Heritability of spinal pain and consequences of spinal pain: A comprehensive genetic epidemiologic analysis using a population-based sample of 15,328 twins ages 20-71 years

Global burden of neck pain and its gender and regional inequalities from 1990 - 2021: a comprehensive analysis from the Global Burden of Disease Study 2021

BACKGROUND

Neck pain is a growing public health concern, no recent research has comprehensively examined its incidence and years lived with disability (YLDs) across different regions and genders. For the first time, this study aims to provide the most recent estimates on the global burden of neck pain between 1990 and 2021 obtained from the 2021 global burden of disease (GBD) database, focusing on regional and gender inequalities. We also predict future trends, highlighting its increasing impact on public health.

MATERIALS AND METHODS

The study was conducted retrospectively using publicly available data from the GBD 2021 database, acquired on August 20, 2024. The incidence and burden of neck pain were assessed using DisMod-MR 2.1. Data on incidence and years lived with disability (YLDs) rates per 100,000 people were obtained for countries, regions, ages, and sexes globally.

RESULTS

In 2021, the global age-standardized rates for incidence, and YLDs of neck pain per 100,000 population was 519 (95% uncertainty interval, 408-633), and 242 (163-343) per 100,000 population, respectively. Joinpoint regression showed both rates demonstrated an overall increasing trend from 1990 to 2021 worldwide. Projections suggest a slight decline in these rates for the coming years. Women consistently showed a higher burden than men across all age groups. Regional analyses indicated that the Islamic Republic of Iran had the highest rates, whereas New Zealand had the lowest. Negative correlations were observed between the Estimated Annual Percentage Change (EAPC) and both the age-standardized rates and the Sociodemographic Index (SDI). Low-SDI countries generally exhibited higher incidence and YLDs rates, whereas high-SDI countries maintained higher YLDs rates despite relatively lower incidence rates.

CONCLUSION

The global burden of neck pain increased between 1990 and 2021, but future projections indicate a potential mild decrease. Gender and regional inequalities persist, underscoring the need for targeted policy interventions focusing on women and low-SDI regions to alleviate the burden of neck pain.

Common Genetic Factors May Play a Role in the Relationships Between Body Composition, Adipokines, and Low-Back-Pain-Related Disability

In this study, we evaluated the contribution of the putative genetic factors into the established associations between selected circulating adipokine levels, body composition measurements, and low-back-pain-related disability scores (LBP_DS). A total of 1078 individuals from 98 nuclear families (with 1 to 11 siblings per family) were examined. A detailed self-report questionnaire was used to collect LBP disability data; body composition (fat, skeletal muscle mass, and extracellular water (ECW)) was assessed using the bioimpedance method; plasma levels of adipokines were measured by ELISA. Pedigree-based statistical analysis methods were used, including family-based variance component analysis (VCA) and principal phenotype analysis (PPA), to estimate the contribution of potential genetic and environmental factors. The VCA revealed a significant additive genetic component in LBP_DS and for the selected body composition phenotypes and adipokines. The study also revealed that both adipokines (GDF-15, chemerin, and follistatin) and body composition variables (BMI, fat mass/weight, waist circumference, and ECW) were genetically correlated with LBP_DS. Next, PPA generated two synthetic phenotypes: PPCT (combining cytokines) and PPBC (combining body composition variables). There was no significant correlation between the putative genetic factors underlying the created PPs. However, each of them displayed a significant genetic correlation with LBP_DS. These findings indicate that genetic factors that are assumingly common for several adipokine variations and several body composition measurements, respectively, presumably have a pleotropic genetic influence on the LBP_DS variation, independently from one another. This, in turn, suggests that the alleged genetic factors employing pleiotropic effects on LBP_DS have a complex and probably non-overlapping composition.

The effect of parental pain, disability benefits and education on risk of long-term sick leave due to musculoskeletal disorders and the modifying effect of sleep and physical activity: the HUNT study

BACKGROUND

Family factors, sleep, and physical activity have previously been associated with risk of sick leave and disability benefits due to musculoskeletal disorders. However, how these factors act during adolescence and young adulthood is unclear. The aim of this study was to (i) examine if chronic pain, disability benefits and education in parents influence the risk of long-term sick leave due to musculoskeletal disorders in young adulthood, and (ii) to explore if offspring sleep problems and physical activity modify these effects.

METHODS

A population-based prospective study of 18,552 adolescents and young adults (≤ 30 years) in the Norwegian HUNT Study. Survey data was linked to national registry data on sick leave, disability benefits, family relations and educational attainment. We used Cox regression to estimate hazard ratio (HR) with 95% confidence interval (CI) for long-term (≥ 31 days) sick leave due to a musculoskeletal disorder in offspring associated with parental factors and the joint effect of parental factors and offspring lifestyle factors.

RESULTS

Parental chronic pain (HR 1.36, 95% CI 1.27-1.45), disability benefits (HR 1.41, 95% CI 1.33-1.48) and low educational attainment (HR 1.78, 95% CI 1.67-1.90) increased the risk of long-term sick leave due to musculoskeletal disorders among offspring. There was no strong evidence that sleep and physical activity modified these effects.

CONCLUSION

Chronic pain, disability benefit and low education in parents increased the risk of long-term sick leave due to musculoskeletal disorders among offspring, but these effects were not modified by offspring sleep problems or physical activity level. The findings suggest that efforts beyond individual lifestyle factors might be important as preventive measures.

Global, regional, and national burden of neck pain, 1990-2020, and projections to 2050: a systematic analysis of the Global Burden of Disease Study 2021

BACKGROUND

Neck pain is a highly prevalent condition that leads to considerable pain, disability, and economic cost. We present the most current estimates of neck pain prevalence and years lived with disability (YLDs) from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) by age, sex, and location, with forecasted prevalence to 2050.

METHODS

Systematic reviews identified population-representative surveys used to estimate the prevalence of and YLDs from neck pain in 204 countries and territories, spanning from 1990 to 2020, with additional data from opportunistic review. Medical claims data from Taiwan (province of China) were also included. Input data were pooled using DisMod-MR 2.1, a Bayesian meta-regression tool. Prevalence was forecast to 2050 using a mixed-effects model using Socio-demographic Index as a predictor and multiplying by projected population estimates. We present 95% UIs for every metric based on the 2·5th and 97·5th percentiles of 100 draws of the posterior distribution.

FINDINGS

Globally, in 2020, neck pain affected 203 million (95% uncertainty interval [UI] 163-253) people. The global age-standardised prevalence rate of neck pain was estimated to be 2450 (1960-3040) per 100 000 population and global age-standardised YLD rate was estimated to be 244 (165-346) per 100 000. The age-standardised prevalence rate remained stable between 1990 and 2020 (percentage change 0·2% [-1·3 to 1·7]). Globally, females had a higher age-standardised prevalence rate (2890 [2330-3620] per 100 000) than males (2000 [1600-2480] per 100 000), with the prevalence peaking between 45 years and 74 years in male and female sexes. By 2050, the estimated global number of neck pain cases is projected to be 269 million (219-322), with an increase of 32·5% (23·9-42·3) from 2020 to 2050. Decomposition analysis of the projections showed population growth was the primary contributing factor, followed by population ageing.

INTERPRETATION

Although age-standardised rates of neck pain have remained stable over the past three decades, by 2050 the projected case numbers are expected to rise. With the highest prevalence in older adults (higher in females than males), a larger effect expected in low-income and middle-income countries, and a rapidly ageing global population, neck pain continues to pose a challenge in terms of disability burden worldwide. For future planning, it is essential we improve our mechanistic understanding of the different causes and risk factors for neck pain and prioritise the consistent collection of global neck pain data and increase the number of countries with data on neck pain.

FUNDING

Bill & Melinda Gates Foundation and Global Alliance for Musculoskeletal Health.

Strong Association of Depression and Anxiety With the Presence of Back Pain While Impact of Spinal Imaging Findings is Limited: Analysis of an MRI Cohort Study

Development of back pain is multifactorial, and it is not well understood which factors are the main drivers of the disease. We therefore applied a machine-learning approach to an existing large cohort study data set and sought to identify and rank the most important contributors to the presence of back pain amongst the documented parameters of the cohort. Data from 399 participants in the KORA-MRI (Cooperative health research in the region Augsburg-magnetic resonance imaging) (Cooperative Health Research in the Region Augsburg) study was analyzed. The data set included MRI images of the whole body, including the spine, metabolic, sociodemographic, anthropometric, and cardiovascular data. The presence of back pain was one of the documented items in this data set. Applying a machine-learning approach to this preexisting data set, we sought to identify the variables that were most strongly associated with back pain. Mediation analysis was performed to evaluate the underlying mechanisms of the identified associations. We found that depression and anxiety were the 2 most selected predictors for back pain in our model. Additionally, body mass index, spinal canal width and disc generation, medium and heavy physical work as well as cardiovascular factors were among the top 10 most selected predictors. Using mediation analysis, we found that the effects of anxiety and depression on the presence of back pain were mainly direct effects that were not mediated by spinal imaging. In summary, we found that psychological factors were the most important predictors of back pain in our cohort. This supports the notion that back pain should be treated in a personalized multidimensional framework. PERSPECTIVE: This article presents a wholistic approach to the problem of back pain. We found that depression and anxiety were the top predictors of back pain in our cohort. This strengthens the case for a multidimensional treatment approach to back pain, possibly with a special emphasis on psychological factors.

Sex differences in lifetime prevalence of low back pain: A multinational study of opposite-sex twin pairs

BACKGROUND

Low back pain (LBP) is more likely to occur in people with a family history of this condition, highlighting the importance of accounting for familial factors when studying the individual risk of LBP. We conducted a study of opposite-sex twin pairs investigating sex differences in LBP while accounting for (genetic and shared environmental) familial factors.

METHODS

We applied a matched co-twin control design to study 795 adult opposite-sex pairs from Australia, Spain, and the United States (US). We used mixed-effects logistic regression to assess the within-pair association between female sex and lifetime prevalence of LBP in unadjusted and adjusted models for body-mass-index, and depression, as well as interactions between female sex and age (

RESULTS

The mean age of the sample was 47.4 years (Standard Deviation = 16.5). The adjusted odds ratio (aOR) of the association between sex and LBP in the merged sample was 1.11 (95% Confidence Interval = 0.88-1.40), with 87.4% of the variance in the studied association explained by between-site heterogeneity (Q test; p = 0.001). Females had 2.37 (95% CI: 1.48-3.78) higher odds of LBP compared to their male co-twins in the Spanish sample (adjusted), but a sex association was not found in the Australian nor US samples.

CONCLUSIONS

We found no evidence of the association between sex and LBP in our merged sample. Between-population differences (i.e. cultural background or health system characteristics) are likely to be major factors leading to variation in the sex association with LBP when familial factors are accounted for.

SIGNIFICANCE

Our study of adult opposite-sex twin pairs found no evidence of an association between female sex and lifetime prevalence of low back pain after controlling for familial factors in the merged sample from Australia, Spain and USA, contrary to findings from previous studies of unrelated individuals. Our findings indicate potentially relevant between-country genetic, cultural and environmental differences which may need to be considered for optimal and individualized strategies for the prevention and management of low back pain across the lifespan.

Collapse

Key Words Collapse

MESH Headings Collapse

Grants Collapse

Affiliation(s)

Lucas Calais-Ferreira Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Victoria, Australia Centre for Adolescent Health, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
Daniel Pozzobon Biomechanics Laboratory, Sports and Physical Education Center, Federal University of Santa Maria, Santa Maria, Brazil
Marina B Pinheiro Institute for Musculoskeletal Health, The University of Sydney and Sydney Local Health District, Sydney, New South Wales, Australia Sydney School of Public Health, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
Fiona M Blyth Sydney School of Public Health, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
Juan R Ordoñana Department of Human Anatomy and Psychobiology, University of Murcia, Murcia, Spain Murcia Institute of Biomedical Research, IMIB-Arrixaca, Murcia, Spain
Glen E Duncan Department of Nutrition and Exercise Physiology, Elson S. Floyd College of Medicine, Washington State University Health Sciences Spokane, Washington, USA
John L Hopper Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Victoria, Australia
Paulo H Ferreira Musculoskeletal Research Hub, Charles Perkins Centre, School of Health Sciences, University of Sydney, Sydney, New South Wales, Australia
Manuela L Ferreira School of Health Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney Musculoskeletal Health, The Kolling Institute, Sydney, New South Wales, Australia

Collapse

Collaborators Collapse

Multi-Trait Exome-Wide Association Study of Back Pain-Related Phenotypes

Back pain (BP) is a major contributor to disability worldwide, with heritability estimated at 40-60%. However, less than half of the heritability is explained by common genetic variants identified by genome-wide association studies. More powerful methods and rare and ultra-rare variant analysis may offer additional insight. This study utilized exome sequencing data from the UK Biobank to perform a multi-trait gene-based association analysis of three BP-related phenotypes: chronic back pain, dorsalgia, and intervertebral disc disorder. We identified the SLC13A1 gene as a contributor to chronic back pain via loss-of-function (LoF) and missense variants. This gene has been previously detected in two studies. A multi-trait approach uncovered the novel FSCN3 gene and its impact on back pain through LoF variants. This gene deserves attention because it is only the second gene shown to have an effect on back pain due to LoF variants and represents a promising drug target for back pain therapy.

Heredity of pregnancy-related pelvic girdle pain in Sweden

INTRODUCTION

Pelvic girdle pain during and after pregnancy is a major public health problem with significant daily problems for affected women and their families. There is now accumulating evidence that pregnancy-related pelvic girdle pain originates from the sacroiliac joints and the pubic symphysis as well as their extra-articular ligaments. However, the heritability of the disease remains to be determined. We hypothesized that there is an increased familial risk of pregnancy-related pelvic girdle pain.

MATERIAL AND METHODS

A population-based national database linkage registry study of approximately 9.3 million individuals within 4.2 million families in Sweden with a recruitment period from 1997 to 2018. The Swedish Multi-generation register was used to find female pairs of twins, full siblings, half-siblings and first cousins where both in the pairs had a completed pregnancy. The outcome measure was diagnosis of pregnancy-related pelvic girdle pain (International Classification of Diseases-10 O26.7 [1997-2018]) in the first pregnancy. Data was obtained from the Swedish Hospital Discharge Register, the Swedish Outpatient Care Register, the Swedish Medical Birth Register, the Primary Healthcare Register, and Medical Treatment Register. Cox regression analysis was used to calculate adjusted estimated effect of the exposure variable familial history of pregnancy-related pelvic girdle pain on the outcome variable pregnancy-related pelvic girdle pain at first birth.

RESULTS

From the registers, 1 010 064 women pregnant with their first child within 795 654 families were collected. In total, 109 147 women were diagnosed with pregnancy-related pelvic girdle pain. The adjusted hazard ratio for a familial risk of pregnancy-related pelvic girdle pain was 2.09 (95% CI 1.85-2.37) among twins (monozygotic and dizygotic), 1.78 (95% CI 1.74-1.82) in full siblings, 1.16 (95% CI 1.06-1.28) in half-siblings from the mother, 1.09 (95% CI 1.024-1.16) in half-siblings from the father and 1.09 (95% CI 1.07-1.12) in first cousins.

CONCLUSIONS

This nationwide observational study showed a familial clustering of pregnancy-related pelvic girdle pain. The hazard ratio for the condition was associated with the degree of relatedness, suggesting that heredity factors contribute to the development of pregnancy-related pelvic girdle pain. There is no causal treatment available for pregnancy-related pelvic girdle pain and further studies are now encouraged to clarify the specific genetic factors that contribute to the disease and for future targeted interventions.

Development and Replication of a Genome-Wide Polygenic Risk Score for Chronic Back Pain

Chronic back pain (CBP) is a complex heritable trait and a major cause of disability worldwide. We developed and validated a genome-wide polygenic risk score (PRS) for CBP using a large-scale GWAS based on UK Biobank participants of European ancestry (N = 265,000). The PRS showed poor overall predictive ability (AUC = 0.56 and OR = 1.24 per SD, 95% CI: 1.22-1.26), but individuals from the 99th percentile of PRS distribution had a nearly two-fold increased risk of CBP (OR = 1.82, 95% CI: 1.60-2.06). We validated the PRS on an independent TwinsUK sample, obtaining a similar magnitude of effect. The PRS was significantly associated with various ICD-10 and OPCS-4 diagnostic codes, including chronic ischemic heart disease (OR = 1.1, p-value = 4.8 × 10^-15), obesity, metabolism-related traits, spine disorders, disc degeneration, and arthritis-related disorders. PRS and environment interaction analysis with twelve known CBP risk factors revealed no significant results, suggesting that the magnitude of G × E interactions with studied factors is small. The limited predictive ability of the PRS that we developed is likely explained by the complexity, heterogeneity, and polygenicity of CBP, for which sample sizes of a few hundred thousand are insufficient to estimate small genetic effects robustly.

Noncoding rare variants in PANX3 are associated with chronic back pain

ABSTRACT

Back pain is the leading cause of years lived with disability worldwide, yet surprisingly, little is known regarding the biology underlying this condition. The impact of genetics is known for chronic back pain: its heritability is estimated to be at least 40%. Large genome-wide association studies have shown that common variation may account for up to 35% of chronic back pain heritability; rare variants may explain a portion of the heritability not explained by common variants. In this study, we performed the first gene-based association analysis of chronic back pain using UK Biobank imputed data including rare variants with moderate imputation quality. We discovered 2 genes, SOX5 and PANX3 , influencing chronic back pain. The SOX5 gene is a well-known back pain gene. The PANX3 gene has not previously been described as having a role in chronic back pain. We showed that the association of PANX3 with chronic back pain is driven by rare noncoding intronic polymorphisms. This result was replicated in an independent sample from UK Biobank and validated using a similar phenotype, dorsalgia, from FinnGen Biobank. We also found that the PANX3 gene is associated with intervertebral disk disorders. We can speculate that a possible mechanism of action of PANX3 on back pain is due to its effect on the intervertebral disks.

Insights into the pleiotropic relationships between chronic back pain and inflammation-related musculoskeletal conditions: rheumatoid arthritis and osteoporotic abnormalities

ABSTRACT

The ageing process includes the development of debilitating musculoskeletal (MSK) conditions, including chronic back pain (CBP), rheumatoid arthritis (RA), and osteoporosis (OP). The mechanisms involved in the genetic-epidemiological relationships between these MSK phenotypes are controversial and limited and thus require clarification, in particular, between CBP and the other MSK phenotypes. A cross-sectional statistical analysis was conducted using Europeans from the UK Biobank data collection, including 73,794 CBP, 4883 RA, and 7153 OP cases as well as 242,216 calcaneus bone mineral density scores. C-reactive protein (CRP) was measured for 402,165 subjects in this sample. Genetic correlations were assessed to evaluate shared genetic background between traits. Mendelian randomization was performed to assess a causal relationship between CBP and RA and OP along with other risk factors, such as CRP. Colocalization analysis was conducted to identify shared pleiotropic regions between the examined traits. Bayesian modelling was performed to determine a potential pathway that may explain the interrelationships among these traits. Mendelian randomization analyses revealed that CRP causally predicts CBP only (β = 0.183, 95% CI = 0.077-0.290, P -value = 0.001). Horizontally pleiotropy appeared to explain the relationship between CBP and RA and OP. Through colocalization analysis, several genomic regions emerged describing common genetic influences between CBP and its proposed risk factors, including HLA-DQA1/HLA-DQB1, APOE , SOX5, and MYH7B as well as Histone 1 genes. We speculate that among other factors, CBP and its MSK comorbidities may arise from common inflammatory mechanisms. Colocalized identified genes may aid in advancing or improving the mode of treatment in patients with CBP.

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.

The association between chronic heart failure and frailty index: A study based on the National Health and Nutrition Examination Survey from 1999 to 2018

Objective

This study aims to explore the association between the frailty index and chronic heart failure (CHF).

Methods

We collected data from the National Health and Nutrition Examination Survey (NHANES) (1998-2018) database to assess the association between CHF and frailty. Demographic, inquiry, laboratory examinations, and characteristics were gathered to compare CHF and non-CHF groups. Multiple logistic regression analysis was performed to explore the relationship between frailty and CHF. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence interval (CI) for mortality from all causes and cardiovascular disease (CVD).

Results

A total of 16,175 participants with cardiac and cerebrovascular disease were categorized into CHF (n = 1,125) and non-CHF (n = 15,050) groups. In patients with CHF, the prevalence of frailty, pre-frailty, and non-frailty were 66.31, 30.93, and 2.75%, respectively. In multiple logistic regression, patients with CHF who were male (OR = 0.63, 95% CI: 3.11-5.22), whose annual family income was over $20,000 (OR = 0.52, 95% CI: 0.37-0.72, p < 0.001), or with normal hemoglobin level (OR = 0.77, 95% CI: 0.68-0.88, P < 0.001) had a lower likelihood of frailty. CHF patients with hypertension (OR = 3.60, 95% CI: 2.17-5.99, P < 0.0001), coronary heart disease (OR = 1.76, 95% CI: 1.10-2.84, P = 0.02), diabetes mellitus (OR = 1.89, 95% CI: 1.28-2.78, P < 0.001), and stroke (OR = 2.52, 95% CI: 1.53-4.15, P < 0.001) tended to be frail. Survival analysis suggested that pre-frailty and frailty were related to poor all-cause deaths (HR = 1.48, 95% CI: 1.36-1.66; HR = 2.77, 95% CI: 2.40-3.18) and CVD mortality (HR = 1.58, 95% CI: 1.26-1.97; HR = 2.55, 95% CI: 2.02-3.21). CHF patients with frailty were strongly connected with all-cause death (HR = 2.14, 95% CI: 1.27-3.62).

Conclusion

Frailty was positively associated with CHF. Patients with CHF who were male, whose annual family income was over $20,000, or with normal hemoglobin level were negatively correlated to frailty. For patients with cardiac and cerebrovascular disease as well as CHF, frailty was strongly connected with all-cause death.

Causal effects of psychosocial factors on chronic back pain: a bidirectional Mendelian randomisation study

PURPOSE

Risk factors for chronic back pain (CBP) may share underlying genetic factors, making them difficult to study using conventional methods. We conducted a bi-directional Mendelian randomisation (MR) study to examine the causal effects of risk factors (education, smoking, alcohol consumption, physical activity, sleep and depression) on CBP and the causal effect of CBP on the same risk factors.

METHODS

Genetic instruments for risk factors and CBP were obtained from the largest published genome-wide association studies (GWAS) of risk factor traits conducted in individuals of European ancestry. We used inverse weighted variance meta-analysis (IVW), Causal Analysis Using Summary Effect (CAUSE) and sensitivity analyses to examine evidence for causal associations. We interpreted exposure-outcome associations as being consistent with a causal relationship if results with IVW or CAUSE were statistically significant after accounting for multiple statistical testing (p < 0.003), and the direction and magnitude of effect estimates were concordant between IVW, CAUSE, and sensitivity analyses.

RESULTS

We found evidence for statistically significant causal associations between greater education (OR per 4.2 years of schooling = 0.54), ever smoking (OR = 1.27), greater alcohol consumption (OR = 1.29 per consumption category increase) and major depressive disorder (OR = 1.41) and risk of CBP. Conversely, we found evidence for significant causal associations between CBP and greater alcohol consumption (OR = 1.19) and between CBP and smoking (OR = 1.21). Other relationships did not meet our pre-defined criteria for causal association.

CONCLUSION

Fewer years of schooling, smoking, greater alcohol consumption, and major depressive disorder increase the risk of CBP. CBP increases the risk of greater alcohol consumption and smoking.

Nature and nurture. Genetic and environmental factors on the relationship between back pain and sleep quality

BACKGROUND

Chronic low back pain (LBP), neck pain (NP), and sleep quality (SQ) are genetically influenced. All three conditions frequently co-occur and shared genetic etiology on a pairwise base has been reported. However, to our knowledge no study has yet investigated if these three conditions are influenced by the same genetic and environmental factors and the extent and pattern of genetic overlap between them, hence the current research.

METHODS

The sample included 2134 participants. Lifetime prevalence of NP and LBP were assessed through a dichotomous self-reported question derived from the Spanish National Health Survey. SQ was measured using the Pittsburgh Sleep Quality Index Questionnaire. A common pathway model with sleep quality and back pain as latent factors was fitted.

RESULTS

Our results highlight that a latent back pain factor, including both NP and LBP, is explained by both genetic (41%) and environmental (59%) factors. There are also significant unique environmental factors for NP (33%) and LBP (37%) respectively. Yet, specific genetic factors were scant (9%) for NP and negligible for LBP (0%). Genetic and environmental factors affecting SQ only contribute with 3% and 5% of the variance, respectively, to the common latent back pain variable.

CONCLUSIONS

NP and LBP share most of their genetic variance, while environmental effects show greater specificity for each of the back pain locations. Associations with SQ were of a limited magnitude.

Association Between Family History of Surgically Treated Low Back Pain and Adolescent Low Back Pain

STUDY DESIGN

Cross-sectional.

OBJECTIVE

To study the associations between a family history of surgically treated low back pain (LBP) and adolescent LBP.

SUMMARY OF BACKGROUND DATA

A family history of LBP is related to adolescent LBP, but whether a family history of back surgery is relevant to adolescent LBP is not known.

METHODS

A subpopulation of the Northern Finland Birth Cohort 1986 was contacted when they were aged between 18 and 19years. The postal questionnaire asked the participants to report their LBP and a relative's (mother, father, sibling) LBP and back surgery, and to provide data on potential covariates. The association between a family history of LBP ("no family history of LBP," "family history of LBP but no surgery," and "family history of LBP and surgery") and adolescent LBP (no LBP, occasional LBP, and frequent LBP) were evaluated using logistic regression analysis with odds ratios (ORs) and 95% confidence intervals (CIs), adjusted for sex, smoking, and psychological distress.

RESULTS

Of the 1374 adolescents in the study, 33% reported occasional LBP and 9% frequent LBP. Both the "family history of LBP but no surgery" and "family history of LBP and surgery" categories were associated with frequent LBP (adjusted OR [aOR] 2.09, 95% CI 1.38-3.16; aOR 2.23, 95% CI 1.02-4.90, respectively). Occasional LBP was associated with the "family history of LBP and surgery" category. A subgroup analysis of adolescents with a family history of LBP found no statistically significant associations between family history of back surgery and adolescent LBP.

CONCLUSION

Our findings suggest that adolescents who report a family history of LBP have higher odds of frequent LBP irrespectively of a family history of back surgery.Level of evidence: 4.

Neck pain: global epidemiology, trends and risk factors

BACKGROUND

Neck pain is one of the most common musculoskeletal disorders, having an age-standardised prevalence rate of 27.0 per 1000 population in 2019. This literature review describes the global epidemiology and trends associated with neck pain, before exploring the psychological and biological risk factors associated with the initiation and progression of neck pain.

METHODS

The PubMed database and Google Scholar search engine were searched up to May 21, 2021. Studies were included that used human subjects and evaluated the effects of biological or psychological factors on the occurrence or progression of neck pain, or reported its epidemiology.

RESULTS

Psychological risk factors, such as long-term stress, lack of social support, anxiety, and depression are important risk factors for neck pain. In terms of the biological risks, neck pain might occur as a consequence of certain diseases, such as neuromusculoskeletal disorders or autoimmune diseases. There is also evidence that demographic characteristics, such as age and sex, can influence the prevalence and development of neck pain, although further research is needed.

CONCLUSIONS

The findings of the present study provide a comprehensive and informative overview that should be useful for the prevention, diagnosis, and management of neck pain.

Investigating the Causal Relationship Between Physical Activity and Chronic Back Pain: A Bidirectional Two-Sample Mendelian Randomization Study

Background: Recent observational studies have reported a negative association between physical activity and chronic back pain (CBP), but the causality of the association remains unknown. We introduce bidirectional Mendelian randomization (MR) to assess potential causal inference between physical activity and CBP. Materials and Methods: This two-sample MR used independent genetic variants associated with physical activity and CBP as genetic instruments from large genome-wide association studies (GWASs). The effects of both directions (physical activity to CBP and CBP to physical activity) were examined. Inverse variance-weighted meta-analysis and alternate methods (weighted median and MR-Egger) were used to combine the MR estimates of the genetic instruments. Multiple sensitivity analyses were conducted to examine the robustness of the results. Results: The MR set parallel GWAS cohorts, among which, those involved in the primary analysis were comprised of 337,234 participants for physical activity and 158,025 participants (29,531 cases) for CBP. No evidence of a causal relationship was found in the direction of physical activity to CBP [odds ratio (OR), 0.98; 95% CI, 0.85-1.13; p = 0.81]. In contrast, a negative causal relationship in the direction of CBP to physical activity was detected (β = -0.07; 95% CI, -0.12 to -0.01; p = 0.02), implying a reduction in moderate-vigorous physical activity (approximately 146 MET-minutes/week) for participants with CBP relative to controls. Conclusion: The negative relationship between physical activity and CBP is probably derived from the reduced physical activity of patients experiencing CBP rather than the protective effect of physical activity on CBP.

Heritability of musculoskeletal pain and pain sensitivity phenotypes: two generations of the Raine Study

ABSTRACT

There is a need to better understand biological factors that increase the risk of persistent musculoskeletal pain and heightened pain sensitivity. Knowing the heritability (how genes account for differences in people's traits) can enhance the understanding of genetic versus environmental influences of pain and pain sensitivity. However, there are gaps in current knowledge, including the need for intergenerational studies to broaden our understanding of the genetic basis of pain. Data from Gen1 and Gen2 of the Raine Study were used to investigate the heritability of musculoskeletal pain, and pressure and cold pain sensitivity. Participants included parents (Gen 1, n=1092) and their offspring (Gen 2, n=688) who underwent a battery of testing and questionnaires including pressure and cold pain threshold testing and assessments of physical activity, sleep, musculoskeletal pain, mental health and adiposity. Heritability estimates were derived using the Sequential Oliogenic Linkage Analysis Routines (SOLAR) software. Heritability estimates for musculoskeletal pain and pressure pain sensitivity were significant, accounting for between 0.190 and 0.289 of the variation in the phenotype. In contrast, heritability of cold pain sensitivity was not significant. This is the largest intergenerational study to date to comprehensively investigate the heritability of both musculoskeletal pain and pain sensitivity, using robust statistical analysis. This study provides support for the heritability of musculoskeletal pain and pain sensitivity to pressure, suggesting the need for further convergence of genetic and environmental factors in models for the development and/or maintenance of these pain disorders.

Identification of DNA methylation associated enrichment pathways in adults with non-specific chronic low back pain

Chronic low back pain (cLBP) that cannot be attributable to a specific pathoanatomical change is associated with high personal and societal costs. Still, the underlying mechanism that causes and sustains such a phenotype is largely unknown. Emerging evidence suggests that epigenetic changes play a role in chronic pain conditions. Using reduced representation bisulfite sequencing (RRBS), we evaluated DNA methylation profiles of adults with non-specific cLBP (n = 50) and pain-free controls (n = 48). We identified 28,325 hypermethylated and 36,936 hypomethylated CpG sites (p < 0.05). After correcting for multiple testing, we identified 159 DMRs (q < 0.01and methylation difference > 10%), the majority of which were located in CpG island (50%) and promoter regions (48%) on the associated genes. The genes associated with the differentially methylated regions were highly enriched in biological processes that have previously been implicated in immune signaling, endochondral ossification, and G-protein coupled transmissions. Our findings support inflammatory alterations and the role of bone maturation in cLBP. This study suggests that epigenetic regulation has an important role in the pathophysiology of non-specific cLBP and a basis for future studies in biomarker development and targeted interventions.

Sex differences in genetic and environmental influences on frailty and its relation to body mass index and education

Frailty is influenced by numerous genetic and environmental factors. However, sex differences in how these factors affect frailty, and the gene-environment interplay among frailty and two of its well-established risk factors, unhealthy body mass index (BMI) and low education, are less clear. In a large sample of 42,994 Swedish twins, we used structural equation models to estimate the genetic (heritability) and environmental sources of variance in frailty, defined as the frailty index (FI), separately in men and women. Genetic and individual-specific environmental factors contributed approximately equally to the FI variance. The heritability of FI was slightly, but significantly, higher in women (52%) than in men (45%), yet we found only weak-to-no indication of different sources of genetic variance influencing frailty across sexes. We observed a small-to-moderate genetic overlap between FI and BMI, and that the correlation between FI and education was largely explained by environmental factors common to twins in a pair. Additionally, genetic factors accounted for more of FI variation at both low and high BMI levels, with similar patterns in both sexes. In conclusion, the twin-based heritability of frailty is higher in women than in men, and different mechanisms may underlie the associations of frailty with BMI and education.

Number of Pain Locations as a Predictor of Cause-Specific Disability Pension in Sweden-Do Common Mental Disorders Play a Role?

OBJECTIVE

The aim of this study was to investigate the associations between number of pain locations, common mental disorders (CMDs), and disability pension (DP).

METHODS

Survey data in 1998 to 2003 for 27,165 Swedish twins born in 1935 to 1958 were linked to national DP data until 2013. Pain locations were evaluated for back, low back, sciatica, shoulder, or neck pain, and CMDs for lifetime major depression and 1-month anxiety.

RESULTS

The number of pain locations was associated with DP in a dose-response manner. One pain location had a hazard ratio of 1.50 (95% confidence interval 1.35 to 1.68) and five pain locations hazard ratio 4.67 (95% confidence interval 4.11 to 5.30) for DP. Also, CMDs were associated with DP.

CONCLUSION

The number of pain locations has a dose-response association with the risk of DP. CMDs predict DP. In strategies to prevent DP, early signs of pain or CMDs should be taken into consideration.

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.

Potential risk factors and triggers for back pain in children and young adults. A scoping review, part II: unclear or mixed types of back pain

Background

Back pain is a global problem in terms of disability and financially, with a large burden both to the individual and to society. Back pain was previously believed to be uncommon in children. However, there is a growing body of evidence that this is not the case.

Objective

Part I of this scoping review studied risk factors of incident and episodic back pain. In this part II we aimed to identify all risk factors and triggers with unclear or mixed type back pain in young people and to identify any gaps in the literature.

Methods

A scoping review design was selected to summarise the evidence, as there are many studies on "risk factors" for back pain. The scoping review followed the PRISMSA-ScR guidelines. We considered all studies that tested potential risk factors and triggers for thoracic and/or lumbar spine pain, in children, adolescents, and young adults (≤ 24 years). PubMed and Cochrane databases were searched from inception to September 2018, to identify relevant English language articles. The results regarding potential risk factors were separated into temporal precursors and bidirectional risk factors and the studies were classified by study design.

Results

Our comprehensive search strategy identified 7356 articles, of which 83 articles were considered eligible for this review (part II). There were 53 cross-sectional studies and 30 cohort studies. Potential risk factors for back pain were: female sex, older age, later pubertal status, positive family history of back pain, increased growth, and a history of back pain, most of which are temporal precursor variables. There was limited research for the illness factors, spinal posture, and muscle endurance in the development of back pain.

Conclusion

Many of the included studies approached risk factors in similar ways and found factors that were associated with back pain but were not obvious risk factors as causality was uncertain. Future research should be more rigorous and innovative in the way that risk factors are considered. This could be through statistical approaches including cumulative exposures, or longitudinal approaches including multi-trajectory methods. Additionally, data on proposed risk factors should be collected before the onset of back pain.

OPRM1 rs1799971, COMT rs4680, and FAAH rs324420 genes interact with placebo procedures to induce hypoalgesia

Genetics studies on the placebo hypoalgesic effect highlight a promising link between single nucleotide polymorphisms (SNPs) in the dopamine, opioid, and endocannabinoid genes and placebo hypoalgesia. However, epistasis and replication studies are missing. In this study, we expanded on previous findings related to the 3 SNPs in the opioid receptor mu subunit (OPRM1 rs1799971), catechol-O-methyltransferase (COMT rs4680), and fatty acid amide hydrolase (FAAH rs324420) genes associated with placebo hypoalgesia and tested the effect of a 3-way interaction on placebo hypoalgesia. Using 2 well-established placebo procedures (verbal suggestion and learning paradigm), we induced significant placebo hypoalgesic effects in 160 healthy participants. We found that individuals with OPRM1 AA combined with FAAH Pro/Pro and those carrying COMT met/met together with FAAH Pro/Pro showed significant placebo effects. Participants with COMT met/val alleles showed significant placebo effects independently of OPRM1 and FAAH allele combinations. Finally, the model that included the placebo procedure and genotypes predicted placebo responsiveness with a higher accuracy (area under the curve, AUC = 0.773) as compared to the SNPs alone indicating that genetic variants can only partially explain the placebo responder status. Our results suggest that the endogenous mu-opioid system with a larger activation in response to pain in the met/val allele carriers as well as the synergism between endogenous mu-opioid system and cannabinoids might play the most relevant role in driving hypoalgesic responses. Future epistasis studies with larger sample sizes will help us to fully understand the complexity of placebo effects and explain the mechanisms that underlie placebo responsiveness.

Targeting Neuropathic Pain: Pathobiology, Current Treatment and Peptidomimetics as a New Therapeutic Opportunity

There is a huge need for pharmaceutical agents for the treatment of chronic Neuropathic Pain (NP), a complex condition where patients can suffer from either hyperalgesia or allodynia originating from central or peripheral nerve injuries. To date, the therapeutic guidelines include the use of tricyclic antidepressants, serotonin-noradrenaline reuptake inhibitors and anticonvulsants, beside the use of natural compounds and non-pharmacological options. Unfortunately, these drugs suffer from limited efficacy and serious dose-dependent adverse effects. In the last decades, the heptapeptide SP1-7, the major bioactive metabolite produced by Substance P (SP) cleavage, has been extensively investigated as a potential target for the development of novel peptidomimetic molecules to treat NP. Although the physiological effects of this SP fragment have been studied in detail, the mechanism behind its action is not fully clarified and the target for SP1-7 has not been identified yet. Nevertheless, specific binding sites for the heptapeptide have been found in brain and spinal cord of both mouse and rats. Several Structure-Affinity Relationship (SAR) studies on SP1-7 and some of its synthetic analogues have been carried out aiming to developing more metabolically stable and effective small molecule SP1-7-related amides that could be used as research tools for a better understanding of the SP1-7 system and, in a longer perspective, as potential therapeutic agents for future treatment of NP.

The profile of chiropractors managing patients with low back-related leg pain: analyses of 1907 chiropractors from the ACORN practice-based research network

Background

Approximately 60% of people with low back pain also have associated leg pain symptoms. Guidelines for low back pain recommend non-pharmacological approaches, including spinal manipulation - a therapy provided by chiropractors. However, limited empirical data has examined the characteristics of chiropractors managing patients with low back-related leg pain (LBRLP). Our objective is to describe the prevalence, profile and practice characteristics of Australian chiropractors who often treat LBRLP, compared to those who do not often treat LBRLP.

Methods

This is a cross-sectional analysis of a nationally representative sample from the Australian Chiropractic Research Network (ACORN). This study investigated the demographic and practice characteristics as well as clinical management of chiropractors who ‘often’ treated patients with LBRLP compared to those who treated LBRLP ‘never/rarely/sometimes’. Multiple logistic regression models identified independent factors associated with chiropractors who ‘often’ treated patients with LBRLP.

Results

A total of 1907 chiropractors reported treating patients experiencing LBRLP, with 80.9% of them ‘often’ treating LBRLP. Chiropractors who ‘often’ treated LBRLP were more likely to manage patients with multi-site pain including axial low back pain (OR = 21.1), referred/radicular neck pain (OR = 10.8) and referred/radicular thoracic pain (OR = 3.1). While no specific management strategies were identified, chiropractors who ‘often’ treated LBRLP were more likely to discuss medication (OR = 1.8), manage migraine (OR = 1.7) and degenerative spine conditions (OR = 1.5), and treat women during pregnancy (OR = 1.6) and people with work-related injuries (OR = 1.5), compared to those not treating LBRLP frequently.

Conclusions

Australian chiropractors frequently manage LBRLP, although the nature of specific management approaches for this condition remains unclear. Further research on the management of LBRLP can better inform policy makers and educators interested in upskilling chiropractors to deliver safe and effective treatment of LBRLP.

Do medical conditions predispose to the development of chronic back pain? A longitudinal co-twin control study of middle-aged males with 11-year follow-up

BACKGROUND

Poor general health predicts the transition to chronic back pain (CBP), but the role of specific medical conditions in the development of CBP is unclear. The study aim was to examine the association of medical conditions with the development of CBP ("incident CBP"), while controlling for familial factors, including genetics.

METHODS

This was a longitudinal co-twin control study conducted in a nationwide United States sample from the Vietnam Era Twin Registry. The study sample included 3045 males without back problems at baseline, including 662 complete twin pairs, who were followed for 11 years. Baseline surveys inquired about self-reported medical conditions (arthritis, diabetes, hypertension, and coronary artery disease [CAD]). A medical comorbidity score was calculated based on the presence and/or treatment of 8 medical conditions. Covariates included age, race, and education. At 11-year follow-up, participants reported ever having had CBP. Odds ratios (ORs) and 95% confidence intervals (CI) were estimated when considering twins as individuals, and in matched-pair co-twin control analyses adjusting for familial/genetic factors.

RESULTS

Mean age at baseline was 51 years and 17% of participants developed CBP over the 11-year follow-up. Arthritis was significantly associated with incident CBP in individual-level analysis (OR 1.8 [95% CI 1.4-2.2]), but not within-pair analysis (OR 0.9 [95% CI 0.4-1.9]. CAD (OR 1.6 [95% CI 1.0-2.3]), hypertension (OR 1.3 [95% CI 1.0-1.5]), and the medical comorbidity score (OR 1.2 [95%CI 1.1-2.2]) were significantly associated with incident CBP in individual-level analyses; associations in within-pair analyses were of comparable magnitude, but not statistically significant. Diabetes was not associated with incident CBP.

CONCLUSIONS

Arthritis, hypertension, CAD, and medical comorbidity score were associated with incident CBP in the current study. However, the association between arthritis and incident CBP was confounded by familial factors. This suggests that prevention or treatment of arthritis is unlikely to be useful for CBP prevention. Our findings cannot exclude the possibility of causal associations between CAD, hypertension, and medical comorbidities and incident CBP.

Genome-wide meta-analysis of 158,000 individuals of European ancestry identifies three loci associated with chronic back pain

Back pain is the #1 cause of years lived with disability worldwide, yet surprisingly little is known regarding the biology underlying this symptom. We conducted a genome-wide association study (GWAS) meta-analysis of chronic back pain (CBP). Adults of European ancestry were included from 15 cohorts in the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) consortium, and from the UK Biobank interim data release. CBP cases were defined as those reporting back pain present for ≥3-6 months; non-cases were included as comparisons ("controls"). Each cohort conducted genotyping using commercially available arrays followed by imputation. GWAS used logistic regression models with additive genetic effects, adjusting for age, sex, study-specific covariates, and population substructure. The threshold for genome-wide significance in the fixed-effect inverse-variance weighted meta-analysis was p<5×10(-8). Suggestive (p<5×10(-7)) and genome-wide significant (p<5×10(-8)) variants were carried forward for replication or further investigation in the remaining UK Biobank participants not included in the discovery sample. The discovery sample comprised 158,025 individuals, including 29,531 CBP cases. A genome-wide significant association was found for the intronic variant rs12310519 in SOX5 (OR 1.08, p = 7.2×10(-10)). This was subsequently replicated in 283,752 UK Biobank participants not included in the discovery sample, including 50,915 cases (OR 1.06, p = 5.3×10(-11)), and exceeded genome-wide significance in joint meta-analysis (OR 1.07, p = 4.5×10(-19)). We found suggestive associations at three other loci in the discovery sample, two of which exceeded genome-wide significance in joint meta-analysis: an intergenic variant, rs7833174, located between CCDC26 and GSDMC (OR 1.05, p = 4.4×10(-13)), and an intronic variant, rs4384683, in DCC (OR 0.97, p = 2.4×10(-10)). In this first reported meta-analysis of GWAS for CBP, we identified and replicated a genetic locus associated with CBP (SOX5). We also identified 2 other loci that reached genome-wide significance in a 2-stage joint meta-analysis (CCDC26/GSDMC and DCC).

What low back pain is and why we need to pay attention

Low back pain is a very common symptom. It occurs in high-income, middle-income, and low-income countries and all age groups from children to the elderly population. Globally, years lived with disability caused by low back pain increased by 54% between 1990 and 2015, mainly because of population increase and ageing, with the biggest increase seen in low-income and middle-income countries. Low back pain is now the leading cause of disability worldwide. For nearly all people with low back pain, it is not possible to identify a specific nociceptive cause. Only a small proportion of people have a well understood pathological cause-eg, a vertebral fracture, malignancy, or infection. People with physically demanding jobs, physical and mental comorbidities, smokers, and obese individuals are at greatest risk of reporting low back pain. Disabling low back pain is over-represented among people with low socioeconomic status. Most people with new episodes of low back pain recover quickly; however, recurrence is common and in a small proportion of people, low back pain becomes persistent and disabling. Initial high pain intensity, psychological distress, and accompanying pain at multiple body sites increases the risk of persistent disabling low back pain. Increasing evidence shows that central pain-modulating mechanisms and pain cognitions have important roles in the development of persistent disabling low back pain. Cost, health-care use, and disability from low back pain vary substantially between countries and are influenced by local culture and social systems, as well as by beliefs about cause and effect. Disability and costs attributed to low back pain are projected to increase in coming decades, in particular in low-income and middle-income countries, where health and other systems are often fragile and not equipped to cope with this growing burden. Intensified research efforts and global initiatives are clearly needed to address the burden of low back pain as a public health problem.

Chronic pain in families: a cross-sectional study of shared social, behavioural, and environmental influences

Chronic pain is common and creates a significant burden to the individual and society. Emerging research has shown the influence of the family environment on pain outcomes. However, it is not clear what shared factors between family members associate with chronic pain. This study aimed to investigate the family-level contribution to an individual's chronic pain status. This was a cross-sectional study using the Generation Scotland: Scottish Family Health Study data set. This study focused on a nested cohort of dyads (only 2 relatives per family, n = 2714). Multi-level modelling was first performed to estimate the extent of variance in chronic pain at the family level. Then each member of the dyad was randomly assigned as either the exposure or outcome family member, and logistic regression was used to identify shared factors associated with the outcome of chronic pain status. Multi-level modelling showed just under 10% of variation in chronic pain status was at a family level. There was an increase in odds of chronic pain if exposure family member had chronic pain (odds ratio [OR]: 1.30, 95% confidence interval [CI]: 1.02-1.65), if both were women (OR: 1.39, 95% CI: 0.99-1.94), if both were older in age (OR: 1.80, 95% CI: 1.31-2.48), and if both had low household income (OR: 3.27, 95% CI: 1.72-6.21). These findings show that most explanation for chronic pain is still at the individual level. However, some significant shared effects between family members associate with chronic pain, and this highlights the influence of the family context.

Night work as a risk factor for future cause-specific disability pension: A prospective twin cohort study in Sweden

The objectives of the study were to investigate the associations between night work and disability pension (DP) due to all causes, cardiovascular (CVD), mental, and other diagnoses, adjusting for familial confounding. The material of the study included comprehensive survey data on 27 165 Swedish twins born in 1935-1958 that were linked with DP data for the survey period (1998-2003) to 2013. Night work was assessed as years of working nights at least every now and then, and categorized into not at all, 1-10 years and over 10 years. For statistical analyses, Cox proportional hazards regressions were used to calculate hazard ratios (HRs) with 95% confidence intervals (CIs). The results of the study indicated that over 10 years duration of night work had an age- and sex-adjusted HR of 1.48 (95% CI 1.11-1.98) for DP due to CVD and 1-10 years of night work an HR of 1.28 (95% CI 1.06-1.55) for DP due to mental diagnoses, but attenuated when covariates were adjusted for. Both 1-10 years (HR 1.27, 95% CI 1.17-1.39) and >10 years of night work (HR 1.20, 95% CI 1.08-1.34) were associated with DP due to all causes and other diagnoses. These risks remained after adjusting for covariates. To conclude, even modest exposure in terms of duration of night work is a risk factor for all-cause DP, but also for DP due to mental and other diagnoses. The risk of DP due to CVD seems to be associated with longer (>10 years) periods of night work. All the associations between night work and DP seem to be influenced by various covariates.

Does educational attainment increase the risk of low back pain when genetics are considered? A population-based study of Spanish twins

BACKGROUND CONTEXT

There is limited research investigating educational attainment as a risk factor for low back pain (LBP), with the influence of gender commonly being neglected. Furthermore, genetics and early shared environment explain a substantial proportion of LBP cases and need to be controlled for when investigating risk factors for LBP.

PURPOSE

To investigate whether educational attainment affects the prevalence and risk of LBP differently in men and women while controlling for the influence of genetics and early shared environment.

STUDY DESIGN

This is a cross-sectional and prospective twin case-control study.

PATIENT SAMPLE

Adult monozygotic (MZ) and dizygotic (DZ) twins from the Murcia Twin Registry, with available data on educational attainment, formed the base sample for this study. The prevalence analysis considered twins with available data on LBP in 2013 (n=1,580). The longitudinal analysis considered twins free of LBP at baseline (2009-2011), with available data on LBP at follow-up (2013) (n=1,077).

OUTCOME MEASURES

Data on the lifetime prevalence of activity limiting LBP (outcome) and educational attainment (risk factor) were self-reported.

METHODS

The prevalence analysis investigated the cross-sectional association between educational attainment and LBP, whereas the longitudinal analysis investigated whether educational attainment increased the risk of developing LBP. Both analyses were performed in the following sequence. First, a total sample analysis was performed on all twins (considering them as individuals), adjusting for confounding variables selected by the data. Second, to control for the influence of genetics and early shared environment, a within-pair case-control analysis (stratified by zygosity) was performed on complete twin pairs discordant for LBP (ie, one twin had LBP, whereas the co-twin did not). All analyses were stratified for gender where possible, with an interaction term determining whether gender was a significant moderator of the association between educational attainment and LBP.

RESULTS

Women with either general secondary or university education were less likely to experience (prevalence analysis) or to develop LBP (longitudinal analysis). Educational attainment did not affect the risk of LBP in men. When controlling for the effects of genetics and early shared environment, the relationship between educational status and LBP in women was no longer statistically significant.

CONCLUSIONS

Educational attainment affects LBP differently in men and women, with higher levels of education only decreasing the risk of developing LBP in women. After adjusting for genetics and early shared environment, the relationship between educational attainment and LBP in women disappears. This suggests that genetics and early shared environment are confounding the relationship between educational attainment and LBP in women.

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.

Video-game based exercises for older people with chronic low back pain: a protocol for a feasibility randomised controlled trial (the GAMEBACK trial)

OBJECTIVES

To investigate the feasibility of implementing a video-game exercise programme for older people with chronic low back pain (LBP).

DESIGN

Single-centred single-blinded randomised controlled trial (RCT).

SETTING

Physiotherapy outpatient department in a public hospital in Western Sydney, Australia.

PARTICIPANTS

We will recruit 60 participants over 55 years old with chronic LBP from the waiting list.

INTERVENTIONS

Participants will be randomised to receive video-game exercise (n=30) or to remain on the waiting list (n=30) for 8 weeks, with follow up at 3 and 6 months. Participants engaging in video-game exercises will be unsupervised and will complete video-game exercise for 60minutes, 3 times per week. Participants allocated to remain on the waiting list will be encouraged to maintain their usual levels of physical activity.

MAIN OUTCOME MEASURE

The primary outcomes for this feasibility study will be study processes (recruitment and response rates, adherence to and experience with the intervention, and incidence of adverse events) relevant to the future design of a large RCT. Estimates of treatment efficacy (point estimates and 95% confidence intervals) on pain self-efficacy, care seeking, physical activity, fear of movement/re-injury, pain, physical function, disability, falls-efficacy, strength, and walking speed, will be our secondary outcome measures.

RESULTS

Recruitment for this trial began in November 2015.

CONCLUSION

This study describes the rationale and processes of a feasibility study investigating a video-game exercise programme for older people with chronic LBP. Results from the feasibility study will inform on the design and sample required for a large multicentre RCT.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry: ACTRN12615000703505.

Sick leave and healthcare utilisation in women reporting pregnancy related low back pain and/or pelvic girdle pain at 14 months postpartum

BACKGROUND

Pregnancy related low back pain (PLBP) and pelvic girdle pain (PGP) are considered common complications of pregnancy. The long-term consequences for women with persistent PLBP/PGP postpartum are under-investigated. The main objective was to investigate the prevalence, pattern and degree of sick leave as well as healthcare utilisation and its perceived effect in women with persistent PLBP/PGP at 12 months postpartum.

METHOD

This is a follow-up study of a cohort involving of a sample of women, who delivered from January 1(st) 2002 to April 30(th) in 2002 at Umeå University Hospital and Sunderby Hospital, and who reported PLBP/PGP during pregnancy. A total of 639 women were followed-up by a second questionnaire (Q2) at approximately 6 months postpartum. Women with persistent PLBP/PGP at the second questionnaire (N = 200) were sent a third questionnaire (Q3) at approximately 12 months postpartum.

RESULTS

The final study sample consisted of 176 women reporting PLBP/PGP postpartum where N = 34 (19.3 %) reported 'no' pain, N = 115 (65.3 %) 'recurrent' pain, and N = 27 (15.3 %) 'continuous' pain. The vast majority (92.4 %) of women reported that they had neither been on sick leave nor sought any healthcare services (64.1 %) during the past 6 months at Q3. Women with 'continuous' pain at Q3 reported a higher extent of sick leave and healthcare seeking behaviour compared to women with 'recurrent' pain at Q3. Most women with persistent PLBP/PGP had been on sick leave on a full-time basis. The most commonly sought healthcare was physiotherapy, followed by consultation with a medical doctor, acupuncture and chiropractic.

CONCLUSION

Most women did not report any sick leave or sought any healthcare due to PLBP/PGP the past 6 months at Q3. However, women with 'continuous' PLBP/PGP 14 months postpartum did report a higher prevalence and degree of sick leave and sought healthcare to a higher extent compared to women with 'recurrent' PLBP/PGP at Q3. Women with more pronounced symptoms might constitute a specific subgroup of patients with a less favourable long-term outcome, thus PLBP/PGP needs to be addressed early in pregnancy to reduce both individual suffering and the risk of transition into chronicity.

Pharmacogenetics of analgesic drugs

• Individual variability in pain perception and differences in the efficacy of analgesic drugs are complex phenomena and are partly genetically predetermined.

• Analgesics act in various ways on the peripheral and central pain pathways and are regarded as one of the most valuable but equally dangerous groups of medications.

• While pharmacokinetic properties of drugs, metabolism in particular, have been scrutinised by genotype–phenotype correlation studies, the clinical significance of inherited variants in genes governing pharmacodynamics of analgesics remains largely unexplored (apart from the µ-opioid receptor).

• Lack of replication of the findings from one study to another makes meaningful personalised analgesic regime still a distant future.

• This narrative review will focus on findings related to pharmacogenetics of commonly used analgesic medications and highlight authors’ views on future clinical implications of pharmacogenetics in the context of pharmacological treatment of chronic pain.

Neck/upper back and low back pain in parents and their adult offspring: Family linkage data from the Norwegian HUNT Study

BACKGROUND

Chronic pain in the neck and low back is highly prevalent. Although heritable components have been identified, knowledge about generational transmission of spinal pain between parents and their adult offspring is sparse.

METHODS

This study examined the intergenerational association of spinal pain using data from 11,081 parent-offspring trios participating in the population-based HUNT Study in Norway. Logistic regression was used to calculate adjusted odds ratios (ORs) with 95% confidence intervals (CIs) for offspring spinal pain associated with parental spinal pain.

RESULTS

In total, 3654 (33%) offspring reported spinal pain at participation. Maternal and paternal spinal pain was consistently associated with higher ORs for offspring spinal pain. The results suggest a slightly stronger association for parental multilevel spinal pain (i.e., both neck/upper back pain and low back pain) than for pain localized to the neck/upper back or low back. Multilevel spinal pain in both parents was associated with ORs of 2.6 (95% CI, 2.1-3.3), 2.4 (95% CI, 1.9-3.1) and 3.1 (95% CI, 2.2-4.4) for offspring neck/upper back, low back and multilevel spinal pain, respectively.

CONCLUSION

Parental chronic spinal pain was consistently associated with increased occurrence of chronic spinal pain in their adult offspring, and this association was particularly strong for multilevel spinal pain.

Parental chronic pain in relation to chronic pain in their adult offspring: family-linkage within the HUNT Study, Norway

Background

Little is known about the association between parental chronic musculoskeletal pain (CMP) and occurrence of CMP in the adult offspring. The main objective of this study was to assess the parent-offspring association of CMP, and also to examine possible modifying effects of age and sex.

Methods

The study includes 11 248 parent-offspring trios from the Norwegian HUNT Study with information on parental CMP obtained in 1995–97 and offspring CMP obtained in 2006–08. Logistic regression was used to calculate adjusted odds ratios (ORs) for offspring CMP associated with parental CMP.

Results

Maternal and paternal CMP was associated with 20-40% increased odds of CMP in sons and daughters. Both sons and daughters had an OR of 1.6 (95% CI 1.4 to 1.9) when both parents reported CMP, compared to when none of the parents had CMP. Restricting the analyses to parental CMP that was associated with limited work ability and leisure time activity did not change the strength of the association. Further, analyses stratified by parental age ±65 years showed no clear difference in the estimated associations, and there was no evidence of interaction for parental sex (P ≥ 0.39) or offspring age ±40 years (P ≥ 0.26).

Conclusions

This large family-linkage study show that maternal and paternal CMP are positively associated with CMP in the adult offspring, irrespective of parental and offspring age, and that the associations are strongest when both parents have CMP. Although the high prevalence of CMP in both parents and offspring suggests that not all cases are clinically relevant, the results suggest that chronic pain has a heritable component.

Physical work load and psychological stress of daily activities as predictors of disability pension due to musculoskeletal disorders

Aims: Physical work loading and psychological stress commonly co-occur in working life, hence potentially having an interrelationship that may affect work incapacity. This prospective cohort study aimed to investigate the effect of stability and change in physical work loading and stress on the risk of disability pension (DP) due to musculoskeletal diagnoses (MSD), while accounting for familial confounding in these associations. Methods: Data on 12,455 twins born before 1958 were surveyed of their physical work loading and psychological stress of daily activities in 1975 and 1981. The follow-up data was collected from pension registers until 2004. Cox proportional hazards regression models were used. Results: During the follow up, 893 participants were granted DP due to MSD. Stable high (hazard ratio, HR, 2.21), but also increased physical work loading (HR 2.05) and high psychological stress (HR 2.22) were associated with increased risk for DP, and had significant interaction ( p=0.032). The associations were confirmed when accounting for several confounding factors. Conclusions:Stable high but also increased physical work loading and psychological stress of daily activities between two timepoints with 6 years apart confirms their predictive role for an increased risk of DP. Both physical work loading and psychological stress seem to be independent from various confounding factors hence suggesting direct effect on risk for DP providing potential for occupational health care to early identification of persons at risk.

Persistent smoking as a predictor of disability pension due to musculoskeletal diagnoses: a 23 year prospective study of Finnish twins

OBJECTIVE

To investigate whether stability or changes in smoking predict disability pension (DP) due to low back diagnoses (LBD) and musculoskeletal diagnoses (MSD) after taking familial confounding into account using a co-twin design.

METHOD

Longitudinal smoking patterns and multiple covariates in a population-based cohort of 17,451 Finnish twins (6959 complete pairs) born before 1958 were surveyed through questionnaires in 1975 and 1981. The outcome data were collected from the national pension registers until the end of 2004. Cox proportional hazards regression models were used for statistical analyses.

RESULTS

Disability pension due to low back diagnoses was granted to 408 individuals and disability pension due to musculoskeletal diagnoses to 1177 individuals during the follow-up of 23 years. Being a persistent smoker (current smoker both 1975 and 1981) predicted a significantly increased risk for disability pension (hazard ratio 1.69, 95% confidence interval 1.46, 1.97) compared to those individuals who had never smoked. The association remained when several confounding factors, including familial factors, were taken into account.

CONCLUSION

Persistent smoking predicts early disability pension due to musculoskeletal diagnoses and low back diagnoses independently from numerous confounding factors, including familial effects shared by the co-twins.

Twenty-five years with the biopsychosocial model of low back pain-is it time to celebrate? A report from the twelfth international forum for primary care research on low back pain

STUDY DESIGN

An integrated review of current knowledge about the biopsychosocial model of back pain for understanding etiology, prognosis, and interventions, as presented at the plenary sessions of the XII International Forum on LBP Research in Primary Care (Denmark; October 17-19, 2012).

OBJECTIVE

To evaluate the utility of the model in reference to rising rates of back pain-related disability, by identifying (a) the most promising avenues for future research in biological, psychological, and social approaches, (b) promising combinations of all 3 approaches, and (c) obstacles to effective implementation of biopsychosocial-based research and clinical practice.

SUMMARY OF BACKGROUND DATA

The biopsychosocial model of back pain has become a dominant model in the conceptualization of the etiology and prognosis of back pain, and has led to the development and testing of many interventions. Despite this back pain remains a leading source of disability worldwide.

METHODS

The review is a synthesis based on the plenary sessions and discussions at the XII International Forum on LBP Research in Primary Care. The presentations included evidence-based reviews of the current state of knowledge in each of the 3 areas (biological, psychological, and social), identification of obstacles to effective implementation and missed opportunities, and identification of the most promising paths for future research.

RESULTS

Although there is good evidence for the role of biological, psychological, and social factors in the etiology and prognosis of back pain, synthesis of the 3 in research and clinical practice has been suboptimal.

CONCLUSION

The utility of the biopsychosocial framework cannot be fully assessed until we truly adopt and apply it in research and clinical practice.

LEVEL OF EVIDENCE

N/A.

Low back pain across the life course

Back pain episodes are traditionally regarded as individual events, but this model is currently being challenged in favour of treating back pain as a long-term or lifelong condition. Back pain can be present throughout life, from childhood to older age, and evidence is mounting that pain experience is maintained over long periods: for example, people with pain continue to have it on and off for years, and people without pain do not suddenly develop long-term pain. A number of factors predict back pain presence in epidemiological studies, and these are often present, and predictive, at different life stages. There are also factors present at particular life stages, such as childhood or adolescence, which predict back pain in adulthood. However, there are little published data on long-term pain patterns or predictors over the life course. Such studies could improve our understanding of the development and fluctuations in back pain, and therefore influence treatment approaches.