the association between LBP and PA, although this needs to be further tested in larger twin samples.

Correlation of Body Composition and Low Back Pain Severity in a Cross-Section of US Veterans

OBJECTIVE

Back pain is more prevalent in the obese, but whether back pain severity is directly correlated to obesity in veterans is unknown. We sought to determine if there was a correlation between body composition and low back pain severity in a sample of veterans. The hypothesis was that veterans with higher body mass index values would report higher low back pain severity scores.

METHODS

This study was a retrospective chart review of 1768 veterans presenting to a Veterans Affairs chiropractic clinic with a chief complaint of low back pain between January 1, 2009 and December 31, 2014. Spearman's rho was used to test for correlation between body composition as measured by body mass index and low back pain severity as measured by the Back Bournemouth Questionnaire.

RESULTS

On average, the sample was predominantly male (91%), older than 50, and overweight (36.5%) or obese (48.9%). There was no correlation between body mass index and Back Bournemouth Questionnaire scores, r = .088, p < .001.

CONCLUSIONS

The majority of veterans with low back pain in this sample were either overweight or obese. There was no correlation between body composition and low back pain severity in this sample of veterans.

Mapping the association between back pain and type 2 diabetes: A cross-sectional and longitudinal study of adult Spanish twins

BACKGROUND

Back pain and type 2 diabetes often co-occur, resulting in greater impact on people's health and complexity in their care. Plausible causal mechanisms for this association have been proposed, yet the nature of the link remains unclear. We therefore explored the direction of the association between type 2 diabetes and chronic back pain in twins, controlling for genetics and early environmental confounding.

METHODS

2,096 and 1,098 twins were included in the cross-sectional and longitudinal analyses, respectively. Any or severe (≥ 9) low back pain (LBP), neck pain (NP), and spinal pain (concurrent LBP and NP) and type 2 diabetes were investigated. Sequential analyses were performed using logistic regression. Firstly, twins were analysed unpaired (adjusted age and gender): total sample analyses. Then, to control for genetic and shared environmental factors, a co-twin case-control analysis was performed including monozygotic and dizygotic twin pairs discordant for back pain (cross-sectional only).

RESULTS

In the cross-sectional total sample analyses, type 2 diabetes was associated with chronic spinal pain (OR 1.61; 95%CI 1.12 to 2.31), severe chronic spinal pain (OR 3.33; 95%CI 1.47 to 7.53), chronic NP (OR 1.37; 95%CI 1.01 to 1.85), severe chronic NP (OR 2.28; 95%CI 1.24 to 4.21), and severe chronic LBP (OR 1.63; 95%CI 1.00 to 2.64). After further adjustment for genetic and shared environmental factors, none of the associations remained significant. The longitudinal analyses indicated that the presence of type 2 diabetes did not increase the risk of future back pain, or vice-versa, after two to four years.

CONCLUSIONS

Chronic back pain (spinal pain, NP, or LBP) was associated with the prevalence of type 2 diabetes. Associations are stronger for severe cases of pain. Future research should investigate the temporal relationships between these conditions with longer follow up in twins.

Modifiable risk factors for chronic back pain: insights using the co-twin control design

BACKGROUND

Inconsistent associations between modifiable risk factors and chronic back pain (CBP) may be due to the inability of traditional epidemiologic study designs to properly account for an array of potential genetic and environmental confounding factors. The co-twin control research design, comparing modifiable risk factors in twins discordant for CBP, offers a unique way to remove numerous confounding factors.

PURPOSE

The study aimed to examine the association of modifiable lifestyle and psychological factors with lifetime CBP.

STUDY DESIGN/SETTING

This is a cross-sectional co-twin control study in a nationwide sample of male twin members of the Vietnam Era Twin Registry.

PATIENT SAMPLE

The sample is composed of 7,108 participants, including 1,308 monozygotic (MZ) pairs and 793 dizygotic pairs.

OUTCOME MEASURE

The outcome measure is the self-reported lifetime history of CBP.

METHODS

Lifestyle factors included body mass index (BMI), smoking history, alcohol consumption, habitual physical activity, and typical sleep duration. Psychological factors included depression (Patient Health Questionnaire-9) and posttraumatic stress disorder (PTSD) symptoms (PTSD Checklist). Covariates included age, race, education, and income. Odds ratios (ORs) and 95% confidence intervals (CI) were estimated for the association of risk factors with lifetime CBP when considering twins as individuals, and a within-pair co-twin control analysis that accounted for familial and genetic factors. Funding was through VA Grant 5IK2RX001515; there were no study-specific conflicts of interest.

RESULTS

The mean age of respondents was 62 years and the prevalence of lifetime CBP was 28%. All lifestyle factors were associated with CBP in the individual level analysis. However, none of these persisted in the within-pair analyses, except for severe obesity (BMI ≥35.0), which was associated with lifetime CBP in both individual-level (OR=1.6, 95% CI: 1.3-1.9) and within-pair analyses (MZ analysis: OR=3.7, 95% CI: 1.2-11.4). Symptoms of PTSD and depression were strongly associated with lifetime CBP in both the individual-level (moderate or severe depression: OR=4.2, 95% CI: 3.6-4.9, and severe PTSD: OR=4.8, 95% CI: 4.0-5.7) and within-pair (MZ) analyses (moderate or severe depression: OR=4.6, 95% CI: 2.4-8.7, and severe PTSD: OR=3.2, 95% CI: 1.6-6.5).

CONCLUSIONS

Many associations between modifiable lifestyle risk factors and CBP are due to confounding by familial and genetic factors. Severe obesity, depression, and PTSD should be considered in the development of intervention strategies to reduce the prevalence of CBP.

The Brazilian Twin Registry

The Brazilian Twin Registry (BTR) was established in 2013 and has impelled twin research in South America. The main aim of the initiative was to create a resource that would be accessible to the Brazilian scientific community as well as international researchers interested in the investigation of the contribution of genetic and environmental factors in the development of common diseases, phenotypes, and human behavior traits. The BTR is a joint effort between academic and governmental institutions from Brazil and Australia. The collaboration includes the Federal University of Minas Gerais (UFMG) in Brazil, the University of Sydney and University of Melbourne in Australia, the Australian Twin Registry, as well as the research foundations CNPq and CAPES in Brazil. The BTR is a member of the International Network of Twin Registries. Recruitment strategies used to register twins have been through participation in a longitudinal study investigating genetic and environmental factors for low back pain occurrence, and from a variety of sources including media campaigns and social networking. Currently, 291 twins are registered in the BTR, with data on demographics, zygosity, anthropometrics, and health history having been collected from 151 twins using a standardized self-reported questionnaire. Future BTR plans include the registration of thousands of Brazilian twins identified from different sources and collaborate nationally and internationally with other research groups interested on twin studies.

Genetic and Environmental Risk for Chronic Pain and the Contribution of Risk Variants for Major Depressive Disorder: A Family-Based Mixed-Model Analysis

BACKGROUND

Chronic pain is highly prevalent and a significant source of disability, yet its genetic and environmental risk factors are poorly understood. Its relationship with major depressive disorder (MDD) is of particular importance. We sought to test the contribution of genetic factors and shared and unique environment to risk of chronic pain and its correlation with MDD in Generation Scotland: Scottish Family Health Study (GS:SFHS). We then sought to replicate any significant findings in the United Kingdom Biobank study.

METHODS AND FINDINGS

Using family-based mixed-model analyses, we examined the contribution of genetics and shared family environment to chronic pain by spouse, sibling, and household relationships. These analyses were conducted in GS:SFHS (n = 23,960), a family- and population-based study of individuals recruited from the Scottish population through their general practitioners. We then examined and partitioned the correlation between chronic pain and MDD and estimated the contribution of genetic factors and shared environment in GS:SFHS. Finally, we used data from two independent genome-wide association studies to test whether chronic pain has a polygenic architecture and examine whether genomic risk of psychiatric disorder predicted chronic pain and whether genomic risk of chronic pain predicted MDD. These analyses were conducted in GS:SFHS and repeated in UK Biobank, a study of 500,000 from the UK population, of whom 112,151 had genotyping and phenotypic data. Chronic pain is a moderately heritable trait (heritability = 38.4%, 95% CI 33.6% to 43.9%) that is significantly concordant in spouses (variance explained 18.7%, 95% CI 9.5% to 25.1%). Chronic pain is positively correlated with depression (ρ = 0.13, 95% CI 0.11 to 0.15, p = 2.72x10-68) and shows a tendency to cluster within families for genetic reasons (genetic correlation = 0.51, 95%CI 0.40 to 0.62, p = 8.24x10-19). Polygenic risk profiles for pain, generated using independent GWAS data, were associated with chronic pain in both GS:SFHS (maximum β = 6.18x10-2, 95% CI 2.84 x10-2 to 9.35 x10-2, p = 4.3x10-4) and UK Biobank (maximum β = 5.68 x 10-2, 95% CI 4.70x10-2 to 6.65x10-2, p < 3x10-4). Genomic risk of MDD is also significantly associated with chronic pain in both GS:SFHS (maximum β = 6.62x10-2, 95% CI 2.82 x10-2 to 9.76 x10-2, p = 4.3x10-4) and UK Biobank (maximum β = 2.56x10-2, 95% CI 1.62x10-2 to 3.63x10-2, p < 3x10-4). Limitations of the current study include the possibility that spouse effects may be due to assortative mating and the relatively small polygenic risk score effect sizes.

CONCLUSIONS

Genetic factors, as well as chronic pain in a partner or spouse, contribute substantially to the risk of chronic pain for an individual. Chronic pain is genetically correlated with MDD, has a polygenic architecture, and is associated with polygenic risk of MDD.

Neurobiological Phenotypes of Familial Chronic Pain in Adolescence: A Pilot fMRI Study

Parental history of chronic pain has been associated with self-reported pain in adolescent offspring. This suggests that there may be neurobiological mechanisms associated with pain heritability. Because emotional circuitry is an important component of pain processing and may also influence cognition, we used functional magnetic resonance imaging to examine affective processing and cognitive control using an Emotional Go/NoGo task in youth with (FH + Pain, n = 8) and without (FH - Pain, n = 8) a parental history of chronic pain (mean age = 14.17 ± .34 years). FH + Pain youth had widespread reductions in brain activity within limbic and visual processing regions during processing of positively valenced emotional stimuli, as well as reduced frontoparietal response while processing negatively valenced emotional stimuli compared with their peers. In addition, during inhibition within a positive emotional context, FH + Pain youth had reduced cognitive control and salience-related brain activity. On the other hand, default mode-related brain response was increased during inhibitory control within a negative emotional context in these adolescents compared with their peers (P/α < .05). The current findings indicate differences in both emotional processing and cognitive control brain response in FH + Pain compared with FH - Pain youth, suggesting that both affective and executive functioning pathways may be important markers related to the intergenerational transmission of pain. Perspective: This is the first study to examine neurobiological markers of pain risk in adolescents with a family history of chronic pain. These findings may aid in the identification of neural phenotypes related to vulnerability for the onset of pain in at-risk youth.

Are obesity and body fat distribution associated with low back pain in women? A population-based study of 1128 Spanish twins

PURPOSE

To investigate the relationship between different measures of obesity and chronic low back pain (LBP) using a within-pair twin case-control design that adjusts for genetics and early shared environment.

METHODS

A cross-sectional association between lifetime prevalence of chronic LBP and different measures of obesity (body mass index-BMI; percent body fat; waist circumference; waist-hip ratio) was investigated in 1128 female twins in three stages: (i) total sample analysis; (ii) within-pair case-control analysis for monozygotic (MZ) and dizygotic (DZ) twins together; (iii) within-pair case-control analysis separated by DZ and MZ. Odds ratios (OR) and 95% confidence intervals (CI) were calculated.

RESULTS

BMI (OR 1.12; 95% CI 1.02-1.26) and percent body fat (OR 1.15; 95% CI 1.01-1.32) were weakly associated with lifetime prevalence of chronic LBP in the total sample analysis but were absent when shared environment and genetic factors were adjusted for using the within-pair case-control analysis. Greater waist-hip ratios were associated with smaller prevalence estimates of chronic LBP in the within-pair case-control analysis with both MZ and DZ twins (OR 0.67; 95% CI 0.47-0.94). However, this association did not remain after the full adjustment for genetic factors in the MZ within-pair case-control analysis.

CONCLUSIONS

BMI, percent of fat mass and greater depositions of fat and mass around the hips are associated with increases in chronic LBP prevalence in women but these associations are small and appear to be confounded by the effects of genetics and early shared environment. Therefore, our results do not support a causal direct relationship between obesity and chronic LBP.

Physical activity and health-related quality of life in chronic low back pain patients: a cross-sectional study

Background

The aim of the present study was to identify the relationship of physical activity (PA) and Health-Related Quality of Life (HRQoL) in patients suffering from low back pain (LBP).

Methods

The present evaluation was conducted as a cross-sectional study based on baseline data of an randomized controlled trial on the effectiveness of an intervention promoting PA. Patients answered a questionnaire on domain specific PA (GPAQ) and HRQoL (EQ-5D-5 L). Furthermore, sociodemographic and indication-specific variables as well as work-related aspects were assessed. Associations of PA and HRQoL were estimated by means of regression analysis: one regression model only included domain specific PA (model 1) and a second regression model additionally included further variables (model 2).

Results

412 patients completed the questionnaire. Model 1 showed opposed effects of workplace and leisure time PA: while workplace PA showed a negative association (β = −0.064; p = 0.04), a positive association of leisure time PA could be proved (β = 0.068; p = 0.01). Model 2 showed that only the variables “current work ability” (β = −0.030; p < 0.01) and “intensity of pain” (β = 0.104; p < 0.01) significantly contributed to explain the variance in HRQoL (model 2).

Conclusions

The present results indicate the necessity of a differentiation of workplace and leisure time PA in the context of assessing health-enhancing effects of PA in LBP patients. In the context of HRQoL it must be assumed that the relevance of PA might be overestimated. Further research should be performed on predictors of HRQoL and thereby particular attention should be paid on the patients’ work-related and indication-specific aspects.

Movement coaching: study protocol of a randomized controlled trial evaluating effects on physical activity and participation in low back pain patients

BACKGROUND

Chronic Low Back Pain is a complex syndrome with multifactorial bio-psycho-social etiology and interdependences. Thereby, physical activity seems to play an essential role regarding the prevention and rehabilitation of LBP. In consequence, physical activity and exercise therapy is an integral part of musculoskeletal rehabilitation in LBP. However, adherence to self-directed exercise and implementing a health-enhancing physical activity in daily routine after rehabilitation is a common problem for patients and only a few patients integrate health-enhancing physical activity and/or sport activities in their lifestyle. The present paper describes a comprehensive multilevel approach combining face-to-face intervention, telephone and internet aftercare (Movement Coaching). Aim of the trial presented in this study protocol is to evaluate effectiveness of Movement Coaching compared to a control intervention.

METHODS/DESIGN

The study is a prospective, single-blinded, monocenter randomized controlled trial (RCT) with three measuring points: T1=start of inpatient rehabilitation; T2=six months follow-up; T3=twelve months follow-up. In total, 412 patients were recruited. The intervention involves small-group face-to-face contact during inpatient rehabilitation (two times, week 2 & 3) and telephone aftercare (week 8 & week 12 after rehabilitation) as well as internet-based aftercare (web 2.0 platform; available until six months after rehabilitation). Primary outcome is physical activity, assessed by GPAQ questionnaire. The final data collection is expected by April 2015.

DISCUSSION

Due to the burden of physical inactivity, there is a need to develop, evaluate and disseminate approaches that are effective in promoting physical activity and especially promoting the maintenance of physical activity in relevant target groups. Considering the high prevalence and socioeconomic impact of low back pain and its multifactorial etiology, low back pain patients seem to be a relevant target group for physical activity promotion. A multilevel approach to bridge the interface of (inpatient) rehabilitation and self-directed physical activity will help to target group-specific PA promotion.

TRIAL REGISTRATION

German Clinical Trials Register (DRKS)-ID: DRKS00004878.