Genetic and environmental contributions to back pain in old age: a study of 2,108 danish twins aged 70 and older

Risk factors for non-specific low back pain in older people: a systematic review with meta-analysis

PURPOSE

To conduct a systematic review about risk factors associated with non-specific low back pain (LBP) in older people.

METHODS

The study protocol was prospectively registered with Prospero (CRD42020191619). This systematic review with meta-analysis included cohort studies that investigated risk factors for LBP in older people. The following databases were searched up to 12 December 2020: MEDLINE (Ovid), Embase, CINAHL, SCOPUS and Web of Science. Two independent reviewers appraised methodological quality using the Critical Appraisal Checklist for Cohort Studies instrument.

RESULTS

We identified 3939 potentially relevant publications. After removing duplicates, screening title, and abstracts, we assessed 86 publications in full text. We included the remaining 11 publications for analysis. There is strong evidence that depressive symptoms are a risk of reporting future back pain onset (I² = 52,7%, Odds ratio 1.4, CI 1.28-1.53).

CONCLUSION

Depressive symptoms are a risk factor for LBP in older people. Due to the limitations of the literature, the role of some risk factors remains unclear. An additional high-quality prospective cohort is needed to better elucidate these relationships.

Sex- and age-specific genetic analysis of chronic back pain

ABSTRACT

Sex differences for chronic back pain (cBP) have been reported, with females usually exhibiting greater morbidity, severity, and poorer response to treatment. Genetic factors acting in an age-specific manner have been implicated but never comprehensively explored. We performed sex- and age-stratified genome-wide association study and single nucleotide polymorphism-by-sex interaction analysis for cBP defined as "Back pain for 3+ months" in 202,077 males and 237,754 females of European ancestry from UK Biobank. Two and 7 nonoverlapping genome-wide significant loci were identified for males and females, respectively. A male-specific locus on chromosome 10 near SPOCK2 gene was replicated in 4 independent cohorts. Four loci demonstrated single nucleotide polymorphism-by-sex interaction, although none of them were formally replicated. Single nucleotide polymorphism-explained heritability was higher in females (0.079 vs 0.067, P = 0.006). There was a high, although not complete, genetic correlation between the sexes (r = 0.838 ± 0.041, different from 1 with P = 7.8E-05). Genetic correlation between the sexes for cBP decreased with age (0.858 ± 0.049 in younger people vs 0.544 ± 0.157 in older people; P = 4.3E-05). There was a stronger genetic correlation of cBP with self-reported diagnosis of intervertebral disk degeneration in males than in females (0.889 vs 0.638; P = 3.7E-06). Thus, the genetic component of cBP in the UK Biobank exhibits a mild sex- and age-dependency. This provides an insight into the possible causes of sex- and age-specificity in epidemiology and pathophysiology of cBP and chronic pain at other anatomical sites.

Mutations and structural variations in Catechol-O-methyltransferase gene of patients exhibiting chronic persistent surgical pain

OBJECTIVES

Mutations in the exon 4 of the COMT gene are associated with chronic persistent surgical pain (CPSP). Especially COMT mutated allele G472A (Val158Met) associated with CPSP patients is reported in different ethnic population. The purpose of this study is to evaluate the prevalence of genetic mutations and structural variations in exon 4 of COMT that can be related to the appearance of CPSP in patients under sternotomy.

MATERIALS AND METHODS

One hundred patients with American Society of Anesthesiologists (ASA) physical status grades i, ii and iii, who underwent sternotomy procedures, were selected to assess the development and magnitude of the CPSP evaluated with pain questionaries' at the end of three months after surgery. This was correlated with COMT allele presence. The exon 4 of COMT gene (that contains the G472A allele) was studied. The polymerase chain reaction (PCR) products were sequenced and mutated sequences were deposited in GenBank®. The structural analysis of COMT was performed using ProCheck® and distortions of three-dimensional tertiary structural orientation was evaluated with root-mean-square deviation (RMSD) score.

RESULTS

Genetic analysis carried out through PCR showed 220 bp amplicons. The 25% of patients with CPSP showed a Numeric Rating Scale (NRS) > 4 pain score. The 20% of these patients have known Val158Met mutation, 5% of patients showed novel mutations c.382C>G, c.383G>C, p.(Arg128Ala). The mutations in COMT gene contributed major structural variations in COMT leading to the formation of inactive COMT that correlates with CPSP.

CONCLUSION

The results of the present study showed that both novel and previously reported mutations in COMT gene has strong association with CPSP.

Options to manage postcraniotomy acute pain in neurosurgery: no protocol available

The physical processes of incision, traction and hemostasis used for craniotomy, stimulate nerve fibers and specific nociceptors, resulting in postoperative pain. During the first 24 h after craniotomy, 87% of patients have postoperatory pain. The rate of suffering pain after craniotomy falls 3% for every year of life. The objective of this study is to review the available therapeutic options to help physicians treating this pain, and discuss pain mechanisms, pathophysiology, plasticity, risk factors and psychological factors. This is a narrative review of the literature from 1970 to June 2019. Data were collected by doing a search in PubMed, EMBASE, Cochrane Reviews and a manual search of all relevant literature references. The literature includes some drugs treatment: Opioids, codeine, morphine, and tramadol, anti-inflammatory non-steroids such as cyclooxygenase-2 inhibitors, gabapentin. It discusses: side effects, pharmacodynamics and indications of each drug, anatomy and Inervation of Skull and its Linigs, pathogenesis of pain Post-craniotomy, scalp nerve block, surgical nerve injury, neuronal plasticity, surgical factors and chronic post-surgical pain.

Sequence variation at 8q24.21 and risk of back pain

Back pain (BP) is a common condition of major social importance and poorly understood pathogenesis. Intervertebral lumbar disc degeneration in all its guises is one of the major biological risk factors for BP. Previously, we identified the locus at 8q24.21 associated with chronic BP, which has been found elsewhere associated with sciatica after surgery for lumbar disc herniation. In the current study we used co-localisation methods to identify the gene most likely to harbor the causal variant. We show that the same functional variant at the 8q24.21 locus is responsible for both lumbar disc degeneration and BP, and we also studied the effects of this locus on related phenotypes. Our results link the locus to intervertebral disc and bone mineral density, but not to anthropometric measurements, thus corroborating the epidemiological evidence. Moreover, the same functional variant at the locus is more likely to affect the expression of the nearby FAM49B gene, rather than the GSDMC gene, which was previously proposed as a causative one for BP.

Fear-avoidance beliefs increase perception of pain and disability in Mexicans with chronic low back pain

BACKGROUND

Fear-avoidance beliefs are related to the prognosis of chronicity in low back pain in subacute stages, however in chronic pain, is no clear the influence of these factors; it has been suggested that the study population can determine the magnitude of influence on disability and pain of those suffering from back pain. Currently, information does not exist in the Mexican population.

OBJECTIVE

To analyze the relationship between fear-avoidance beliefs with pain and disability in Mexicans with chronic low back pain; analyze potentials differences between subgroups according to the time of evolution.

METHODS

Cross-sectional study in Mexicans with chronic LBP aged between 18 and 45. Data were collected on general socio demographic characteristics, time of evolution, body mass index, pain, disability and fear-avoidance beliefs.

RESULTS

33 men and 47 women, with an average age of 34.19±7.65 years. Higher scores of fear-avoidance beliefs were obtained in women (47.2±20.99 versus 38.5±9.7; p=0.05) and single participants (p=0.04). A positive correlation was found between disability (r=0.603, p<0.001) and pain (r=0.234, p=0.03) with high scores of fear-avoidance beliefs. Through generalized linear models for disability, total score of the fear avoidance beliefs questionnaire showed a standardized beta coefficient of 0.603, p<0.001 (R² of 0.656); for pain showed a standardized beta coefficient of 0.29, p=0.01 (R² of 0.721).

CONCLUSION

The present study suggests that there is a strong relationship between pain severity, FABQ scores, and functional disability in Mexicans with chronic LBP.

Predicting transition to chronic pain

PURPOSE OF REVIEW

Most individuals who develop pain following an inciting event will return to a healthy state as the injury heals. However, a small percentage continue to suffer, that is, transition to chronic pain. Chronic pain may persist for years and is accompanied by cognitive abnormalities, as well as diminished quality of life. In animals, persistent pain is characterized by peripheral and spinal cord reorganization, and recent evidence in humans also indicates cortical reorganization. Yet, despite more than 30 years of research, there is little agreement on the neural mechanisms that mediate the transition from acute to chronic pain.

RECENT FINDINGS

In a longitudinal brain-imaging study, individuals who developed an intense back pain episode were followed over a 1-year period, during which pain and brain parameters were collected repeatedly. A smaller number of healthy individuals and chronic back pain patients were also studied concomitantly, as positive and negative controls. At the time of entry into the study, strength of synchrony between the medial prefrontal cortex and nucleus accumbens (i.e. functional connectivity) was predictive (>80% accuracy) of individuals who subsequently transition to chronicity 1 year later.

SUMMARY

Properties of the brain's emotional learning circuitry predict the transition to chronic pain. The involvement of this circuitry in pain remains mostly unexplored. Future human and animal model studies are necessary to unravel underlying mechanisms driving pain chronicity, with the potential of advancing novel therapeutics for preventing pain chronification.

Chronic pain after lower abdominal surgery: do catechol-O-methyl transferase/opioid receptor μ-1 polymorphisms contribute?

Background

Preoperative pain, type of operation and anesthesia, severity of acute postoperative pain, and psychosocial factors have been identified as risk factors for chronic postsurgical pain (CPP). Recently, it has been suggested that genetic factors also contribute to CPP. In this study, we aimed to determine whether the catechol-O-methyl transferase (COMT) and opioid receptor μ-1 (OPRM1) common functional polymorphisms rs4680 and rs1799971 were associated with the incidence, intensity, or duration of CPP in patients after lower abdominal surgery.

Methods

One hundred and two patients with American Society of Anesthesiologists (ASA) physical status I/II underwent either abdominal radical prostatectomy (n = 45) or hysterectomy (n = 57). The incidences of CPP in the pelvic and scar areas were evaluated in all patients three months after surgery.

Results

Thirty-five (34.3%) patients experienced CPP after lower abdominal surgery. Within this group, six (17.1%) patients demonstrated symptoms of neuropathic pain. For COMT rs4680, 22 (21.6%) patients had Met158Met, 55 (53.9%) patients had Val158Met, and 25 (24.5%) patients had Val158Val. No association was found between CPP phenotypes (incidence, intensity, and duration) and different rs4680 genotypes. For OPRM1 rs1799971, only CPP patients carrying at least one copy of the G allele had higher pain intensity than A118A carriers (p=0.02). No associations with other phenotypes were found. No combined effect of COMT/OPRM1 polymorphisms on CPP phenotypes was observed.

Conclusions

OPRM1 genotype influences CPP following lower abdominal surgery. COMT didn’t affect CPP, suggesting its potential modality-specific effects on human pain.

Nature or nurture in low back pain? Results of a systematic review of studies based on twin samples

Twin studies are becoming popular to investigate risk factors for low back pain (LBP) because they consider the genetic factor and allow for more precise estimates of risks. We aimed to identify and summarize the results of studies based on twin samples investigating risk factors for LBP. The MEDLINE, CINAHL, LILACS, Web of Science and EMBASE databases were searched. Prospective and cross-sectional observational studies of LBP involving twins were included. The exposure factors could be genetics (heritability) or environmental such as smoking, alcohol consumption, body mass index and medical history. Pooling was attempted using an inverse variance weighting and fixed effects model. Twenty-seven studies were included. Estimates of heritability effects ranged from 21% to 67%. The genetic component was higher for more chronic and disabling LBP than acute and less disabling LBP. Smoking was significantly associated with LBP [pooled odds ratio (OR) = 3.0; 95% confidence interval (CI) 2.8-3.3] with a longitudinal and a cross-sectional study also identifying a dose-response relationship in people with chronic LBP. Obesity was associated with LBP (pooled OR = 1.9; 95% CI 1.6-2.2) with a cross-sectional study identifying a dose-response relationship. No association between alcohol consumption and LBP was identified. Co-morbidities such as asthma, diabetes and osteoarthritis were associated with LBP (pooled OR ranging from 1.6 to 4.2). The contribution of genetics to LBP appears to be dependent on the severity of the condition. Twin studies could be better used to explore possible causation paths between lifestyle factors, co-morbidities and LBP.

Modest associations between self-reported physical workload and neck trouble: a population-based twin control study

OBJECTIVES

To investigate the relationship between self-reported physical workload and neck trouble (NT) in twins. Additionally, to explore whether the relationship between physical workload and NT is influenced by genetic factors.

METHODS

A twin control study was performed within a population-based, cross-sectional questionnaire study using 3,208 monozygotic (MZ) and same-sexed dizygotic (DZ) twins aged 19-70. Twin pairs discordant for self-reported NT during the past year ("Any NT") were included. Self-reported physical workload in four categories was used as exposure ("sitting," "sitting and walking," "light physical," and "heavy physical" work). Paired analyses including conditional logistic regression were made for all participants and for each sex, and MZ and DZ pairs separately.

RESULTS

No marked associations between physical workload and NT were seen. A moderate risk elevation in "heavy physical" work was seen in DZ men (odds ratio 2.3, 95% confidence intervals 1.3-4.0), but not in MZ men or the MZ or DZ women.

CONCLUSIONS

The findings in some degree supported that "heavy physical" work is a determinant of NT, perhaps only in men, but hardly of any greater importance. The different results between DZ and MZ men suggest that genetic factors influence the relationship between physical workload and NT.

Genetic variation in the beta-2 adrenergic receptor is associated with chronic musculoskeletal complaints in adolescents

BACKGROUND

There is significant evidence to suggest that psychological and stress-related factors are important predictors of the onset of chronic widespread pain (CWP) and fibromyalgia (FM). The hypothalamic-pituitary-adrenal axis, together with the efferent sympathetic/adrenomedullary system, influence all body organs (including muscles) during short- and long-term threatening stimuli. The aim of this study was to investigate the relationship between genetic variants in adrenergic candidate genes and chronic musculoskeletal complaints (MSCs) in adolescents.

METHODS

Adolescents from the Western Australian Pregnancy (Raine) Cohort attending the 17-year cohort review completed a questionnaire containing a broad range of psychosocial factors and pain assessment (n = 1004). Blood samples were collected for DNA extraction and genotyping. Genotype data was obtained for 14 single nucleotide polymorphisms (SNPs) in two candidate genes - beta-2 adrenergic receptor (ADRB2) and catecholamine-O-methyltransferase (COMT). Haplotypes were reconstructed for all individuals with genotype data.

RESULTS AND CONCLUSION

Both female gender and poor mental health were associated with (1) an increased risk for chronic, disabling comorbid neck and low back pain (CDCP); and (2) an increase in the number of areas of pain. Of the 14 SNPs evaluated, only SNP rs2053044 (ADRB2, recessive model) displayed an association with CDCP [odds ratio (OR) = 2.49; 95% confidence interval (CI) = 1.25, 4.98; p = 0.01] and pain in three to four pain areas in the last month (OR = 1.86; 95% CI = 1.13, 3.06; p = 0.02). These data suggest that genetic variants in ADRB2 may be involved in chronic MSCs.

Opioid Pharmacogenomics Using a Twin Study Paradigm: Methods and Procedures for Determining Familial Aggregation and Heritability

Opioids are the cornerstone medication for the treatment of moderate to severe pain. However, analgesic opioid requirements and the propensity to suffer from aversive opioid effects, including fatal respiratory depression and addiction, vary widely among patients. The factors underlying the substantial response variance remain largely unknown and need clarification for using opioids more effectively in appropriately selected patients. This ongoing study takes advantage of the twin paradigm to estimate the genetic and environmental contributions to inter-individual differences in opioid responses. Evidence of significant heritability will justify more detailed and extensive genomic studies. The enrollment target is 80 monozygotic and 45 dizygotic twin pairs who undergo a target-controlled infusion of the opioid alfentanil and saline placebo in sequential but randomized order. In a laboratory-type setting, well-defined pharmacodynamic endpoints are measured to quantify pain sensitivity, analgesic opioid effects, and aversive opioid effects including respiratory depression, sedation and reinforcing affective responses. First results obtained in 159 participants provide evidence for the feasibility and utility of this interventional study paradigm to estimate familial aggregation and heritability components of relevant drug effects. Areas highlighted in this report include recruitment strategies, required infrastructure and personnel, selection of relevant outcome measures, drug infusion algorithm minimizing pharmacokinetic variability, and considerations for optimizing data quality and quantity without hampering feasibility. Applying the twin paradigm to complex and potentially harmful studies comprehensively characterizing pharmacological response profiles is without much precedent. Methods and first results including heritability estimates for heat and cold pain sensitivity should be of interest to investigators considering similar studies.

Prevention of chronic pain after surgical nerve injury: amputation and thoracotomy

Although techniques for acute pain management have improved in recent years, a dramatic reduction in the incidence and severity of chronic pain following surgery has not occurred. Amputation and thoracotomy, although technically different, share the commonalities of unavoidable nerve injury and the frequent presence of persistent postsurgical neuropathic pain. The authors review the risk factors for the development of chronic pain following these surgeries and the current evidence that supports analgesic interventions. The inconclusive results from many preemptive analgesic studies may require us to reconceptualize the perioperative treatment period as a time of gradual neurologic remodeling.

High heritability for concurrent low back and neck-shoulder pain: a study of twins

STUDY DESIGN

A cross-sectional study on 21,225 twins based on a Web-based questionnaire was performed in 2005-2006 and administered by the Swedish Twin Registry.

OBJECTIVE

To investigate the importance of genetic factors for the occurrence of "Concurrent low back (LBP) and neck-shoulder pain (NSP)" as well as of "Solely LBP," and "Solely NSP" in an adult population of women and men.

SUMMARY OF BACKGROUND DATA

Many individuals suffering from LBP also have concurrent NSP, and little is known about the factors influencing the occurrence of this spinal comorbidity.

METHODS

Heritability of Concurrent LBP and NSP, solely LBP, and solely NSP was analyzed in 2934 monozygotic twin pairs, 2009 same-sex dizygotic (DZ) twin pairs, and 1960 opposite-sex DZ twin pairs without any known rheumatic disorders using structural equation modeling (SEM).

RESULTS

The SEM showed that 60% of the total variance for concurrent LBP and NSP can be explained by additive genetic effects, which was twice as large as for solely LBP (30%) and more than twice as large as for solely NSP (24%).

CONCLUSION

Genetic factors had a considerably greater importance for the occurrence of concurrent LBP and NSP compared with solely LBP or solely NSP. The influence of genetic factors was similar for solely LBP and solely NSP.

Dor lombar crônica e dor nos membros inferiores em idosas: etiologia em revisão

INTRODUÇÃO: A relação entre dor lombar crônica, dor nos membros inferiores e dependência funcional em idosos evidencia-se pelo comportamento da dor durante a execução de atividades da vida diária. Permanecer em pé, puxar ou empurrar objetos grandes e caminhar podem desencadear dor e causar grande sofrimento para os idosos. OBJETIVO: Identificar as causas descritas na literatura relativas à dor lombar crônica e à dor nos membros inferiores em idosas. MÉTODO: Realizou-se busca, nas bases de dados Medline e Pubmed, de literatura em inglês publicada entre 1992 e 2008. RESULTADOS: Dos 48 artigos encontrados, 33 foram analisados. Entre as causas não mecânicas de dor, foram mencionadas fraturas vertebrais por compressão relacionadas à osteoporose, estenose espinhal lombar, metástases, malignidade, síndrome da cauda equina, bacteremia, infecções geniturinárias, tuberculose, polimialgia reumática, aneurisma aórtico, Doença de Paget e Doença de Parkinson. Entre as causas mecânicas, prevalentes em idosos e relacionadas ao sistema musculoesquelético, foram encontradas indefinições quanto à relação de causa e efeito estabelecida entre osteoartrite e dor. Em mulheres, a relação entre menopausa, uso de estrogênio e ocorrência de osteoporose-fratura-dor parece ainda pouca esclarecida. Associação entre dor lombar e dor nos membros inferiores pode sugerir causas mecânicas ou outras causas, visto que osteoartrite e distúrbios circulatórios, comuns em idosas, nem sempre são fontes de dor. CONCLUSÃO: Pela análise da literatura concluiu-se que, além da etiologia mencionada, outras possibilidades de causas, ainda não completamente identificadas e compreendidas, podem estar na origem da dor lombar e da dor nos membros inferiores de idosas.

Extending conceptual frameworks: life course epidemiology for the study of back pain

BACKGROUND

Epidemiological studies have identified important causal and prognostic factors for back pain, but these frequently only identify a proportion of the variance, and new factors add little to these models. Recently, interest has increased in studying diseases over the life course, stimulated by the 1997 book by Kuh and Ben-Shlomo, a move accompanied by important conceptual and methodological developments. This has resulted in improvements in the understanding of other conditions like cardiovascular and respiratory disease. This paper aims to examine how conceptual frameworks from life course epidemiology could enhance back pain research.

DISCUSSION

Life course concepts can be divided into three categories. Concept 1: patterns over time, risk chains and accumulation. Simple 'chains of risk' have been studied - e.g. depression leading to back pain - but studies involving more risk factors in the chain are infrequent. Also, we have not examined how risk accumulation influences outcome, e.g. whether multiple episodes or duration of depression, throughout the life course, better predicts back pain. One-year back pain trajectories have been described, and show advantages for studying back pain, but there are few descriptions of longer-term patterns with associated transitions and turning points. Concept 2: influences and determinants of pathways. Analyses in back pain studies commonly adjust associations for potential confounders, but specific analysis of factors modifying risk, or related to the resilience or susceptibility to back pain, are rarely studied. Concept 3: timing of risk. Studies of critical or sensitive periods - crucial times of life which influence health later in life - are scarce in back pain research. Such analyses could help identify factors that influence the experience of pain throughout the life course.

SUMMARY

Back pain researchers could usefully develop hypotheses and models of how risks from different stages of life might interact and influence the onset, persistence and prognosis of back pain throughout the life course. Adoption of concepts and methods from life course epidemiology could facilitate this.

Current evidence for a modulation of low back pain by human genetic variants

The manifestation of chronic back pain depends on structural, psychosocial, occupational and genetic influences. Heritability estimates for back pain range from 30% to 45%. Genetic influences are caused by genes affecting intervertebral disc degeneration or the immune response and genes involved in pain perception, signalling and psychological processing. This inter-individual variability which is partly due to genetic differences would require an individualized pain management to prevent the transition from acute to chronic back pain or improve the outcome. The genetic profile may help to define patients at high risk for chronic pain. We summarize genetic factors that (i) impact on intervertebral disc stability, namely Collagen IX, COL9A3, COL11A1, COL11A2, COL1A1, aggrecan (AGAN), cartilage intermediate layer protein, vitamin D receptor, metalloproteinsase-3 (MMP3), MMP9, and thrombospondin-2, (ii) modify inflammation, namely interleukin-1 (IL-1) locus genes and IL-6 and (iii) and pain signalling namely guanine triphosphate (GTP) cyclohydrolase 1, catechol-O-methyltransferase, mu opioid receptor (OPMR1), melanocortin 1 receptor (MC1R), transient receptor potential channel A1 and fatty acid amide hydrolase and analgesic drug metabolism (cytochrome P450 [CYP]2D6, CYP2C9).

Towards a theory of chronic pain

In this review, we integrate recent human and animal studies from the viewpoint of chronic pain. First, we briefly review the impact of chronic pain on society and address current pitfalls of its definition and clinical management. Second, we examine pain mechanisms via nociceptive information transmission cephalad and its impact and interaction with the cortex. Third, we present recent discoveries on the active role of the cortex in chronic pain, with findings indicating that the human cortex continuously reorganizes as it lives in chronic pain. We also introduce data emphasizing that distinct chronic pain conditions impact on the cortex in unique patterns. Fourth, animal studies regarding nociceptive transmission, recent evidence for supraspinal reorganization during pain, the necessity of descending modulation for maintenance of neuropathic behavior, and the impact of cortical manipulations on neuropathic pain is also reviewed. We further expound on the notion that chronic pain can be reformulated within the context of learning and memory, and demonstrate the relevance of the idea in the design of novel pharmacotherapies. Lastly, we integrate the human and animal data into a unified working model outlining the mechanism by which acute pain transitions into a chronic state. It incorporates knowledge of underlying brain structures and their reorganization, and also includes specific variations as a function of pain persistence and injury type, thereby providing mechanistic descriptions of several unique chronic pain conditions within a single model.

Bone health and back pain: what do we know and where should we go?

Bone health is generally not considered in patients who present with chronic back pain. Nonetheless, bone health and back pain share common genetic and environmental correlates suggesting a co-dependence. Evidence exists for a relationship between back pain and impaired bone health. Here we present the evidence, theoretic framework and clinical relevance. Bone health and back pain are important determinants of musculoskeletal health. Back pain experienced in youth is a risk factor for future back pain, while suboptimal bone health during development increases the risk of skeletal fragility in later life. Generally, bone health is not considered in patients with chronic back pain who do not demonstrate other well-recognised bone health risk factors or associated conditions. Nonetheless, evidence suggests that back pain and impaired bone health share common environmental and genetic correlates, indicating that bone health ought to be considered in the context of back pain in otherwise healthy individuals. This review describes the likely mechanisms explaining the relationship between back pain and impaired bone health, evidence concerning the relationship and suggestions for future research. A narrative literature search was conducted using CINAHL, Medline, PubMed and Web of Science electronic databases. A history of back pain is associated with decreased bone mineral density in adults, yet this tends to be site-specific. No studies were identified examining this association in youth, yet the negative effects of childhood skeletal trauma and obesity on bone and spinal health provide indirect evidence for an association. Further research is required to clarify the impact of back pain on bone health at different lifespan stages using prospective cohort designs.

An overview of the features influencing pain after inguinal hernia repair

Pain is a prominent issue in inguinal hernia repair research as its persisting appearance is a severe complication. The interest is also urged by the combination of a high number of repairs with an estimated risk for chronic postoperative pain of 11%. Almost every healthcare provider could encounter this complication. Pain is a complex study subject, mostly defined as an unpleasant sensory and emotional experience associated with actual or potential tissue damage. Various explanatory factors for pain following hernia repair have been reported. Most investigators, however, discuss only a few aspects. In the present review, these factors are collected to provide a more holistic synopsis of pain following hernia repair. It may be a resource for understanding this and other postsurgical pain.

Heritability of low back pain and the role of disc degeneration

Twin studies suggest that both disc degeneration and back pain have a genetic component. We were interested in estimating the heritability of low back pain in men and examining whether genetic influences on back pain are mediated through genetic influences on disc degeneration. Thus, we conducted a classic twin study with multivariate quantitative genetic models to estimate the degree to which genetic (or environmental) effects on back pain were correlated with genetic (or environmental) effects on disc degeneration. Subjects included 147 monozygotic and 153 dizygotic male twin pairs (N=600 subjects) from the population-based Finnish Twin Cohort. All subjects underwent lumbar magnetic resonance imaging and completed an extensive interview, including back pain history and exposure to suspected risk factors. Disc height narrowing was the degenerative finding most associated with pain history, and was used to index disc degeneration in the models. Statistically significant genetic correlations were found for disc height narrowing and different definitions of back pain, such as duration of the worst back pain episode (r(g)=0.46) and hospitalization for back problems (r(g)=0.49), as well as disability in the previous year from back pain (r(g)=0.33). The heritability estimates for these back pain variables ranged from 30% to 46%. There also were statistically significant, but weaker, environmental correlations for disc height narrowing with back symptoms over the prior year. A substantial minority of the genetic influences on pain was due to the same genetic influences affecting disc degeneration. This suggests that disc degeneration is one pathway through which genes influence back pain.

Active lifestyle protects against incident low back pain in seniors: a population-based 2-year prospective study of 1387 Danish twins aged 70-100 years

STUDY DESIGN

Prospective cohort study of twins.

OBJECTIVES

To investigate associations between physical activity, physical function, and incident low back pain (LBP) in an elderly population.

SUMMARY OF BACKGROUND DATA

The relationship between an active lifestyle and LBP in seniors is unknown.

METHODS

Participants in the population-based Longitudinal Study of Aging Danish Twins free from LBP at baseline (no LBP during the past month) were included, and interview data on physical activity, overall physical function, and LBP at baseline and follow-up were obtained. Associations between levels of physical activity and LBP were estimated using logistic regression for the entire cohort, and using a matched case-control design for twin pairs discordant for physical activity. Absolute risk and relative risks for incident LBP in relation to physical activity were calculated for participants with higher or lower than average physical function at baseline. Absolute risk for LBP was also calculated for participants based on whether they remained active or inactive between baseline and follow-up or changed activity level.

RESULTS

A total of 1387 persons aged 70-100 at baseline were included in the analyses, including 86 twin pairs discordant for physical activity at baseline. In the total sample, 83% were engaged in light physical activity, and 42% of men and 35% of women were engaged in strenuous physical activity at least weekly. Being engaged in strenuous physical activity at baseline was strongly protective in relation to both having had any LBP (odds ratio 0.21, 95% confidence interval 0.12-0.37 for intra-pair analysis) and having had LBP lasting more than 30 days altogether during the past year at follow-up (odds ratio 0.08, 95% confidence interval 0.03-0.18 for intra-pair analysis). Statistically significant dose-response associations between increasing frequency of strenuous physical activity and magnitude of this protective effect were found. Participants with poor initial physical function experienced the strongest protective effect of strenuous physical activity. Finally, LBP does not appear to be an important factor affecting whether participants remained engaged in strenuous physical activity at baseline and follow-up or vice versa.

CONCLUSIONS

Strenuous physical activity at least once a week is protective for incident LBP in seniors.

Establishment of a novel intervertebral disc/endplate culture model: analysis of an ex vivo in vitro whole-organ rabbit culture system

STUDY DESIGN

Ex vivo in vitro study evaluating a novel intervertebral disc/endplate culture system.

OBJECTIVES

To establish a whole-organ intervertebral disc culture model for the study of disc degeneration in vitro, including the characterization of basic cell and organ function.

SUMMARY OF BACKGROUND DATA

With current in vivo models for the study of disc and endplate degeneration, it remains difficult to investigate the complex disc metabolism and signaling cascades. In contrast, more controlled but simplified in vitro systems using isolated cells or disc fragments are difficult to culture due to the unconstrained conditions, with often-observed cell death or cell dedifferentiation. Therefore, there is a demand for a controlled culture model with preserved cell function that offers the possibility to investigate disc and endplate pathologies in a structurally intact organ.

METHODS

Naturally constrained intervertebral disc/endplate units from rabbits were cultured in multi-well plates. Cell viability, metabolic activity, matrix composition, and matrix gene expression profile were monitored using the Live/Dead cell viability test (Invitrogen, Basel, Switzerland), tetrazolium salt reduction (WST-8), proteoglycan and deoxyribonucleic acid quantification assays, and quantitative polymerase chain reaction.

RESULTS

Viability and organ integrity were preserved for at least 4 weeks, while proteoglycan and deoxyribonucleic acid content decreased slightly, and matrix genes exhibited a degenerative profile with up-regulation of type I collagen and suppression of collagen type II and aggrecan genes. Additionally, cell metabolic activity was reduced to one third of the initial value.

CONCLUSIONS

Naturally constrained intervertebral rabbit discs could be cultured for several weeks without losing cell viability. Structural integrity and matrix composition were retained. However, the organ responded to the artificial environment with a degenerative gene expression pattern and decreased metabolic rate. Therefore, the described system serves as a promising in vitro model to study disc degeneration in a whole organ.

Monitoring the effects and managing the side effects of anticoagulation during pregnancy

LMWHs are the major anticoagulant/antithrombotic treatment given to pregnant women to prevent and treat venous thromboembolism despite the absence of specific clinical trials. An emerging indication, the prevention of adverse pregnancy outcomes, is under investigation. During pregnancy, LMWHs seem to be safe and efficient. Some uncertainties remain about the management of rare potential side effects, particularly in the event of heparin intolerance and with cross-reactivity to danaparoid sodium.

Persistent postsurgical pain: risk factors and prevention

Acute postoperative pain is followed by persistent pain in 10-50% of individuals after common operations, such as groin hernia repair, breast and thoracic surgery, leg amputation, and coronary artery bypass surgery. Since chronic pain can be severe in about 2-10% of these patients, persistent postsurgical pain represents a major, largely unrecognised clinical problem. Iatrogenic neuropathic pain is probably the most important cause of long-term postsurgical pain. Consequently, surgical techniques that avoid nerve damage should be applied whenever possible. Also, the effect of aggressive, early therapy for postoperative pain should be investigated, since the intensity of acute postoperative pain correlates with the risk of developing a persistent pain state. Finally, the role of genetic factors should be studied, since only a proportion of patients with intraoperative nerve damage develop chronic pain. Based on information about the molecular mechanisms that affect changes to the peripheral and central nervous system in neuropathic pain, several opportunities exist for multimodal pharmacological intervention. Here, we outline strategies for identification of patients at risk and for prevention and possible treatment of this important entity of chronic pain.

Chronic back pain among the elderly: prevalence, associations, and predictors

STUDY DESIGN

A longitudinal age homogeneous cohort study.

OBJECTIVE

To describe the prevalence, nature, and predictors of chronic back pain (CBP) in older people.

SUMMARY OF BACKGROUND DATA

CBP is a growing source of morbidity among the elderly. Few longitudinal studies exist, and its time course and predictors are largely undefined.

METHODS

The Jerusalem Longitudinal Study assessed 277 subjects aged 70 years at baseline and 77 years at follow-up. Data collection included back pain symptoms, psychosocial, functional, and physical domains.

RESULTS

The prevalence of CBP increased from 44% to 58% at ages 70 and 77 years, respectively, while frequency and severity decreased. CBP was associated with female gender, economic difficulties, loneliness, fatigue, poor self-rated health, dependence in activities of daily living, joint pain, and obesity. Depression was associated at age 70 years, and unemployment, not leaving the house for leisure, poor sleep satisfaction, hypertension, and osteoporosis were at age 77 years. Predictors of CBP at age 77 years were female gender, loneliness, joint pain, hypertension, and preexisting CBP. Unemployment and not leaving the house for leisure showed a trend toward significance.

CONCLUSION

CBP is increasingly common in the elderly. Psychosocial factors, female gender, hypertension, and existing joint pain identify individuals most at risk.

Does Gynecologic Surgery Contribute to Low Back Problems in Later Life? An Analysis of the Women’s Health and Aging Study

OBJECTIVE

To examine whether women with potential injuries to the abdominal and pelvic musculature from past gynecologic surgery are at higher risk for low back pain (LBP).

DESIGN

Cross-sectional population-based study.

SETTING

Eastern region of the city and county of Baltimore, MD.

PARTICIPANTS

Disabled women (N=1002) aged 65 and older, 448 of whom reported gynecologic surgery who were participants in the Women's Health and Aging Study.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

LBP presence in the last year, LBP severity for the last month, and adjudicated lumbar diagnoses (disk disease, stenosis) were examined in relation to reports of surgical menopause or ovarian surgery adjusted for LBP risk factors.

RESULTS

Women with surgical menopause experienced more moderate LBP (adjusted odds ratio [AOR]=1.59; 95% confidence interval [CI], 1.1-2.3) than women without surgical menopause. Women with ovarian surgery also experienced more moderate LBP than women without ovarian surgery, but this association was not statistically significant (AOR=1.39; 95% CI, 0.96-2.09). Gynecologic surgery was not associated with an increased likelihood of lumbar disk disease or stenosis.

CONCLUSIONS

Surgical menopause may increase the risk of moderate LBP. Further research is needed to determine how gynecologic surgery might influence low back pathology. Abdominal and pelvic muscle rehabilitation after gynecologic surgery may provide protection from LBP later in life.

Epidemiology of back disorders: prevalence, risk factors, and prognosis

PURPOSE OF REVIEW

This article reviews some of the advances that have taken place in understanding back disorders, with a particular emphasis on low back pain, as this area has been most represented in the literature in the preceding year (September 2003 to September 2004).

RECENT FINDINGS

Epidemiological studies continue to provide insights into the prevalence of back pain and have identified many individual, psychosocial, and occupational risk factors for its onset. Psychological factors have an important role in the transition from acute to chronic pain and related disability. Recent advances show that there is a significant genetic effect on severe low back pain in the community. Data emerging from candidate gene studies show an association between lumbar disc disease and mutations of genes encoding the alpha-2 and alpha-3 subunits of collagen IX.

SUMMARY

Back pain is among the most common conditions for which patients seek medical care. Interventions based on behavioral and cognitive principles and exercise programs are effective in improving disability in chronic back pain. Although progress has been made in understanding the role of genetic mutations in disorders such as lumbar disc disease, further investigation of the interaction between genetic and environmental factors such as physical stress is needed.

Small effect of genetic factors on neck pain in old age: a study of 2,108 Danish twins 70 years of age and older

STUDY DESIGN

Classic twin study.

OBJECTIVES

To determine the heritability of neck pain in persons 70 years of age and older.

SUMMARY OF BACKGROUND DATA

Previous studies have shown a moderate effect of genetic factors on back pain in the elderly. Genetic influence on neck pain in old age is unknown.

METHODS

Data on the 1-month prevalence of neck pain from twin pairs participating in the population based Longitudinal Study of Aging Danish Twins formed the basis of this analysis. To assess twin similarity, probandwise concordance rates, odds ratios, and tetrachoric correlations were calculated and compared for monozygotic and dizygotic twins. Further, heritability estimates were calculated using bivariate probit estimation.

RESULTS

A total of 2,108 twin individuals, including 1,054 complete twin pairs, answered the question related to neck pain at intake into the Longitudinal Study of Aging Danish Twins study. Low and nonsignificant probandwise concordance rates, odds ratios, and tetrachoric correlations were found for both men and women in monozygotic and dizygotic twin pairs, indicating small or negligible genetic effects. Heritability estimates adjusted for age and significant environmental risk factors (rheumatoid arthritis, osteoarthritis, disc prolapse, and coronary heart disease) showed no significant additive genetic, dominant genetic, or common environmental effects.

CONCLUSION

Genetic factors do not play an important role in the liability to neck pain in persons 70 years of age or older.