What mediates the inverse association between education and occupational disability from back pain?--A prospective cohort study from the Nord-Trøndelag health study in Norway

Overweight and obesity as risk factors for chronic low back pain: a new follow-up in the HUNT Study

BACKGROUND

Numerous studies have examined associations between overweight and obesity and risk of low back pain (LBP), but the exact magnitude of these associations is not yet clear. The purpose of this work was to assess such sex-specific associations in a community-based setting in Norway, taking into account potential relationships with other risk factors.

METHODS

A cohort study was conducted combining data from two waves of the Trøndelag Health Study, HUNT3 (2006-2008) and HUNT4 (2017-2019). Separate analyses were performed of risk of chronic LBP in HUNT4 among 14,775 individuals without chronic LBP in HUNT3, and of recurrence or persistence in HUNT4 among 5034 individuals with chronic LBP in HUNT3. Relative risks were estimated in generalised linear models for overweight and obesity compared to normal weight. Body size classification was based on values of BMI computed from measurements of height and weight. Chronic LBP was defined as LBP persisting at least 3 months during last year.

RESULTS

After adjustment for age, smoking, physical activity in leisure time and work activity, analysis of risk among women produced relative risks 1.11 (95% CI 1.00-1.23) for overweight, 1.36 (95% CI 1.20-1.54) for obesity class I and 1.68 (95% CI 1.42-2.00) for obesity classes II-III. Relative risks among men were 1.10 (95% CI 0.94-1.28) for overweight, 1.36 (95% CI 1.13-1.63) for obesity class I and 1.02 (95% CI 0.70-1.50) for obesity classes II-III, the last estimate being based on relatively few individuals. Analyses of recurrence or persistence indicated similar relationships but with smaller magnitude of relative risks and no drop in risk among obesity classes II-III in men. The change in BMI from HUNT3 to HUNT4 hardly differed between individuals with and without chronic LBP in HUNT3.

CONCLUSIONS

Risk of chronic LBP increases with higher values of BMI in both sexes, although it is uncertain whether this applies to very obese men. Very obese women carry a particularly large risk. Probabilities of recurrence or persistence of chronic LBP among those already afflicted also increase with higher values of BMI. Adjustment for other factors does not influence relationships with overweight and obesity to any major extent.

The role of lifestyle factors in the association between education and self-reported fibromyalgia: a mediation analysis

BACKGROUND

Socioeconomic status as measured by education, income, or occupation, has been associated with fibromyalgia but the underlying mechanism and the role of lifestyle factors are unclear. Thus, we examine the role of modifiable lifestyle factors (body mass index, physical activity, alcohol consumption and smoking) in the association between education and self-reported fibromyalgia.

METHODS

We used data from 74,157 participants in the population-based prospective Norwegian Women and Cancer (NOWAC) study. Socioeconomic position, operationalized as years of educational attainment, and lifestyle factors were assessed via self-reported questionnaires. Multiple mediation analysis was used to decompose total effects into direct and indirect effects. Estimates were reported as hazard ratios (HRs) with 95% confidence intervals (CIs).

RESULTS

The cumulative incidence of fibromyalgia was 3.2% after a median follow up time of 13 years. Fibromyalgia was inversely associated with years of educational attainment for ≤ 9 years (HR = 2.56; 95% CI 2.32-2.91) and for 10-12 years (HR = 1.84; 95% CI 1.72-2.02), compared with ≥ 13 years of education. Overall, all lifestyle factors together jointly mediated 17.3% (95% CI 14.3-21.6) and 14.1% (95% CI 11.3-18.9) of the total effect for ≤ 9 years and 10-12 years of education, respectively. Smoking and alcohol consumption contributed the most to the proportion mediated, for ≤ 9 years (5.0% and 7.0%) and 10-12 years (5.6% and 4.5%) of education.

CONCLUSION

The association between education and self-reported fibromyalgia was partly explained through lifestyle factors, mainly smoking and alcohol consumption.

Socioeconomic risk factors for long-term opioid use: A national registry-linkage study

BACKGROUND

Opioid use has increased substantially as a treatment for chronic pain, although harms from long-term opioid therapy outweigh the benefits. More knowledge about factors associated with long-term opioid use is needed. We aimed to investigate the association between socioeconomic status and long-term opioid use in the period 2010-2019.

METHODS

This was a nested case-control study in which the cases were all persons ≥18 years with long-term opioid use, that is use of opioids for more than 3 months (N = 215,642). Cases were matched on gender, age and index year (first long-term use period) with four controls who filled at least one opioid prescription, but never developed long-term opioid use in the study period (N = 862,568). We performed a logistic regression analysis adjusted for relevant confounders, stratified on age groups (18-67 years and 68 years and above).

RESULTS

In the younger age group, long-term opioid use was associated with low education (adjusted odds ratio, aOR = 1.54; 95% confidence interval, CI [1.51-1.57]), low income (1.33 [1.31-1.36]), being unemployed (1.40 [1.38-1.42]) and receiving disability pension (1.36 [1.33-1.38]). Weaker associations were found for living in a single-person household or in a dense geographical area. Similar associations were found for the older age group.

CONCLUSION

We found that low socioeconomic status was associated with long-term opioid use both among people in working age and older people. These results indicate a need for social and financial support for non-pharmacological treatment of chronic pain among people with lower socioeconomic status.

SIGNIFICANCE

This study shows that people with low socioeconomic status are at higher risk of developing long-term opioid use. In the clinical setting, physicians should consider socioeconomic status when prescribing opioids for chronic pain. Non-pharmacological treatment options funded by public health services should be prioritized to those with low socioeconomic status as long-term opioid use in chronic pain patients is not recommended.

Menopausal hormone therapy, oral contraceptives and risk of chronic low back pain: the HUNT Study

BACKGROUND

There are indications that use of menopausal hormone therapy (MHT) and oral contraceptives (OC) increases the risk of low back pain (LBP), with higher oestrogen levels involved in the underlying mechanisms. The purpose of the present study was to investigate associations between use of systemic MHT or OC and risk of chronic LBP in a large population-based data set.

METHODS

Data were obtained from two surveys in the Trøndelag Health Study in Norway, HUNT2 (1995-1997) and HUNT3 (2006-2008). A cross-sectional study of association between use of systemic MHT and prevalence of chronic LBP comprised 12,974 women aged 40-69 years in HUNT2, with 4007 women reporting chronic LBP. A cohort study involving MHT comprised 6007 women without chronic LBP at baseline in HUNT2, and after 11 years 1245 women reported chronic LBP at follow-up in HUNT3. The cross-sectional study of association with use of OC included 23,593 women aged 20-69 years in HUNT2, with 6085 women reporting chronic LBP. The corresponding cohort study included 10,586 women without chronic LBP at baseline in HUNT2, of whom 2084 women reported chronic LBP in HUNT3. Risk of chronic LBP was examined in both study designs in generalised linear models with adjustment for potential confounders.

RESULTS

In the cohort study, current users of systemic MHT at baseline showed a greater risk of chronic LBP (relative risk (RR) 1.30; 95% CI: 1.14-1.49; compared with never users). The risk increased according to duration of MHT use (P for linear trend = 0.003). Known users of systemic MHT based exclusively on oestrogen experienced the highest risk (RR 1.49; 95% CI: 1.16-1.91), but an increased risk was also seen among known users of oestrogen-progestin combination MHT (RR 1.35; 95% CI: 1.16-1.57). A slight increase in risk of chronic LBP was found in the cohort study among former users of OC (RR 1.17; 95% CI: 1.06-1.30; compared with never users).

CONCLUSIONS

Long-lasting use of systemic MHT, in particular therapy based on oestrogen only, is associated with greater risk of chronic LBP. Having been a user of OC most likely entails a minor increase in risk.

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.

Significant other interactions in people with chronic low back pain: Subgrouping and multidimensional profiles

Background: Back pain is complex. Social support and significant other interactions influence the pain experience. Purpose: To statistically derive subgroups of people with chronic low back pain based upon their interactions with significant others, and profile subgroups across multidimensional variables. Research Design: Longitudinal cohort study. Study Sample: People with chronic axial low back pain ( n = 262). Data Collection and Analysis: Latent class analysis of significant other interaction data was used to derive subgroups of people with chronic low back pain. Subgroups were profiled across baseline multidimensional variables and one-year follow-up pain intensity, disability and bothersomeness. Results: Three clusters were identified: Cluster 1 (7.6%) characterised by the lowest distracting, punishing and solicitous interactions. Cluster 2 (16.0%) characterised by the highest distracting and solicitous responses and social support. Cluster 3 (76.3%) characterised by the highest punishing and lowest social support. Cluster 1 reported less disability than Clusters 2 and 3. Mindfulness was significantly different across all subgroups with Cluster 1 being most mindful and Cluster 3 least mindful. Depression, anxiety and stress were significantly higher in Cluster 3 than Cluster 1. Pain catastrophising was higher for Cluster 2 than Clusters 1 and 3. Cluster 2 had lower pressure pain threshold than Clusters 1 and 3. Conclusions: These results support the association between significant other interactions and the experience of back pain. Considering significant other interactions in clinical practice may be important for managing some people’s presentation.

The prevalence and risk factors of chronic low back pain among adults in KwaZulu-Natal, South Africa: an observational cross-sectional hospital-based study

Background

Globally, chronic low back pain (CLBP) is the leading cause of disability associated with economic costs. However, it has received little attention in low-and-middle-income countries. This study estimated the prevalence and risk factors of CLBP among adults presenting at selected hospitals in KwaZulu-Natal.

Methodology

This cross-sectional study was conducted among adults aged ≥18 years who attended the selected hospitals in KwaZulu-Natal during the study period. A self-administered questionnaire was used to collect data on socio-demographic, work-related factors, and information about CLBP. The SPSS version 24.0 (IBM SPSS Inc) was used for data analysis. Descriptive statistics were used for demographic characteristics of participants. CLBP risk factors were assessed using multivariate logistic regression analysis. A p-value of ≤0.05 was deemed statistically significant.

Results

A total of 678 adults participated in this study. The overall prevalence of CLBP was 18.1% (95% CI: 15.3 – 21.3) with females having a higher prevalence than males, 19.8% (95% CI: 16.0 – 24.1) and 15.85% (95% CI: 11.8 – 20.6), respectively. Using multivariate regression analysis, the following risk factors were identified: overweight (aOR: 3.7, 95% CI: 1.1 – 12.3, p = 0.032), no formal education (aOR: 6.1, 95% CI: 2.1 – 18.1, p = 0.001), lack of regular physical exercises (aOR: 2.2, 95% CI: 1.0 – 4.8, p = 0.044), smoking 1 to 10 (aOR: 4.5, 95% CI: 2.0 – 10.2, p < 0.001) and more than 11 cigarettes per day (aOR: 25.3, 95% CI: 10.4 – 61.2, p < 0.001), occasional and frequent consumption of alcohol, aOR: 2.5, 95% CI: 1.1 – 5.9, p < 0.001 and aOR: 11.3, 95% CI: 4.9 – 25.8, p < 0.001, respectively, a sedentary lifestyle (aOR: 31.8, 95% CI: 11.2 – 90.2, p < 0.001), manual work (aOR: 26.2, 95% CI: 10.1 – 68.4, p < 0.001) and a stooped sitting posture (aOR: 6.0, 95% CI: 2.0 – 17.6, p = 0.001).

Conclusion

This study concluded that the prevalence of CLBP in KwaZulu-Natal is higher than in other regions, and that it is predicted by a lack of formal education, overweight, lack of regular physical exercises, smoking, alcohol consumption, sedentary lifestyle, manual work, and a stooped posture.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04790-9.

A Practice Based Chronic Pain Management Registry (CPMR): Structure and Content of Proposed Patient and Patient/Provider Platforms

Previous commentaries in the Formulary Evaluation section of INNOVATIONS in Pharmacy have pointed to the difficulties of establishing the credibility of trial-based and modeled claims for therapy interventions. Claims for interventions in the management of chronic pain are no exception. To meet this challenge, the Chronic Pain Management Registry (CPMR) has been designed to provide an evidence base for physician practices and health care decision makers to evaluate the impact of pain management interventions. The purpose of this commentary is to detail the development, structure and content of the CPMR in two versions: (i) a patient response version and (ii) a combined patient/provider response version. The CPMR has a potentially critical role to play in providing a framework for the effective auditing of practice compliance in the prescribing and monitoring of opioids in the management of chronic pain. The CPMR tracks, with on-line input from the patient and the treating physician, the process and outcomes of therapy interventions. These reports cover the overall pain experience of patients as well as pain intensity and functional status by eleven specific pain locations, covering both pharmacological and non-pharmacological interventions. Prior to each practice visit patients complete reports which are entered to the CPMR with a summary transmitted to the physician practice. Over time, these reports track the cumulative response to therapy as well as the perception of the patients as to whether or not the therapy has led to any substantive improvement in activity limitations, symptoms and quality of life. A particular focus of the CPMR is on monitoring and evaluating the experience with, and impact of opioid medications, to include the effectiveness of opioid formulations on reducing pain intensity and improving functional status, including an intensive assessment of the potential for and experience of opioid substance abuse for individual patients. The CPMR can also support monthly reports to the practice to summarize patient throughput, the response to care by target pain patients and profiles of opioid use and abuse. The CPMR can be customized to meet the needs of individual practices.

Physical activity level at work and risk of chronic low back pain: A follow-up in the Nord-Trøndelag Health Study

Background

Physical activity in leisure time seems to reduce the risk of low back pain, but it is not known whether occupational activity, as recorded in a representative working population, produces a higher or lower risk.

Objective

To study associations between physical activity level at work and risk of chronic low back pain.

Methods

Associations were examined in a Norwegian prospective study using data from the HUNT2 and HUNT3 surveys carried out in the whole county of Nord-Trøndelag. Participants were 7580 women and 7335 men who supplied information about physical activity level at work. Levels considered were sedentary work, work involving walking but no heavy lifting, work involving walking and heavy lifting, and particularly strenuous physical work. Nobody in the cohort was affected by chronic low back pain at baseline. After 11 years, participants reported whether they suffered from chronic low back pain. Generalized linear modelling with adjustment for potential confounders was applied to assess associations with risk factors.

Results

In age-adjusted analyses both women and men showed statistically significant associations between physical activity at work and risk of chronic low back pain, suggesting positive relationships. For particularly strenuous physical work the relative risk of chronic low back pain was 1.30 (95% CI: 1.00–1.71) in women and 1.36 (95% CI 1.17–1.59) in men, compared to sedentary work. Women still showed a general association with activity level after adjustment for education, leisure time physical activity, BMI, smoking and occupational category. In men, the higher risk was only maintained for particularly strenuous work.

Conclusion

In this cohort, women had a higher risk of chronic low back pain with work involving walking and heavy lifting or particularly strenuous work, compared to sedentary work. Men participating in particularly strenuous work also experienced a higher risk of chronic low back pain.

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.

The contribution from psychological, social, and organizational work factors to risk of disability retirement: a systematic review with meta-analyses

BACKGROUND

Previous studies indicate that psychological, social, and organizational factors at work contribute to health, motivation, absence from work, and functional ability. The objective of the study was to assess the current state of knowledge of the contribution of psychological, social, and organizational factors to disability retirement by a systematic review and meta-analyses.

METHODS

Data sources: A systematic literature search for studies of retirement due to disability in Medline, Embase, and PsychINFO was performed. Reference lists of relevant articles were hand-searched for additional studies.

DATA EXTRACTION

Internal validity was assessed independently by two referees with a detailed checklist for sources of bias. Conclusions were drawn based on studies with acceptable quality.

DATA SYNTHESIS

We calculated combined effect estimates by means of averaged associations (Risk ratios) across samples, weighting observed associations by the study's sample size. Thirty-nine studies of accepted quality were found, 37 of which from the Nordic countries.

RESULTS

There was moderate evidence for the role of low control (supported by weighted average RR = 1.40; 95% CI = 1.21-1.61) and moderate evidence for the combination of high demands and low control (although weighted average was RR = 1.45; 95% CI = 0.96-2.19) as predictors of disability retirement. There were no major systematic differences in findings between the highest rated and the lowest rated studies that passed the criterion for adequate quality. There was limited evidence for downsizing, organizational change, lack of employee development and supplementary training, repetitive work tasks, effort-reward imbalance to increase risk of disability pension. Very limited evidence was found for job demands, evening or night work, and low social support from ones superior.

CONCLUSIONS

Psychological and organizational factors at work contribute to disability retirement with the most robust evidence for the role of work control. We recommend the measurement of specific exposure factors in future studies.

Musculoskeletal pain at various anatomical sites and socioeconomic position: Results of a national survey

BACKGROUND

Prevalence of musculoskeletal pain according to sites of pain and associated factors in the community has not been thoroughly documented. The association between pain and socioeconomic position has been studied by several authors, but without details in most studies regarding sites of pain, whereas the relations with social position could differ according to the site of pain. The objective of this study was to explore these differences in the community in France.

METHODS

The national Health and Occupational History survey was conducted in France in 2006 in subjects aged 20-74 years. Self-assessment of pain at various sites in the previous year was recorded. Five sites were considered here: back, neck, shoulder, upper limb, and lower limb. After a description of prevalence according to gender and age, the associations with socioeconomic position at the beginning of the subjects' working life, in seven categories, were studied with logistic models adjusted for age. The analyses were limited to those aged 30-74 years and were conducted separately for men and women.

RESULTS

Of the 5520 males and 6643 females studied, prevalence was the highest for back pain (35% for males, 37% for females). Pain was globally more frequent for women. For all sites of pain an increase with age was significant for women. This was not observed in men for back pain (highest prevalence in the 40- to 49-year-old age group) or neck pain. Overall, prevalence of pain was the lowest for professionals (reference category in the analyses). For males, the first occupation as a farmer or blue-collar worker was associated with an increased prevalence for most sites of pain, with odds ratios close to 2. For females, prevalence was increased for more socioeconomic categories, as compared to professionals. Among the five sites, neck pain was an exception: for both men and women, no association was observed between neck pain and socioeconomic position.

CONCLUSION

Although exploratory, these results are consistent with the available knowledge on occupational and personal risk factors for pain, which differ according to the site of pain. Other studies are needed to better understand the causal mechanisms underlying the associations observed.

The prevalence of low back pain and its associated factors in Thai rubber farmers

Objectives:

Low back pain (LBP) is one of the most prevalent musculoskeletal disorders in the general population, especially among manual laborers. Moreover, it often brings about lost wages and additional medical expenses. However, the potential risk factors for LBP are unknown. This study aimed to estimate the prevalence of LBP and to determine the individual, occupational, and psychosocial factors associated with LBP among rubber farmers.

Methods:

A cross-sectional survey was conducted among 450 Thai rubber farmers using cluster random sampling. Data were collected using face-to-face interviews and objective examination and were analyzed using multivariate logistic regression.

Results:

Of the 433 rubber farmers, the point and 12-month prevalence of LBP in rubber farmers was 33% and 55.7%, respectively. BMI, primary school education, exposure to pesticides, and tapping below knee level were statistically associated with LBP after controlling for other variables.

Conclusions:

Low back pain is common among rubber farmers. Only four factors were identified as being associated with the high prevalence of LBP. However, these factors might be altered if more variables are taken into account. Further research investigating the causal relation between these factors and LBP should be conducted.

Is there a U-shaped relationship between physical activity in leisure time and risk of chronic low back pain? A follow-up in the HUNT Study

Background

Physical activity in leisure time is often considered to have favourable effects on the risk of low back pain (LBP), but demonstrating a definite association in epidemiological studies has proven difficult. The purpose of the present study was to explore associations between physical activity and risk of chronic LBP in an adult population and to investigate whether relationships are limited to certain age groups or to females or males. A particular objective was to determine whether support could be found for a U-shaped relationship, with both low and high activity levels carrying greater risk.

Methods

The relationship between physical activity and risk of chronic LBP was examined in a Norwegian prospective study using data from the community-based HUNT2 and HUNT3 surveys. Participants were 9616 women and 8452 men without LBP at baseline, who reported after 11 years whether they suffered from LBP. Associations between baseline physical activity in leisure time and risk of chronic LBP at end of follow-up were evaluated by generalized linear modelling with adjustment for potential confounders.

Results

Significant associations between leisure time physical activity and risk were observed in both sexes after age adjustment, mainly suggesting inverse relationships. Women participating in hard physical activity 1–2 h per week had a relative risk (RR) of chronic LBP of 0.81 (95 % CI 0.71–0.93) compared to those with only light physical activity less than 1 h per week. The corresponding RR in men was 0.71 (95 % CI 0.60–0.85). After adjustment for education, employment, occupational activity, body mass index (BMI) and smoking, significant relationships could only be demonstrated in those aged 50 years or more at baseline. The associations differed between female educational groups, with more U-shaped relationships being observed among women with basic education only.

Conclusion

No strong support was found overall for U-shaped relationships. However, no further general decrease in risk was seen among those with 3 h or more of hard physical activity per week. The contrasts observed between female educational groups may reflect different preferences regarding specific strenuous activities. Men aged 50 years or more seem in particular to benefit from hard physical activities.

Investigating the temporal relationship between individual-level social capital and health in fragile families

Background

The potential for social capital to influence health outcomes has received significant attention, yet few studies have assessed the temporal ordering between the two. Even less attention has been paid to more vulnerable populations, such as low-income women with children. Our objective was to explore how different dimensions of social capital impact future health status among this population.

Methods

This study uses data from the Fragile Families and Child Well-Being (FFCWB) Study, which has followed a cohort of children and their families born in large U.S. cities between 1998 and 2000 to mostly minority, unmarried parents who tend to be at greater risk for falling into poverty. Four separate measures of social capital were constructed, which include measures of social support and trust, social participation, perceptions of neighborhood social cohesion, and perceptions of neighborhood social control. The temporal effect of social capital on self-reported health (SRH) is investigated using logistic regression and we hypothesize that higher levels of social capital are associated with higher levels of self-rated health.

Results

After controlling for socioeconomic and demographic factors related to social capital and self-rated health, social support and trust, perceptions of neighborhood social cohesion and control at an earlier point in time were positively associated with higher levels of health four-years later. Social participation was not related to increased health. The empirical results appear robust.

Conclusion

Higher levels of social capital are predictive of improved health over a four-year time frame. These results suggest that policy initiatives supporting increasing the social capital available and accessible by low-income, urban, minority women are viable for improving health. Such policies may have the potential to reduce socioeconomic health disparities.

Economic difficulties and subsequent disability retirement

BACKGROUND

This study examined whether economic difficulties are associated with subsequent disability retirement while controlling for covariates.

METHODS

Survey data among middle-aged employees of the City of Helsinki in 2000-2002 were linked with the Finnish Centre for Pensions register data on all-cause disability retirement among women (n=4816) and men (n=1354) until the end of 2010. Additionally, disability retirement due to musculoskeletal diseases and mental disorders (ICD-10) was examined among women. Frequency in difficulties paying pills and buying food and clothes, and covariates (occupational class, income, housing tenure, and work- and health-related covariates) were self-reported at baseline. Hazard ratios (HR) and their 95% confidence intervals (95% CI) were calculated from Cox regression analysis.

RESULTS

Frequent economic difficulties were associated with all-cause disability retirement after adjusting for age among both women (HR=2.11; 95% CI 1.63-2.73) and men (HR=2.69; 95% CI 1.65-4.41). Adjustment for covariates somewhat attenuated the associations, but they remained. Economic difficulties were also associated with disability retirement due to both mental disorders (HR=3.29; 95% CI 1.98-5.46) and musculoskeletal diseases (HR=1.85; 95% CI 1.24-2.75) among women. Adjustments made a minor contribution to the risk of disability retirement due to mental disorders, whereas the risk of disability retirement due to musculoskeletal diseases reduced after considering socioeconomic circumstances. Conclusions: economic difficulties are independently associated with disability retirement. Thus, they should be considered in attempts to tackle early exit from the labour market due to disability.

Consequences of musculoskeletal disorders on occupational events: a life-long perspective from a national survey

INTRODUCTION

Musculoskeletal disorders (MSDs) are among the most frequent causes of disability, with potentially important consequences. Our objective was to investigate from a lifelong perspective the factors associated with these consequences, including permanent withdrawal from the workforce, focusing especially on factors at the start of working life.

METHODS

The data come from the SIP national survey (Santé et Histoire Professionnelle, health and occupational history). Three groups of subjects were compared with multinomial logistic models: group 1 (G1), who had MSDs that caused an important event in their working life; group 2, who had MSDs without any such consequence; and group 3 (G3), who had no MSD.

RESULTS

In multivariate models, MSDs with consequences on occupational events were strongly associated with a low educational level for both sexes, and with some working conditions. In the comparison G1/G3, the odds-ratio (OR) for "no diploma" compared to "university level" was 4.41 and the confidence interval (95 % CI) 2.31-8.40 for men. For women the OR was 2.02 (95 % CI 1.32, 3.10). Group 2's educational level was between G1 and G3, closer to G3. For men, another risk factor was a first job in construction or farming (OR = 2.95 for construction, 2.23 for farming, comparison G1/G3). Comparisons focusing on "permanent withdrawal from the workforce" yielded similar results.

CONCLUSIONS

Associations between occupational history and health are complex; the results strongly suggest that factors at the beginning of working life, including level of education, have important delayed consequences, especially for workers with health disorders such as MDSs. In order to reduce the frequency of negative consequences, a better knowledge on causal mechanisms would be needed.

Work characteristics, socioeconomic position and health: a systematic review of mediation and moderation effects in prospective studies

Social inequalities in health persist in modern societies. The contribution of adverse work and employment conditions towards their explanation is analysed by two approaches, mediation and moderation. Yet the relative significance of each approach remains unclear in respective research. We set out to study this question by conducting a systematic literature review. We included all original papers based on prospective observational studies of employed cohorts that were published between January 1980 and October 2012 meeting our search criteria, by using major databases and by observing established quality criteria. 26 reports were included after quality assessment. 17 studies examined the mediation hypothesis and nine studies tested the moderation hypothesis. Moderate support was found for the mediation hypothesis where OR or HR of health according to socioeconomic position (SEP) were reduced in a majority of analyses after introducing work characteristics in multivariate models. Evidence in favour of the moderation hypothesis was found in some studies, demonstrating stronger effects of adverse work on health among people with low SEP. Despite some support in favour of the two hypotheses future research should aim at reducing the heterogeneity in defining and measuring core variables and at applying advanced statistical analyses. Policy recommendations would benefit from a higher degree of consistency of respective research evidence.

Workers who stay at work despite chronic nonspecific musculoskeletal pain: do they differ from workers with sick leave?

PURPOSE

Most workers with chronic nonspecific musculoskeletal pain (CMP) do not take sick leave, nor consult a health care professional or search vocational rehabilitation. Yet, the knowledge of many researchers, clinicians and policy makers is largely based on people with CMP who discontinue work. The aim of this study was to explore characteristics of workers who stay at work despite CMP, and to compare these with sick-listed workers with CMP following vocational rehabilitation.

METHODS

The clinical characteristics of workers who stay at work despite CMP (n = 119) and sick-listed workers who follow vocational rehabilitation (n = 122) were described and the differences between these groups were assessed. Logistic regression analysis was used to assess differences between the groups and to determine which variables predicted group status.

RESULTS

Workers who stayed at work despite CMP reported significantly lower levels of fear avoidance (OR = 0.94), pain catastrophizing (OR = 0.93), perceived workload (OR = 0.93), and higher pain acceptance (OR = 1.11), life control (OR = 1.62) and pain self-efficacy (OR = 1.09) compared to sick-listed workers following rehabilitation, even after controlling for confounders. The groups did not differ on physical activity level, active coping and work satisfaction. Group status was predicted best by pain intensity, duration of pain, pain acceptance, perceived workload, mental health, and psychological distress (area under the receiver operating characteristic curve = 0.91, 95% CI = 0.87-0.95).

CONCLUSIONS

A wide range of characteristics of workers who stay at work despite CMP were explored. Relevant differences from sick-listed workers with CMP were observed in all domains of the bio-psycho-social model. Six main predictors were identified that best discriminate between both groups.

Validity of two simple measures for estimating life-course socio-economic position in cross-sectional postal survey data in an older population: results from the North Staffordshire Osteoarthritis Project (NorStOP)

Background

Since few cohorts encompass the whole life-course, many studies that measure socio-economic position (SEP) across the life-course rely on participant recall of SEP measures from cross-sectional postal or interview surveys. It is also particularly important that SEP measures should be appropriate for the age of the population studied, as the level of missing data has been shown to increase in older people. The aim of this study was to investigate the accuracy of recall of two SEP measures in older adults, age left school and longest job, by examining their validity in a general population postal survey in North Staffordshire, UK.

Methods

Sets of questions on education and longest job were included in a questionnaire at different stages of the study. All patients aged 50+ registered with three general practices were sent a baseline Health Questionnaire. 6 years later, 3410 responders were mailed a follow-up Health Questionnaire; a sub-sample of these participants took part in independent qualitative interviews. Validity was assessed by: percentage completion; internal percentage agreement within each set of questions; percentage agreement of qualitative and quantitative data for age left school and longest job; comparing recall of age left school with historical change in legal school leaving age; comparing frequency of pottery job titles with those in 1981 Census data for Stoke-on-Trent.

Results

The adjusted response to different stages of the study was 71–85%. Completion of questions was 83–98%. Internal agreement was 84–97% (education) and 95–100% (longest job). Comparison of survey and interview data showed 86% agreement (± 1 year) for age left school and 91% agreement for longest job. The change in age left school data concurred with the historical shift in legal school leaving age. 11% of job titles were pottery in NorStOP data and 15% in Stoke-on-Trent Census data.

Conclusions

The results from this study provide evidence for the accuracy of recall of two simple measures of SEP (age left school and longest job) in a postal survey of older adults. Consistency with evidence from external datasets indicated the potential validity of these measures for studying life-course SEP in population surveys.

Pain among women: Associations with socio-economic factors over time and the mediating role of depressive symptoms

Background and aims

Lower socioeconomic status (SES), based on economic situation, education and occupation, has been associated with greater morbidity and mortality in a wide range of diseases, and socioeconomic inequalities have been found in several chronic pain populations. Since women are overrepresented in several clinical pain conditions, there is a need to understand the influence of SES among women with pain. In a previous cross-sectional study, socioeconomic-and work conditions were associated with pain among women from the general population of Sweden. In the present study, based on baseline and follow-up measures from 2300 of the same sample, we examined associations between pain variables, socioeconomic status and work conditions over time by means of multiple logistic/linear regression analyses. Additionally, a possible mediating role of depressive symptoms on the relationship between SES and pain was examined.

Methods

The study was a prospective panel survey with two measurements 12 months apart among 2300 women with and without pain from the general population in Stockholm (aged 18–64). Logistic and linear regression analyses were used to identify associations between SES and pain outcomes.

Results

Results revealed that pain is a rather stable condition with large impact on daily functioning among many women. Certain SES variables (educational level, financial strain, occupational level) were related to pain and pain related disability prospectively. Financial strain and to be a blue-collar worker were related to the incidence of pain among all women, while educational level was related to worse pain outcomes among women with pain in terms of pain intensity, pain frequency, number of pain locations and pain-related disability. Symptoms of depression were associated with pain incidence and with pain variables (intensity, number of pain locations and pain-related disability) and with lower SES.

Conclusions

Financial strain and occupational level were here identified as risk factors for the incidence of pain, and could be interpreted as increasing both physical and psychological stress and thereby work both as predisposing the individual to pain and to perpetuate the development of a pain condition. Educational level was associated with the course of pain in terms of pain duration and pain-related disability which may indicate that once affected by pain, lower educational level may be related to less functional coping strategies in the adaptation to the pain condition. Depressive symptoms could be understood as a mediator of the relationship between SES and pain among women in terms of limiting the individual’s strategies to handle pain in a functional manner by increasing passive behavior patterns such as avoidance.

Implications

The interplay between SES and symptoms of depression should be regarded in preventive interventions and in treatment of pain among women. An overall risk-profile in terms of psychosocial and biological factors needs to be assessed early on within pain treatment for women. Increased knowledge of socioeconomic risk factors for long term pain, e.g. low educational level, is needed on all levels among all professionals within the healthcare system in order to facilitate effective communication in the treatment of women with pain.

Interrelationships between education, occupational social class, and income as determinants of disability retirement

AIMS

The association between a low socioeconomic position and disability retirement is established in the literature, but the interrelationships between various subdomains of socioeconomic position are poorly understood. We examined the independent and interdependent effects of education, social class, and income on disability retirement.

METHODS

Using nationally representative register data we followed up over 260,000 Finns aged 30-63 at the end of 1995 for disability retirement from 1996 to 2004. Cox regression analysis was used to calculate hazard ratios (HR) and relative indices of inequality (RII).

RESULTS

Each socioeconomic indicator had a linear negative association with disability retirement. The socioeconomic gradients were stronger in the younger age groups. The effect of education was largely mediated through succeeding social class. Social class was largely explained by preceding education, but was only moderately mediated through income. Income was largely explained by education, and even further by social class. The independent effects of education, social class, and income on disability retirement as measured by the RII were 1.74 (95% CI 1.60-1.90), 1.95 (1.78-2.15), and 1.35 (1.25-1.47) for men and 1.76 (1.61-1.92), 2.14 (1.95-2.34), and 1.14 (1.05-1.24) for women.

CONCLUSIONS

The effects of socioeconomic position on disability retirement may not be fully captured if the pathways between the various subdomains are disregarded. Our results suggest that efforts to delay and prevent disability retirement should focus on lifestyle and cognitive factors associated with education, as well as on factors associated with social class such as working conditions and power resources.

Health-related and sociodemographic risk factors for disability pension due to low back disorders: a 30-year prospective Finnish Twin Cohort Study

OBJECTIVES

To investigate health-related and sociodemographic risk factors for disability pensions (DP) due to low back disorders (LBD).

METHODS

Questionnaire data in 1975 of the Finnish Twin Cohort Study with record linkage to information on DP due to LBD from the official pension registers during follow-up 1975 to 2004 was analyzed with Cox proportional hazard models.

RESULTS

Musculoskeletal pain (Hazards Ratio [HR] = 2.36 to 2.39; 95% CI 1.97 to 2.88), smoking (HR = 1.82; 1.49 to 2.22), frequent analgesics use (HR = 1.67; 1.38 to 2.02), and presence of other chronic disease (HR = 1.44; 1.22 to 1.70) increased the risk for DP due to LBD. Years of education decreased the risk (HR = 0.81; 0.77 to 0.85). Associations remained significant when adjusted for familial background.

CONCLUSIONS

Health-related and sociodemographic risk factors for DP due to LBD can be identified early in life, and they seem independent from familial effects.

Barriers and enablers to returning to work from long-term sickness absence: Part I-A quantitative perspective

BACKGROUND

Long-term sickness absence (LTSA) in the United Kingdom labor market has become a major health issue in recent years. In contrast to short-term sickness absence, rates for LTSA have been on the increase. This paper, part 1 of a two-part paper, identifies individual domain barriers to returning to work (RTW) from LTSA across the work disability timeline in the UK labor market.

METHODS

This is a retrospective cohort study of 6,246 workers from an occupationally diverse Police Force within the UK using a large administrative database. A series of chi-squared analyses were conducted to analyze the between and within group associations. Next, multiple logistic regression analyses using the Enter method were performed to develop a predictive model for RTW and Absence Phase.

RESULTS

Findings substantiated the presence of individual domain barriers to RTW and predictors of RTW outcome and established the absence phase specificity of a number of risk factors of prolonged work disability. In particular, injury/illness especially mental ill health (MIH), physical job demands, sex, and number of episodes of LTSA are significant individual domain barriers to RTW and represent important risk factors for prolonged work disability.

CONCLUSIONS

Duration of work disability is associated with medical diagnosis, especially MIH, physical job demands, sex, and number of LTSA episodes. Findings also support the importance of using the outcome measure of absence phase of risk factors in addition to RTW outcome.

Predictors of shoulder pain and disability index (SPADI) and work status after 1 year in patients with subacromial shoulder pain

Background

Shoulder pain is a common complaint in primary health care and has an unfavourable outcome in many patients. The objectives were to identify predictors for pain and disability (SPADI) and work status in patients with subacromial shoulder pain.

Methods

Secondary analyses of data from a randomized clinical controlled trial were performed. Outcome measures were the absolute values of the combined Shoulder Pain and Disability Index (SPADI) and work status 1 year after treatment with supervised exercises (SE) or radial extracorporeal shockwave therapy (rESWT). Predictors of outcome were investigated using multiple linear regression (SPADI) and logistic regression (work status).

Results

104 patients were included. Low education (≤ 12 years), previous shoulder pain, and a high baseline SPADI score predicted poor results with these variables explaining 29.9% of the variance in SPADI score at 1 year. Low education and poor self-reported health status predicted a work status of "not working": Odds Ratio, OR = 4.3(95% CI (1.3 to 14.9)), p = 0.02 for education, and OR = 1.06 (95% CI (1.0 to 1.1)), p = 0.001 for self-reported health status, respectively. Adjustments for age, gender, and treatment group were performed, but did not change the results.

Conclusion

Education was the most consistent predictor of pain and disability, and work status at 1 year follow-up. Also, baseline SPADI score, previous shoulder pain and self-reported health status predicted outcome.

Trial registration

Clinical trials NCT00653081

Back pain in older male Italian-born immigrants in Australia: the importance of socioeconomic factors

Back pain is common in older people and is associated with functional disability and poor self-rated health. Older persons are under-represented in back pain research, and research on back pain in older persons from ethnic minorities is particularly sparse. We investigated differences in back pain characteristics, effects and medication use in a population-based sample of 335 Italian-born immigrants and 849 Australian-born men aged 70 years and over. There were 189 (62%) Italian-born men and 507 (63%) Australian-born men who reported experiencing back pain in the past 12 months. Despite no difference in the reported prevalence of back pain between the two groups of men, Italian-born men were more likely to report that their pain was frequent, severe and chronic. Italian-born men were also more likely to report having other sites of pain and that they had limited their activities in the past 12 months due to back pain. Despite these differences, the use of analgesic medication was the same in both groups. Multivariate analyses showed that differences in pain characteristics and effects between the two groups of men were explained by socioeconomic factors such as years of education and occupation history.

"Proportion explained": a causal interpretation for standard measures of indirect effect?

The assessment of indirect effects is an important tool for epidemiologists interested in exploring the mechanisms of exposure-disease relations. A standard way of expressing an indirect effect is in terms of the "proportion explained"; this is the proportion of the total effect that is explained by a particular mediator (or set of mediators). There are several ways to calculate the proportion explained, based on both additive and multiplicative models. However, these standard methods (particularly those based on multiplicative models) have been criticized for lacking a causal interpretation. To address this issue, the author uses a framework of potential outcomes to define the indirect effects of interest (natural effects) and assess the correspondence between the natural effects and standard measures. The author finds that standard additive measures represent an unbiased weighted average of the effects of interest; standard multiplicative measures, on the other hand, yield a biased weighted average of these effects. If the investigator is primarily interested in whether or not an indirect effect exists, standard measures for mediation will often yield the correct answer. In contrast, if valid quantification of the indirect effect is desired, counterfactual-based methods should be used.

Level of education and back pain in France: the role of demographic, lifestyle and physical work factors

PURPOSE

To investigate the pathways from level of education to low back pain (LBP) in the adult population, especially concerning the role of physical working constraints, and personal factors (overweight, tobacco consumption, and tallness).

METHODS

The study population consisted of 15,534 subjects from the National Health Survey, with data on LBP, level of education, personal factors, and physical working constraints. Logistic models for LBP (pain more than 30 days during the previous 12 months) were compared in order to check the consistency of the data with specific causal pathways.

RESULTS

Low back pain was strongly associated with level of education. This association was almost completely explained if present or past exposure to tiring work postures and handling of heavy loads were taken into account. For men, the OR for "no diploma", adjusted only for age, was 1.75; it was 1.02 after additional adjustment on physical work factors. Personal factors played also a role, especially overweight for women. Among them, the OR associated with a body mass index = 27 or more was 1.58 after adjustment on all the other factors.

CONCLUSIONS

In this national population the main pathways from education to LBP were through occupational exposure and lifestyle factors.

Risk factors for cardiovascular diseases and diabetes in disability pensioners aged 40--42 years: a cross-sectional study in Norway

AIMS

Few disability pensions at the age of 40 in Norway are granted due to cardiovascular diseases (CVD) or diabetes, but disability pensioners have an excess mortality of these diseases. In this study, we aim to present risk factors for CVD and diabetes in young disability pensioners, compared with persons able to work.

METHODS

A population-based survey of Norwegian men and women aged 40-42 years was conducted in 1997-1999, with 62,778 participants. Disability pensioners (n= 2636) and other non-working persons (n = 5105) were compared with persons able to work. Risk factors were compared in persons without CVD and diabetes.

RESULTS

Prevalence of self-reported CVD and diabetes was markedly higher in disability pensioners than in persons able to work. In persons without these diseases, we found elevations of all measured risk factors were more prevalent in disabled men and women. Myocardial infarction risk was about 50% higher in disability pensioners. Disability pensioners were more physically inactive and obese; they smoked more and had lipid disorders with elevated total cholesterol, low high-density lipoprotein (hdl)-cholesterol and elevated triglycerides. Other non-working persons had less pronounced elevations of most of the risk factors.

CONCLUSIONS

A high proportion of disability pensioners and others not working at the age of 40 had an elevated risk for CVD and diabetes.

Risk factors for sickness absence due to low back pain and prognostic factors for return to work in a cohort of shipyard workers

The purpose of this study was to determine risk factors for the occurrence of sickness absence due to low back pain (LBP) and to evaluate prognostic factors for return to work. A longitudinal study with 1-year follow-up was conducted among 853 shipyard workers. The cohort was drawn around January 2004 among employees in the shipyard industry. Baseline information was obtained by questionnaire on physical and psychosocial work load, need for recovery, perceived general health, musculoskeletal complaints, sickness absence, and health care use during the past year. During the 1-year follow-up for each subject medical certifications were retrieved for information on the frequency and duration of spells of sickness absence and associated diagnoses. Cox regression analyses were conducted on occurrence and on duration of sickness absence with hazard ratios (HR) with 95% confidence interval (95% CI) as measure of association. During the 1-year follow-up period, 14% of the population was on sick leave at least once with LBP while recurrence reached 41%. The main risk factors for sickness absence were previous absence due to a health problem other than LBP (HR 3.07; 95%CI 1.66–5.68) or previous sickness absence due to LBP (HR 6.52; 95%CI 3.16–13.46). Care seeking for LBP and lower educational level also hold significant influences (HR 2.41; 95%CI 1.45–4.01 and HR 2.46; 95%CI 1.19–5.07, respectively). Living with others, night shift and supervising duties were associated with less absenteeism due to LBP. Workers with a history of herniated disc had a significantly decreased rate of returning to work, whereas those who suffered from hand-wrist complaints and LBP returned to work faster. Prior sick leave due to LBP partly captured the effects of work-related physical and psychosocial factors on occurrence of sick leave. Our study showed that individual and job characteristics (living alone, night shift, lower education, sick leave, or care seeking during the last 12 months) influenced the decision to take sick leave due to LBP. An increased awareness of those frequently on sick leave and additional management after return to work may have a beneficial effect on the sickness absence pattern.