Study protocol title: a prospective cohort study of low back pain

Metabolic syndrome among commercial truck drivers: The relationship between condition prevalence and crashes

BACKGROUND

Metabolic syndrome (MetS) is especially prevalent among US truck drivers. However, there has been limited research exploring associations between MetS conditions with roadway crashes among truck drivers. The objective of this paper is to assess relationships between specific combinations of individual MetS components and crashes and near-misses.

METHODS

Survey, biometric, and anthropometric data were collected from 817 truck drivers across 6 diverse US states. Survey data focused on demographics and roadway safety outcomes, and anthropometric/biometric data corresponded to five MetS conditions (waist circumference blood pressure, hemoglobin A1c, triglycerides, and high-density lipoprotein [HDL] cholesterol). Logistic regression was used to calculate odds ratios of lifetime crashes and near-miss 1-month period prevalence associated with: 1) specific MetS conditions regardless of presence or absence of other MetS conditions, and 2) specific MetS conditions and counts of other accompanying MetS conditions.

RESULTS

Hypertension was the MetS characteristic most strongly associated with lifetime crash and 1-month near-miss outcomes, while high triglycerides, low HDL cholesterol, and large waist circumference were most commonly present among groups of conditions associated with crashes and near-misses. Overall, an increasing number of specific co-occurring MetS conditions were associated with higher reporting of roadway crashes.

CONCLUSIONS

Specific combinations and higher prevalence of MetS conditions were associated with increased frequency of reported crashes. Moreover, when the co-occurrence of MetS conditions is aggregated, a dose-response relationship with crashes appears. These results suggest that policy changes and interventions addressing MetS may increase driver health and reduce crash risk.

Evaluating Different Measures of Low Back Pain Among U.S. Manual Materials Handling Workers: Comparisons of Demographic, Psychosocial, and Job Physical Exposure

OBJECTIVE

To examine differences in demographic, psychosocial, and job physical exposure risk factors between multiple low back pain (LBP) outcomes in a prospective cohort of industrial workers.

BACKGROUND

LBP remains a leading cause of lost industrial productivity. Different case definitions involving pain (general LBP), medication use (M-LBP), seeking healthcare (H-LBP), and lost time (L-LBP) are often used to study LBP outcomes. However, the relationship between these outcomes remains unclear.

METHOD

Demographic, health status, psychosocial, and job physical exposure risk factors were quantified for 635 incident-eligible industrial workers. Incident cases of LBP outcomes and pain symptoms were quantified and compared across the four outcomes.

RESULTS

Differences in age, gender, medical history, and LBP history were found between the four outcomes. Most incident-eligible workers (67%) suffered an LBP outcome during follow-up. Cases decreased from 420 for LBP (25.4 cases/100 person-years) to 303 for M-LBP (22.0 cases/100 person-years), to 151 for H-LBP (15.6 cases/100 person-years), and finally to 56 for L-LBP (8.7 cases/100 person-years). Conversely, pain intensity and duration increased from LBP to H-LBP. However, pain duration was relatively lower for L-LBP than for H-LBP.

CONCLUSION

Patterns of cases, pain intensity, and pain duration suggest the influence of the four outcomes. However, few differences in apparent risk factors were observed between the outcomes. Further research is needed to establish consistent case definitions.

APPLICATION

Knowledge of patterns between different LBP outcomes can improve interpretation of research and guide future research and intervention studies in industry.

Associated Risk Factors with Low Back Pain in White-Collar Workers-A Cross-Sectional Study

Objective: The purpose of the study was to compare the pressure pain threshold (PPT) of soft tissue and the curvatures of the spine in a sitting position and to estimate associated physical risk factors with low back pain (LBP) in young adults. Subjects: White-collar workers (n= 139), both women (n = 51) and men (n = 88) were separated into a control group (n = 82) and a low-intensity LBP (NRS < 3) (n = 57). Methods: The PPTs were tested utilizing the Wagner algometer. The curvatures of the spine were measured employing the photogrammetric method. In the logistic regression model, the odds ratio (OR) was estimated with ±95% confidence interval (CI) indicating the probability of the reported LBP. Results: The PPTs of soft tissue (OR = 1.1; CI = 1.02−1.19; p < 0.05) and the angle of the thoracolumbar spine in the everyday, habitual sitting position (OR = 1.19; CI = 1.05−1.34; p < 0.05) were associated with low-intensity LBP in female subjects. Additionally, the low intensity LBP were associated with the angles of the torso (OR = 1.14; CI = 1.01−1.29; p < 0.05) and the lumbosacral spine in the corrected sitting position (OR = 1.06; CI = 0.98−1.15; p > 0.05) and BMI (OR = 1.56; CI = 0.84−2.90; p > 0.05) in male subjects. Conclusion: Individual risk factors were associated with the low-intensity LBP only in females utilizing the PPT and the thoracolumbar angle in the habitual sitting position study factors. Men from the LBP group did not effectively correct the lumbosacral angle. Therefore, re-educated, self-corrected posture with specific postural training would be expected to improve proprioception in postural control capacity and result in decreasing pain.

Metabolic Syndrome in Commercial Truck Drivers: Prevalence, Associated Factors, and Comparison With the General Population

INTRODUCTION

Commercial motor vehicle drivers, such as truck drivers, experience unique health, lifestyle, and occupational challenges directly associated with their profession.

METHODS

All participants in this multistate cross-sectional study completed questionnaire measurements. Participants were categorized with metabolic syndrome (MetS) if they had at least three of the five modified criteria used in the joint scientific statement on metabolic syndrome.

RESULTS

Overall MetS prevalence was 52.4% (n = 428) of the 817 participants. Prevalence of MetS criteria were waist circumference (n = 634, 77.0%), low HDL cholesterol (n = 580, 71.0%), elevated triglycerides (n = 552, 67.6%), elevated blood pressure (n = 175, 21.2%), and elevated hemoglobin A1c (n = 97, 11.9%). Truck drivers were 2.7 times more likely to have MetS compared to the general working population.

CONCLUSION

Truck drivers in the United States have a high prevalence of MetS compared to the general working population.

Psychosocial Factors and Low Back Pain Outcomes in a Pooled Analysis of Low Back Pain Studies

OBJECTIVE

Assessment of possible relationships between work-related psychosocial measures and self-reported low back pain (LBP) outcomes in a large pooled dataset of 1929 participants from 82 facilities in the United States.

METHODS

Pooled data from three prospective cohort studies were used to calculate odds ratios (OR) and 95% confidence intervals (95% CI) for relationships between psychosocial factors and the LBP outcomes. Personal and occupational confounders were controlled for in adjusted Logistic regression models.

RESULTS

Supervisor support and job satisfaction were significantly (P < 0.05) related to all three LBP outcomes. Other psychosocial factors were significantly (P < 0.05) associated with at least one of the LBP outcomes. Adjusted ORs ranged from approximately 1.50 to 3.50 for most associations.

CONCLUSIONS

There is a significant relationship between work-related psychosocial measures and LBP outcomes.

The Quebec Low Back Pain Study: a protocol for an innovative 2-tier provincial cohort

INTRODUCTION

The neurobiological mechanisms underlying recovery from or persistence of low back pain (LBP) remain misunderstood, limiting progress toward effective management. We have developed an innovative two-tier design to study the transition from acute to chronic LBP. The objective of the first tier is to create a provincial web-based infrastructure to recruit and monitor the trajectory of individuals with acute LBP. The objective of the second tier is to fuel hypothesis-driven satellite data collection centers with specialized expertise to study the role of biomechanical, epigenetic, genetic, neuroanatomical, ontological, physiological, psychological, and socioeconomic factors in LBP chronicity.

METHODS

This article describes the first tier of the protocol: establishment of the Core Dataset and Cohort. Adults with acute LBP will be recruited through networks, media, and health care settings. A web-based interface will be used to collect self-reported variables at baseline and at 3, 6, 12, and 24 months. Acute LBP will be defined according to the Dionne 2008 consensus. Measurements will include the Canadian minimum data set for chronic LBP research, DN4 for neuropathic pain, comorbidities, EQ-5D-5L for quality of life, and linkage with provincial medico-administrative databases. The primary outcome will be the transition to chronic LBP, as defined by Deyo 2014. Secondary outcomes include health care resource utilization, disability, sick leave, mood, and quality of life.

PERSPECTIVE

This study brings together diverse research expertise to investigate the transition from acute to chronic LBP, characterize the progression to recovery or chronicity, and identify patterns associated with that progression.

Association Between Exercise and Low Back Pain Resulting in Modified Duty and Lost Time: A Cross-Sectional Analysis of an Occupational Population

OBJECTIVE

The aim of the study was to assess the relationship between leisure time exercise and whether workers ever had modified duty or lost time (MD/LT) due to low back pain (LBP) in an occupational cohort.

METHODS

Workers (N = 827) completed a structured interview assessing characteristics of their LBP, whether or not the pain caused modified or lost work time, and their participation in leisure time exercise. Odds ratio of modified/lost time and minutes of exercise participation were assessed.

RESULTS

Workers who participated in over 316 min/wk of leisure time exercise incurred significantly less modified/lost time, adjusted odds ratio = 0.46 (95% confidence interval, 0.23 to 0.98). There also lies a significant trend between increases in leisure time exercise and reductions in modified/lost time (P = 0.0016).

CONCLUSION

These results suggest exercise reduces risk of MD/LT from LBP.

Psychosocial Factors Related to Lateral and Medial Epicondylitis: Results From Pooled Study Analyses

OBJECTIVE

The goal is to assess the relationships between psychosocial factors and both medial and lateral epicondylitis after adjustment for personal and job physical exposures.

METHODS

One thousand eight hundred twenty-four participants were included in pooled analyses. Ten psychosocial factors were assessed.

RESULTS

One hundred twenty-one (6.6%) and 34 (1.9%) participants have lateral and medial epicondylitis, respectively. Nine psychosocial factors assessed had significant trends or associations with lateral epicondylitis, the largest of which was between physical exhaustion after work and lateral epicondylitis with and odds ratio of 7.04 (95% confidence interval = 2.02 to 24.51). Eight psychosocial factors had significant trends or relationships with medial epicondylitis, with the largest being between mental exhaustion after work with an odds ratio of 6.51 (95% confidence interval = 1.57 to 27.04).

CONCLUSIONS

The breadth and strength of these associations after adjustment for confounding factors demonstrate meaningful relationships that need to be further investigated in prospective analyses.

Effect of Sacroiliac Joint Mobilization on the Level of Soft Tissue Pain Threshold in Asymptomatic Women

OBJECTIVE

This study aimed to evaluate the effect of sacroiliac joint (SIJ) mobilization and/or self-mobilization on the level of soft tissue pain threshold in 21- to 23-year-old asymptomatic women (n = 20).

METHODS

The FPIX Wagner Algometer was applied to compute the pressure pain threshold (PPT) over the right and left side of the iliolumbar ligament and lumbar erector spinae (L3). Measurements were taken of the right SIJ before and after a randomized protocol of oscillating mobilization, self-mobilization, and placebo treatment.

RESULTS

A main effect of intervention (mobilization, self-mobilization, placebo) was confirmed by analysis of variance, with increases in PPT over the iliolumbar ligament (F = 13.04, P < .05) and erector spinae (F = 12.28, P < .05) on the mobilized side. The Wilcoxon test indicated that SIJ mobilization increased PPT over the iliolumbar ligament (P < .05) and erector spinae (P < .05) on both sides. Self-mobilization increased erector spinae PPT on the exercised side (P < .05), whereas the placebo did not cause any changes in PPT (P > .05).

CONCLUSION

The study provides evidence of local and global pain modulation resulting from oscillatory mobilization of the SIJ in women without pain symptoms. Self-mobilization of the SIJ has limited analgesic application.

Two industrial cohorts: baseline characteristics and factors associated with obesity

OBJECTIVE

To describe demographic and health characteristics, and factors associated with obesity among production workers.

METHODS

This cross-sectional study analyzed baseline data from two occupational cohorts. Regression modeling was used to assess associations between worker characteristics and obesity.

RESULTS

A total of 1974 subjects were included in these analyses. The mean body mass index was 29.5 kg/m (SD = 6.5). Having smoked in the past and currently smoking decreased the odds of being obese in the WISTAH Distal Upper Extremity cohort, whereas those feeling depressed had increased odds of being obese. Being a Pacific Islander/Native Hawaiian and married increased the odds of obesity in the BackWorks Low Back Pain cohort.

CONCLUSIONS

Factors associated with obesity differed substantially between the two cohorts. Recognizing factors associated with obesity in specific work settings may provide opportunities for optimizing preventive workplace interventions.

Associations between Distal Upper Extremity Job Physical Factors and Psychosocial Measures in a Pooled Study

Introduction. There is an increasing body of literature relating musculoskeletal diseases to both job physical exposures and psychosocial outcomes. Relationships between job physical exposure measures and psychosocial factors have not been well examined or quantified. These exploratory analyses evaluate relationships between quantified exposures and psychosocial outcomes. Methods. Individualized quantification of duration, repetition, and force and composite scores of the Strain Index (SI) and the Threshold Limit Value for Hand Activity Level (TLV for HAL) were compared to 10 psychosocial measures. Relationships and predicted probabilities were assessed using ordered logistic regression. Analyses were adjusted for age, BMI, and gender. Results and Discussion. Among 1834 study participants there were multiple statistically significant relationships. In general, as duration, repetition, and force increased, psychosocial factors worsened. However, general health and mental exhaustion improved with increasing job exposures. Depression was most strongly associated with increased repetition, while physical exhaustion was most strongly associated with increased force. SI and TLV for HAL were significantly related to multiple psychosocial factors. These relationships persisted after adjustment for strong confounders. Conclusion. This study quantified multiple associations between job physical exposures and occupational and nonoccupational psychosocial factors. Further research is needed to quantify the impacts on occupational health outcomes.

Predictors Associated With Changes of Weight and Total Cholesterol Among Two Occupational Cohorts Over 10 Years

OBJECTIVE

To ascertain worker health characteristics and psychosocial factors associated with changes in body weight and total cholesterol (TC) among two production operation populations.

METHODS

We performed descriptive and predictive analysis of questionnaire data and biomedical measurements from two prospective cohort studies. Our key outcomes were changes in weight, and TC over 5 to 10 years between baseline and exit assessments.

RESULTS

A total of 146 subjects were analyzed. Increases in weight were associated with belief in being overweight and baseline overweight and obesity. Increases in TC levels were associated with female sex, belief that TC levels were "not good," and feeling depressed.

CONCLUSIONS

Most of the reported associations with increases in weight and TC levels are amenable to interventions and may be a target for workplace intervention programs.

Developments in intervertebral disc disease research: pathophysiology, mechanobiology, and therapeutics

Low back pain is a leading cause of disability worldwide and the second most common cause of physician visits. There are many causes of back pain, and among them, disc herniation and intervertebral disc degeneration are the most common diagnoses and targets for intervention. Currently, clinical treatment outcomes are not strongly correlated with diagnoses, emphasizing the importance for characterizing more completely the mechanisms of degeneration and their relationships with symptoms. This review covers recent studies elucidating cellular and molecular changes associated with disc mechanobiology, as it relates to degeneration and regeneration. Specifically, we review findings on the biochemical changes in disc diseases, including cytokines, chemokines, and proteases; advancements in disc disease diagnostics using imaging modalities; updates on studies examining the response of the intervertebral disc to injury; and recent developments in repair strategies, including cell-based repair, biomaterials, and tissue engineering. Findings on the effects of the omega-6 fatty acid, linoleic acid, on nucleus pulposus tissue engineering are presented. Studies described in this review provide greater insights into the pathogenesis of disc degeneration and may define new paradigms for early or differential diagnostics of degeneration using new techniques such as systemic biomarkers. In addition, research on the mechanobiology of disease enriches the development of therapeutics for disc repair, with potential to diminish pain and disability associated with disc degeneration.

Prevalence of low back pain by anatomic location and intensity in an occupational population

Background

Low Back Pain (LBP) is a common and costly problem, with variation in prevalence. Epidemiological reports of rating of pain intensity and location within the low back area are rare. The objective is to describe LBP in a large, multi-center, occupational cohort detailing both point and 1-month period prevalence of LBP by location and intensity measures at baseline.

Methods

In this cross-sectional report from a prospective cohort study, 828 participants were workers enrolled from 30 facilities performing a variety of manual material handling tasks. All participants underwent a structured interview detailing pain rating and location. Symptoms in the lower extremities, demographic and other data were collected. Body mass indices were measured. Outcomes are pain rating (0–10) in five defined lumbar back areas (i) LBP in the past month and (ii) LBP on the day of enrollment. Pain ratings were reported on a 0–10 scale and subsequently collapsed with ratings of 1–3, 4–6 and 7–10 classified as low, medium and high respectively.

Results

172 (20.8%) and 364 (44.0%) of the 828 participants reported pain on the day of enrollment or within the past month, respectively. The most common area of LBP was in the immediate paraspinal area with 130 (75.6%) participants with point prevalence LBP and 278 (77.4%) with 1-month period prevalence reported having LBP in the immediate paraspinal area. Among those 364 reporting 1-month period prevalence pain, ratings varied widely with 116 (31.9%) reporting ratings classified as low, 170 (46.7%) medium and 78 (21.4%) providing high pain ratings in any location. Among the 278 reporting 1-month period prevalence pain in the immediate paraspinal area, 89 (32.0%) reported ratings classified as low, 129 (46.4%), medium and 60 (21.6%) high pain ratings.

Conclusions

Pain ratings varied widely, however less variability was seen in pain location, with immediate paraspinal region being the most common. Variations may suggest different etiological factors related to LBP. Aggregation of different locations of pain or different intensities of pain into one binary classification of LBP may result in loss of information which may potentially be useful in prevention or treatment of LBP.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2474-15-283) contains supplementary material, which is available to authorized users.

Low-back pain ratings for lifetime, 1-month period, and point prevalences in a large occupational population

OBJECTIVE

This manuscript systematically quantifies multiple measures of low-back pain (LBP) prevalence by pain rating in a large, multisite cohort of workers.

BACKGROUND

Published LBP prevalence rates vary. Studies rely on one measure of LBP and none report prevalence stratified by pain rating.

METHOD

Cross-sectional analyses of baseline data from a multicenter prospective cohort study were performed to evaluate differences in lifetime prevalence, 1-month period prevalence, and point prevalence of LBP. Workers were from 28 different employment settings in 4 diverse U.S. states. All workers completed computerized questionnaires and structured interviews. LBP prevalence measures were stratified by pain ratings.

RESULTS

A total of 828 subjects had complete health data at baseline. Lifetime prevalence, 1-month period prevalence, and point prevalence for any LBP (> or = 1/10) were 63.4%, 44.0%, and 20.8% respectively. Prevalence of LBP decreased with increasing pain ratings. As an example, using a threshold of LBP > or = 3/10 pain, prevalence measures were 61.0%, 37.6%, and 16.7% respectively. A threshold of LBP > or = 5/10 had prevalence measures of 51.2%, 22.9%, and 9.9% respectively. Age, systolic and diastolic blood pressure, high cholesterol, high blood pressure, and tobacco use were statistically significantly related to lifetime prevalence of LBP.

CONCLUSION

Lifetime LBP prevalence, 1-month period prevalence, and point prevalence stratified by pain ratings demonstrate a wide variation of prevalence measures of LBP and self-reported pain ratings. Higher pain rating thresholds yield lower prevalence measures and may impact assessments of risk factors. Differences in pain ratings may allow for focused surveillance within an occupational cohort.