The influence of personal variables on work-related low-back disorders and implications for future research

A pilot study to assess a risk of a high-risk group of low back pain membership in workers who perform the manual material handling tasks

BACKGROUND

We conducted this experimental study to estimate a risk of a high-risk group of low back pain (LBP) membership in workers who perform the manual material handling (MMH) tasks in an actual workplace setting.

METHODS

The subjects include healthy workers who were engaged in 12 MMH tasks at 6 manufacturing companies. We assessed the dynamic motion of trunk or lumbar spine using an industrial lumbar motion monitor (BioDynamics Laboratory of Ohio State University). The subjects were evaluated for the age, gender, years of working and anthropometric measurements (e.g., height, weight, shoulder height, elbow height, iliac height, leg length, trunk length, trunk circumference, iliac width, iliac depth, xiphoid width and xiphoid depth). Moreover, they were also evaluated for a risk of a high-risk group of LBP membership based on lift frequency, average twisting velocity, maximum moment, maximum sagittal flexion and maximum lateral velocity.

RESULTS

The subjects who were engaged in a packaging at a detergent manufacturing company are at the greatest risk of LBP (63.76%). This was followed by packaging at a leather product manufacturing company (57.06%), packaging at a non-metallic casting material manufacturing company (57.03%), manual injection at a non-metallic casting material manufacturing company (52.00%), toggling at a leather product manufacturing company (46.09%), non-metallic casting material manufacturing company (42.88%), rolling at a non-metallic mineral product manufacturing company (42.12%), shooting at a non-metallic casting material manufacturing company (40.99%), vacuum processes at a leather product manufacturing company (35.00%), looping at a general industrial machinery manufacturing company (33.93%), setting at a leather product manufacturing company (30.22%) and packaging at a general metal product manufacturing company (22.02%).

CONCLUSIONS

Our approach indicates that there is a risk of a high-risk group of LBP membership in workers who perform the MMH tasks.

Factors associated with low back pain among construction workers in Nepal: A cross-sectional study

BACKGROUND

Low back pain (LBP) is the commonest cause of disability throughout the world. This study aimed to determine the prevalence and factors associated with LBP among the construction workers in Nepal.

METHODS

A community-based cross-sectional study was conducted among the construction workers working in Banepa and Panauti municipalities of Kavre district, from September 2019 to February 2020. Data was collected purposively by face-to-face interview from 402 eligible participants from the both municipalities using semi-structured questionnaire. Mobile-based data collection was done using KoboCollect. Data were exported to and analysed using R-programming software (R-3.6.2). Univariate and multivariate logistic regressions were performed. All tests were two tailed and performed at 95% confidence interval (CI).

RESULT

One-year prevalence of LBP among construction workers were 52.0% (95%CI: 47.0-57.0). The higher odds of LBP was reported among females [adjusted odds ratio (aOR) = 2.42; 95%CI: 1.12-5.23], those living below poverty-line (aOR = 2.35; 95%CI: 1.32-4.19), participants with more than five years of work experience (aOR = 1.66; 95%CI: 1.01-2.73) and those with intermediate sleep quality (aOR = 2.06; CI: 1.03-4.11). About 80.0% of construction workers with LBP never seek healthcare services due to: a) time constraints (90.9%), b) financial constraints (18.1%) and c) fear of losing wages on seeking healthcare services (40.9%). The majority of the participants (94.8% among those without LBP and 72.3% among those with LBP) did nothing to prevent or manage LBP.

CONCLUSION

The prevalence of LBP in the past one year was high among construction workers where majority of workers never did anything to prevent or manage LBP. Therefore, the public health professionals should set up the health promotion, education, and interventions aimed at increasing awareness on preventive techniques and predisposing factors of LBP.

Risk factors of low back pain and the relationship with sagittal vertebral alignment in Tanzania

Background

LBP is a common and serious problem affecting vast populations of the world. However, only few studies on LBP in sub-Saharan Africa have been conducted. Studies report that LBP and pelvic angle are interrelated, and African residents have a high pelvic tilt. The strategy to prevent LBP should focus on activities that promote holistic health. For that purpose, it is important to grasp the state of LBP and how it affects people’s lifestyle in Tanzania to clarify the direction of implementation of physiotherapy treatment and reduce the incidences of LBP among adults. This study aimed to investigate the prevalence and presentation of low back pain (LBP) and the relationship between anthropometric measurements and LBP among people in Moshi city, Kilimanjaro region Tanzania.

Methods

Following signing consent forms, participants were given questionnaires regarding LBP and then grouped accordingly into either asymptomatic or symptomatic cohorts. Anthropometric measurements of participants’ height, weight, curvature of the spine, and pelvic angle were obtained.

Results

A Mann-Whitney U test analysis showed a significant difference in pelvic angle, body mass index (BMI), and thoracic kyphosis angle between the asymptomatic group and the symptomatic group. No significant differences in lumbar lordosis angle or abdominal muscle strength were found between the two groups.

Conclusions

A person with symptomatic LBP in Tanzania has a large anteversion of the pelvic tilt and a thoracic kyphotic posture. This study shows a relationship between sagittal spinal alignment and LBP in Tanzania, which could allow for prospective identification of subjects prone to developing LBP in the future.

Risk Profiles for Four Types of Work-Related Injury among Hospital Employees

In this retrospective case-control study, researchers examined risk factors for four types of work-related injury (WRI) in hospital employees. Data were collected from employee health charts and computer databases ( N = 2050) and analyzed using logistic regression. Study results showed that strain injuries were related to increased age, increased body mass index (BMI), and maintenance, custodial, and direct-caregiver employment types. Repetitive motion injuries were related to increased BMI and clerical and custodial employment types. Exposure/reaction injuries were related to increased age, increased BMI, and maintenance, custodial, and direct-caregiver employment types. Contact/assault injuries were related to increased age, increased BMI, and maintenance, custodial, and direct-caregiver employment types. All injury types were most often related to female gender and full-time employment status. Reformulating policies to improve screening, prevention, and education for those at risk for certain injury types may limit WRI occurrences and costs.

Factors Associated with Work-Related Injury among Hospital Employees

The Central Arkansas Veterans Healthcare System (CAVHS) spends $1 million annually on occupational illnesses and injuries. To address the problem of injuries among hospital employees, a retrospective case-control study was conducted to examine select risk factors for work-related injuries (WRI) among CAVHS employees. Study methods included a review of employee health charts and computer and manual databases from 1997 to 2002 ( N = 2,050). The researchers found that WRI increased with age; WRI occurred more often in women than in men; WRI was greater among maintenance and custodial staff compared to direct caregivers, and less among clerical staff; WRI occurred less often in part-time than full-time staff; and WRI increased with increasing body mass index. Developing standards, guidelines, and policies for preplacement screening, preventive measures, training, and education may help to minimize WRI and associated costs.

Field Evaluation of the Revised Niosh Lifting Equation

The preliminary results of a prospective epidemiological study of the revised NIOSH lifting equation are presented. The baseline evaluations included assessment of lifting and lowering tasks with the revised NIOSH equation, as well as a questionnaire regarding personal variables. Subject follow-up was primarily accomplished through postal questionnaires, telephone interviews, and surveillance for workers' compensation claims for low-back disorders. The preliminary results reported are based on approximately 375 person-years of exposure; however, the follow-up period is still in progress. Important findings related to the usability of the revised NIOSH equation across several types of common exposures are also discussed.

Psychological factors: anxiety, depression, and somatization symptoms in low back pain patients

Aim

To determine the prevalence of low back pain (LBP), investigate the sociodemographic characteristics of patients with LBP, and examine its association with psychological distress such as anxiety, depression, and somatization.

Subjects and methods

Of the 2742 patients approached, 2180 agreed to participate in this cross-sectional study (79.5% response rate). The survey was conducted among primary health care visitors from March to October 2012 and collected sociodemographic details and LBP characteristics. General Health Questionnaire-12 was used to identify the probable cases. Anxiety was assessed with Generalized Anxiety Disorder-7, depression was assessed with Patient Health Questionnaire-9, and somatization was measured with Patient Health Questionnaire-15.

Results

The study sample consisted of 52.9% males and 47.1% females. The prevalence of LBP was 59.2%, comprising 46.1% men and 53.9% women. LBP was significantly higher in Qataris (57.9%), women (53.9%), housewives (40.1%), and individuals with higher monthly income (53.9%). Somatization (14.9%) was observed more in LBP patients, followed by depression (13.7%) and anxiety disorders (9.5%). The most frequently reported symptoms were “headaches” (41.1%) and “pain in your arms, legs, or joints” (38.5%) in LBP patients with somatization. The most frequent symptoms among depressed LBP patients were “thinking of suicide or wanting to hurt yourself” (51.4%) and “feeling down, depressed, or hopeless” (49.2%). “Not being able to stop or control worrying” (40.2%), “worrying too much about different things” (40.2%), and “feeling afraid as if something awful might happen” (40.2%) were the most common anxiety symptoms in LBP patients. Psychological distress such as anxiety (9.5% versus 6.2%), depression (13.7% versus 8.5%), and somatization (14.9% versus 8.3%) were significantly higher in LBP patients.

Conclusion

The prevalence of LBP in this study sample was comparable with other studies. Furthermore, psychological distress such as anxiety, depression, and somatization were more prevalent in LBP patients compared to patients without LBP.

Predictors of low back pain in physically active conscripts with special emphasis on muscular fitness

BACKGROUND CONTEXT

Association between low physical fitness and low back pain (LBP) is contradictory in previous studies.

PURPOSE

The objective of the present prospective cohort study was to investigate the predictive associations of various intrinsic risk factors in young conscripts for LBP, with special attention to physical fitness.

STUDY DESIGN

A prospective cohort study.

PATIENT SAMPLE

A representative sample of Finnish male conscripts. In Finland, military service is compulsory for male citizens and 90% of young men enter into the service.

OUTCOME MEASURES

Incidence of LBP and recurrent LBP prompting a visit at the garrison health clinic during 6-month military training.

METHODS

Four successive cohorts of 18- to 28-year-old male conscripts (N=982) were followed for 6 months. Conscripts with incidence of LBP were identified and treated at the garrison clinic. Predictive associations between intrinsic risk factors and LBP were examined using multivariate Cox proportional hazard models.

RESULTS

The cumulative incidence of LBP was 16%, the incidence rate being 1.2 (95% confidence interval [CI], 1.0-1.4) per 1,000 person-days. Conscripts with low educational level had increased risk for incidence of LBP (hazard ratio [HR], 1.6; 95% CI, 1.1-2.3). Conscripts with low dynamic trunk muscle endurance and low aerobic endurance simultaneously (ie, having coimpairment) at baseline also had an increased risk for incidence of LBP. The strongest risk factor was coimpairment of trunk muscular endurance in tests of back lift and push-up (HR, 2.8; 95% CI, 1.4-5.9).

CONCLUSIONS

The increased risk for LBP was observed among young men who had a low educational level and poor fitness level in both muscular and aerobic performance.

The greatest risk for low-back pain among newly educated female health care workers; body weight or physical work load?

Background

Low back pain (LBP) represents a major socioeconomic burden for the Western societies. Both life-style and work-related factors may cause low back pain. Prospective cohort studies assessing risk factors among individuals without prior history of low back pain are lacking. This aim of this study was to determine risk factors for developing low back pain (LBP) among health care workers.

Methods

Prospective cohort study with 2,235 newly educated female health care workers without prior history of LBP. Risk factors and incidence of LBP were assessed at one and two years after graduation.

Results

Multinomial logistic regression analyses adjusted for age, smoking, and psychosocial factors showed that workers with high physical work load had higher risk for developing LBP than workers with low physical work load (OR 1.8; 95% CI 1.1–2.8). In contrast, workers with high BMI were not at a higher risk for developing LBP than workers with a normal BMI.

Conclusion

Preventive initiatives for LBP among health care workers ought to focus on reducing high physical work loads rather than lowering excessive body weight.

A critical review on physical factors and functional characteristics that may explain a sex/gender difference in work-related neck/shoulder disorders

The objective of this paper is to critically review recent literature on physical and functional sex/gender (s/g) differences, with focus on physical determinants associated with neck/shoulder musculoskeletal injuries. It is well known that there are s/g differences in anthropometrical and functional body characteristics (e.g. size and strength). However, s/g differences may be wrongly attributed if data analysis does not include appropriate corrections (e.g. by strength for endurance). Recent literature on motor control shows that there may indeed be s/g differences in muscle coordination and movement strategies during upper limb tasks that are not currently explained by methodological inadequacies. Moreover, recent studies have shown differences between men and women in sensory hypersensitivity characteristics associated with neck/shoulder injuries. Taken together, the literature points to the importance of accounting for possible s/g differences at all levels of the biopsychosocial system in order to better understand sex- and gender-specific issues relevant to workplace health.

PRACTITIONER SUMMARY

This article critically reviews recent literature and a conceptual model highlighting s/g differences in physical and functional characteristics related to neck/shoulder musculoskeletal disorders (NSMSD). Findings have implications on understanding how personal factors may affect NSMSD risk. With better understanding, practitioners can make more appropriate decisions to prevent work-related NSMSD.

A prospective study of neck, shoulder, and upper back pain among technical school students entering working life

PURPOSE

The aim of this prospective study was to relate the prevalence of neck, shoulder, and upper back pain to occupational and individual risk factors among a population of technical school students in their transition from school to working life. In addition, we wanted to assess the changes in pain prevalence during follow-up.

METHODS

A cohort consisting of 173 technical school students was followed up during a 3-year period, from their last year of school through their first years of working life. Data on self-reported neck, shoulder, and upper back pain and factors such as mechanical exposure, perceived stress, and physical activity in leisure time were collected.

RESULTS

A high prevalence of pain in the neck, shoulder, and upper back among the technical school students was found. There were however few students reporting severe pain. Reporting pain at baseline gave over three times higher risk of reporting it at follow-up. A high level of physical activity outside working hours gave a lower risk of reporting neck, shoulder, and upper back pain at follow-up. High and moderate levels of mechanical exposure and high stress level were not found to be risk factors for pain after entering working life.

CONCLUSION

Neck, shoulder, and upper back pain are common among adolescents and may persist into working life. These results may give potential for preventive efforts at a young age. There is still much uncertainty about the factors leading to musculoskeletal pain, and more research is needed on this topic.

Biomechanical effects of sitting with adjustable ischial and lumbar support on occupational low back pain: evaluation of sitting load and back muscle activity

Background

Compared to standing posture, sitting decreases lumbar lordosis, increases low back muscle activity, disc pressure, and pressure on the ischium, which are associated with occupational LBP. A sitting device that reduces spinal load and low back muscle activities may help increase sitting comfort and reduce LBP risk. The objective of this study is to investigate the biomechanical effect of sitting with a reduced ischial support and an enhanced lumbar support (Off-Loading) on load, interface pressure and muscle activities.

Methods

A laboratory test in low back pain (LBP) and asymptomatic subjects was designed to test the biomechanical effect of using the Off-Loading sitting posture. The load and interface pressure on seat and the backrest, and back muscle activities associated with usual and this Off-Loading posture were recorded and compared between the two postures.

Results

Compared with Normal (sitting upright with full support of the seat and flat backrest) posture, sitting in Off-Loading posture significantly shifted the center of the force and the peak pressure on the seat anteriorly towards the thighs. It also significantly decreased the contact area on the seat and increased that on the backrest. It decreased the lumbar muscle activities significantly. These effects are similar in individuals with and without LBP.

Conclusion

Sitting with reduced ischial support and enhanced lumbar support resulted in reduced sitting load on the lumbar spine and reduced the lumbar muscular activity, which may potentially reduce sitting-related LBP.

Toward the development of predictive equations of back muscle capacity based on frequency- and temporal-domain electromyographic indices computed from intermittent static contractions

BACKGROUND CONTEXT

Back muscles capacity is impaired in chronic low back pain patients but no motivation-free test exists to measure it. A functional endurance test (FET) was used to assess capacity of back muscles using surface electromyographic (EMG) indices as outcome measures.

PURPOSE

The main objective of the present study was to explore the possibility of combining different types of EMG indices to predict absolute endurance and strength.

STUDY DESIGN/SETTING

A cross-sectional study using a repeated measures design in laboratory setting.

METHODS

Healthy subjects (44 men and 29 women) performed maximal voluntary contractions (Strength criterion: extension moment at L5/S1) and a fatigue test involving intermittent static extension contractions to exhaustion (Tend endurance criterion: time to reach exhaustion). Surface EMG signals were collected from four pairs of back muscles. From the first 5 minutes (women) or 10 minutes (men) of EMG data, frequency- and temporal-domain analyses were applied to compute various EMG indices.

RESULTS

Strength values ranged from 153 to 508Nm, whereas Tend values ranged from 3 to 57 minutes across the subjects. Gender-specific multiple regression equations were developed, using the retained EMG indices from the four electrode sites, to predict Tend (men: R(2)=0.76, error=9%; women: R(2)=0.70, error=17%) and Strength (men: R(2)=0.72, error=9%; women: R(2)=0.25, error=13%).

CONCLUSIONS

It appears to be possible to predict the capacity of back muscles using an intermittent and time-limited (submaximal) fatigue task. Frequency- and temporal-domain EMG indices were shown to provide complementary information in this respect. This FET has potential to better infer back muscle capacity for realistic occupational tasks because more specific muscle fatigue mechanisms are involved.

Biopsychosocial factors are associated with low back pain in female nursing students: a cross-sectional study

BACKGROUND

Occupational low back pain is a significant problem among nurses. Recent literature suggests current occupational preventative strategies for nurses have not been effective. Given low back pain is already prevalent before commencing employment, nursing students should be the target of preventative interventions. Modifiable personal factors which contribute to low back pain have proven difficult to identify, but are thought to play an important role in the biopsychosocial nature of low back pain.

OBJECTIVES

To evaluate the contribution of personal biopsychosocial factors to low back pain in nursing students.

DESIGN

Cross-sectional study comprising physical testing and questionnaires.

SETTINGS

Two university undergraduate nursing schools in Western Australia.

PARTICIPANTS

170 female undergraduate nursing students.

METHODS

Low back pain and control subjects were compared across social, lifestyle (physical activity), psychological (stress, anxiety, depression, back pain beliefs, coping strategies and catastrophising) and physical (spinal postures and spinal kinematics in functional tasks, leg and back muscle endurance, spinal repositioning error and cardiovascular fitness) characteristics. Low back pain was considered as either "minor" or "significant" depending upon pain severity, duration, impact and level of disability.

RESULTS

Over 30% of all subjects (mean age 22.5+/-4.5 years) reported "significant" low back pain in the preceding 12 months. Univariate analysis: social measures did not distinguish between groups. Subjects with "significant" low back pain were more physically active (p=0.04), had higher stress scores (p=0.01) and used passive coping strategies (p<0.001) more than other subjects. "Significant" low back pain subjects held their lower lumbar spine in a more extended posture during transfers at bed height than other subjects. No differences between groups were found for sagittal spinal mobility, static spinal posture, muscle endurance, spinal repositioning error, cardiovascular fitness or other psychological measures. Multivariate analysis: regression analysis revealed stress, coping, physical activity, spinal kinematics, and age all contributed independently to the presence of low back pain, representing a significant 23% of variance.

CONCLUSIONS

Modifiable lifestyle, psychological and physical factors were independently associated with low back pain in nursing students. Targeting personal factors associated with low back pain in nursing students, rather than occupational factors in working nurses may help improve the impact of low back pain in nurses. Prospective studies are required to confirm the relevance of these findings for risk of future low back pain in nurses.

The assessment of back muscle capacity using intermittent static contractions. Part I – Validity and reliability of electromyographic indices of fatigue

INTRODUCTION

Back muscle capacity is impaired in chronic low back pain patients but no motivation-free test exists to measure it. The aims of this study were to assess the reliability and criterion validity of electromyographic indices of muscle fatigue during an intermittent absolute endurance test.

METHODS

Healthy subjects (44 males and 29 females; age: 20-55 yrs) performed three maximal voluntary contractions (MVC) and a fatigue test while standing in a static dynamometer. Surface EMG signals were collected from four pairs of back muscles (multifidus at the L5 level, iliocostalis lumborum at L3, and longissimus at L1 and T10). The fatigue test, assessing absolute endurance (90-Nm torque), consisted in performing an intermittent extension task to exhaustion. Strength was defined as the peak MVC whereas our endurance criterion was defined as the time to reach exhaustion (Tend) during the fatigue test. From the first five min (females) or ten min (males) of EMG data, frequency and time-frequency domain analyses were applied to compute various spectral indices of muscle fatigue.

RESULTS

The EMG indices were more reliable when computed from the time-frequency domain than when computed from the frequency domain, but showed comparable correlation results (criterion validity) with Tend and Strength. Some EMG indices reached moderate to good correlation (range: 0.64-0.69) with Tend, lower correlations (range: 0.39-0.55) with Strength, and good to excellent between-day test-retest reliability results (intra-class correlation range: 0.75-0.83). The quantification of the spectral content more locally in different frequency bands of the power spectrum was less valid and reliable than the indices computed from the entire power spectrum. Differences observed among muscles were interpreted in light of specific neuromuscular activation levels that were observed during the endurance test. These findings supported the use of an intermittent and time-limited (5-10min) absolute endurance test, that is a practical way to assess the back capacity of chronic low back pain subjects, to assess absolute endurance as well as strength with the use of electromyographic indices of muscle fatigue.

Does body mass index increase the risk of low back pain in a population exposed to whole body vibration?

The aim of this study was to determine whether body mass index (BMI) influences the risk of low back pain (LBP) in a population exposed to whole body vibration (WBV). For this a self-administered questionnaire was sent to 467 participants, driving occupational vehicles. Vibration measurements were performed according to ISO 2631-1 on a representative sample (n=30) of this population. For each participant, we calculated the current root mean square (r.m.s.) over an 8 h (A(8)) working day. The questionnaire response rate was 47% (n=221). We did not find a significant correlation between BMI and the onset of LBP in the last 7 days (r=0.07, p=0.34) nor for LBP in past 12 months (r=-0.30, p=0.63). No significant increased risk was found for the onset of LBP with the increase of BMI, neither for the last 7 days (OR 1.02; 95% CI: 0.93-1.23) nor for the past 12 months LBP (OR 0.98; 95% CI: 0.89-1.09). Introducing the interaction with WBV exposure in the logistic regression model, did not result a significant increased risk in the onset of LBP-7 days (OR 0.97; 95% CI: 0.92-1.01) nor in the onset of LBP 12 months (OR 0.97; 95% CI: 0.93-1.01) either. Occupational participants exposed to WBV, with a high BMI do not have an increased risk for the development of LBP.

Psychosocial factors and low back pain among college students

OBJECTIVE AND PARTICIPANTS

The authors evaluated psychosocial factors of stress and their effects on the prevalence of low back pain (LBP) among a population of college students in a major university in Colorado.

METHODS

This was a nested cross-sectional study of 973 respondents who completed the National College Health Assessment survey. The authors evaluated a subset of questions pertaining to psychosocial stressors against the presence of LBP.

RESULTS

The annual prevalence of LBP among the population studied was 42.8%. The stressful psychosocial variables of feeling very sad, exhausted, and overwhelmed were associated with the prevalence of LBP.

CONCLUSIONS

The prevalence of LBP among this younger population is significant and understudied.

The role of physical fitness as risk indicator of increased low back pain intensity among people working with physically and mentally disabled persons: a 30-month prospective study

STUDY DESIGN

A prospective cohort study.

OBJECTIVE

To study if low level of physical fitness was associated with increased low back pain (LBP) intensity at 30-month follow-up.

SUMMARY OF BACKGROUND DATA

The evidence of low physical fitness as a risk factor for LBP is inconclusive due to contradictory results.

METHODS

Study participants were 327 employees (women = 271, men = 56) at institutions for physically and mentally disabled persons. Physical fitness was measured by tests of: back extension and flexion endurance, flexibility and balance; and by self-assessed aerobic fitness, muscle strength, endurance, flexibility and balance, using visual analogue scales. Low back pain, lifestyle parameters, and physical and psychosocial work factors were assessed by questionnaires at baseline and at follow-up. Outcome was defined as an increase above 2 steps in average LBP intensity during the previous year (0-10).

RESULTS

Persons with low level back endurance showed an insignificantly higher risk of increased LBP intensity (OR = 2.4, P = 0.076), whereas persons with medium level back endurance were at significantly higher risk (OR = 2.7, P = 0.034) compared with those with high level back endurance. The general association between isometric back extension endurance and increased LBP intensity was insignificant (P = 0.067). Persons with medium level self-assessed aerobic fitness were at lower risk of increased LBP intensity compared with those with high level (OR = 0.37, P = 0.02), although the general association of aerobic fitness was insignificant (0.066). Performance-based back flexion endurance, flexibility, and balance; and self-assessed muscle strength, endurance, flexibility, and balance were not associated with increased LBP intensity.

CONCLUSION

The significant association between medium level back extension endurance and increased LBP intensity supports the finding of other studies that particularly back extension endurance is an important physical fitness component in preventing LBP and that the subcomponents of physical fitness are related in different ways to LBP.

Is a history of work-related low back injury associated with prevalent low back pain and depression in the general population?

Background

Little is known about the role of prior occupational low back injury in future episodes of low back pain and disability in the general population. We conducted a study to determine if a lifetime history of work-related low back injury is associated with prevalent severity-graded low back pain, depressive symptoms, or both, in the general population.

Methods

We used data from the Saskatchewan Health and Back Pain Survey – a population-based cross-sectional survey mailed to a random, stratified sample of 2,184 Saskatchewan adults 20 to 69 years of age in 1995. Information on the main independent variable was gathered by asking respondents whether they had ever injured their low back at work. Our outcomes, the 6-month period prevalence of severity-graded low back pain and depressive symptoms during the past week, were measured with valid and reliable questionnaires. The associations between prior work-related low back injury and our outcomes were estimated through multinomial and binary multivariable logistic regression with adjustment for age, gender, and other important covariates.

Results

Fifty-five percent of the eligible population participated. Of the 1,086 participants who responded to the question about the main independent variable, 38.0% reported a history of work-related low back injury. A history of work-related low back injury was positively associated with low intensity/low disability low back pain (OR, 3.66; 95%CI, 2.48–5.42), with high intensity/low disability low back pain (OR, 4.03; 95%CI, 2.41–6.76), and with high disability low back pain (OR, 6.76; 95%CI, 3.80–12.01). No association was found between a history of work-related low back injury and depression (OR, 0.85; 95%CI, 0.55–1.30).

Conclusion

Our analysis shows an association between past occupational low back injury and increasing severity of prevalent low back pain, but not depression. These results suggest that past work-related low back injury may be an important risk factor for future episodes of low back pain and disability in the general population.

Work status as a predictor of surgical outcome of discogenic low back pain

STUDY DESIGN

Prospective observational study.

OBJECTIVES

To evaluate the role of work status as a predictor of outcome from anterior lumbar fusion.

SUMMARY OF BACKGROUND DATA

Many psychosocial factors have been identified as predictors of chronic disability and of outcomes of surgery. Workers' Compensation and job satisfaction are two of the strongest and most evaluated factors. Work status at the time of intervention may also be relevant but has rarely been studied independently in patients having lumbar fusion.

METHODS

A total of 106 patients with discogenic low back pain were treated by anterior lumbar interbody fusion. Patients were prospectively monitored by VAS, Roland Morris score, and work status. The influence of preoperative work status on outcome variables was assessed using odds ratios. A multivariate analysis was performed to assess influence of other confounding variables. Follow-up was a mean 29.7 months with 95% greater than 1 year.

RESULTS

Patients working at the time of surgery had a 10.5 times greater likelihood of working at follow-up. Overall, only 43% of nonworkers were working at follow-up compared with 90% of patients who were working before surgery. This association was independent of Workers' Compensation, number of levels treated, and other demographic variables. A greater degree of pain relief was seen in patients working before surgery but not in function as measured by the Roland Morris score.

CONCLUSION

These results show that patients with chronic low back pain should be encouraged to continue working up until surgery.

Low back pain and musculoskeletal symptoms among Kansas farmers

BACKGROUND

Farming continues to rank as one of the most dangerous occupations in the United States. The purpose of this study was to determine the prevalence of low back pain and other musculoskeletal disorders (MSDs) among the farmers and to examine the factors associated with occupational back pain. Farmers in a predominately corn and soybean growing region of Kansas served as the study sample.

METHODS

Questionnaires were mailed out to 499 active farmers of a Farmers' Cooperative in Southeast Kansas. The self-administered questionnaire was used to determine the prevalence of self-reported symptoms of back pain and other MSDs and to determine the strength of associations between back pain and work factors.

RESULTS

The participation rate was 57.2%. The low back was the anatomical area with the highest prevalence of self-reported work-related pain (37.5%), followed by the shoulders (25.9%), knees (23.6%), and neck (22.4%). Close to 60% of the farmers reported that they experienced farm work-related MSD symptoms in at least one of the nine body areas in the previous year. Nearly one quarter of the farmers reported seeing a physician for their low back symptoms, and one in five farmers had to modify their work habits due to low back symptoms during the previous year.

CONCLUSIONS

Low back pain and other musculoskeletal conditions are a significant problem for Kansas farmers. This group of Kansas farmers experienced low back pain at a much higher rate than the general working population and higher than other groups of farmers previously studied.

Evaluation of an intervention comprising a no lifting policy in Australian hospitals

The No Lifting Policy has been adopted in Australia to prevent back pain and injuries among nurses. The present study focuses on the intervention of the "No Lift System" (NLS). The purpose of this cross-sectional study was to evaluate the use of transfer equipment, number of injuries, pain/symptoms and absence from work among nurses after the intervention of the NLS (n=201), and compare to nurses at two control hospitals (n=256). A comprehensive questionnaire was used for data collection. The results show that at the hospital where the NLS had been introduced, the nurses used the purchased transfer equipment regularly. They had significantly fewer back injuries, less pain/symptoms and less absence from work due to musculoskeletal pain/symptoms compared with nurses at the control hospitals. The study showed strong evidence for supporting the implementation of the NLS. The positive results shown in the present study can probably be explained by the agreement between the management, the union and the nurses concerning the implementation of the NLS, as well as its comprehensive approach and participatory design.

The role of physical workload and pain related fear in the development of low back pain in young workers: evidence from the BelCoBack Study; results after one year of follow up

AIMS

To study the influence of work related physical and psychosocial factors and individual characteristics on the occurrence of low back pain among young and pain free workers.

METHODS

The Belgian Cohort Back Study was designed as a prospective cohort study. The study population of this paper consisted of 716 young healthcare or distribution workers without low back pain lasting seven or more consecutive days during the year before inclusion. The median age was 26 years with an interquartile range between 24 and 29 years. At baseline, these workers filled in a questionnaire with physical exposures, work related psychosocial factors and individual characteristics. One year later, the occurrence of low back pain lasting seven or more consecutive days and some of its characteristics were registered by means of a questionnaire. To assess the respective role of predictors at baseline on the occurrence of low back pain in the following year, Cox regression with a constant risk period for all subjects was applied.

RESULTS

After one year of follow up, 12.6% (95% CI 10.1 to 15.0) of the 716 workers had developed low back pain lasting seven or more consecutive days. An increased risk was observed for working with the trunk in a bent and twisted position for more than two hours a day (RR 2.2, 95% CI 1.2 to 4.1), inability to change posture regularly (RR 2.1, 95% CI 1.3 to 3.5), back complaints in the year before inclusion (RR 1.7, 95% CI 1.1 to 2.8), and high scores of pain related fear (RR 1.8, 95% CI 1.0 to 3.1). Work related psychosocial factors and physical factors during leisure time were not predictive.

CONCLUSION

This study highlighted the importance of physical work factors and revealed the importance of high scores of pain related fear in the development of low back pain among young workers.

On the evolution of task-based analysis of manual materials handling, and its applicability in contemporary ergonomics

The industrial revolution significantly changed the way work was organized and analyzed by the introduction and widespread implementation of the division of labor philosophy. This philosophy has continued to dominate work design, and has evolved beyond the factory to include many facets of service industries, and even professional occupations. The analysis of manual work, particularly materials handling tasks, remains an active domain of ergonomics research and practice. Many of the task-analytic tools used for workplace analysis are rooted in the philosophy of dividing work into elements, analyzing the individual elements, and synthesizing the results into conclusions about the entire job, including the risk of contracting musculoskeletal disorders (MSDs). The authors discuss the notion that the nature of modern work, which is characterized by multiple tasks in a complex time pattern, and the complex nature of MSDs, which are influenced by biomechanical as well as psychological, political, and economic factors, may limit the effectiveness of classical task analytic techniques in preventing MSDs.

Childhood and early adult predictors of risk of incident back pain: Ontario Child Health Study 2001 follow-up

Musculoskeletal disorders of the back and spine are a leading cause of disability in working-age populations. There is limited information on the potential consequences of childhood socioeconomic and health status on the risk of incident back pain in early adulthood. The authors describe factors associated with having had a first episode of back pain during the past year in the Ontario Child Health Study, a prospective cohort study of children who were aged 4-16 years at the time of enrollment in 1983 and were resurveyed in 2001. Respondents reporting a first episode of back pain (n=143) were compared with respondents who had never experienced back pain (n=896). The annual incidence of a first episode of back pain in this sample of young adults was 74.7/1,000. Following adjustment for age, sex, childhood conditions, childhood health status, and measures of early adult health, behavior, socioeconomic status, and work environment, the risk of incident back pain was associated with both low (odds ratio (OR)=1.86, 95% confidence interval (CI): 1.14, 3.03) and moderate/high (OR=1.85, 95% CI: 1.07, 3.02) levels of psychological distress, current heavy smoking (OR=1.85, 95% CI: 1.10, 3.10), lower levels of parental education in childhood (OR=1.72, 95% CI: 1.06, 2.80), and emotional or behavioral disorders in childhood (OR=1.87, 95% CI: 1.02, 3.41). The associations of low childhood socioeconomic status and childhood emotional and behavioral disorders with risk of incident back pain in early adulthood are important findings with implications for better understanding the etiology of soft-tissue disorders.

Use of complementary and alternative therapies by patients with self-reported chronic back pain: a nationwide survey in Canada

OBJECTIVE

Complementary and alternative medicine (CAM) is gaining popularity among patients with chronic back pain. We looked for factors associated with CAM use.

METHODS

The data came from the cross-sectional household component of the 1996-1997 National Population Health Survey on the health status and behaviors of Canadians. The sample comprising 66.999 individuals aged 20 years or older represented 21 million adults. Cross tabulations were used to estimate the percentage of CAM use among adults with chronic back pain. Factors independently associated with CAM use during the year before the surveys were identified using multiple logistic regression.

RESULTS

CAM use was highest in the subgroup of Canadian adults reporting chronic back pain (39.07%). CAM use was associated with younger age, being married, having a higher level of education, and earning a higher income. Overall, the CAM users reported less pain, greater analgesic use, more depression, and more co-morbidities. In addition to CAM, these patients used conventional medical services.

CONCLUSION

Our results show that patients with chronic back pain who use CAM are more active, more involved in social life, and healthier, suggesting better management of their condition. They use CAM in addition to, rather than instead of, conventional care. CAM use in these patients may be ascribable to dissatisfaction with mainstream physicians.

Risk factors for musculoskeletal symptoms and ensuing health care use and sick leave

STUDY DESIGN

Longitudinal study with a 6-month follow-up.

OBJECTIVE

To investigate whether demographic, work-related physical and psychosocial risk factors involved in the occurrence of musculoskeletal symptoms also determine subsequent health care use and sick leave.

SUMMARY OF BACKGROUND DATA

Preventing the socioeconomic consequences of disability from musculoskeletal symptoms may be a goal separate from that of eliminating the symptoms themselves; thus, other factors may need to be addressed in intervention.

METHODS

A questionnaire provided data on demographics and work-related factors, musculoskeletal symptoms, and ensuing health care use and sick leave among 407 industrial workers.

RESULTS

The 12-month prevalence of low back pain (LBP) and neck/upper extremity symptoms was 52% and 56%, respectively. Of those individuals with symptoms at baseline, 68% had a recurrence of LBP, and 62% a recurrence of neck/upper extremity symptoms during a 6-month follow-up. The recurrence of sick leave for a particular musculoskeletal complaint was approximately 30%, while recurrence of health care use was more than 40%. Recurrence of symptoms, health care use, and sick leave were strongly associated with a history of severe symptoms. Physical load, high job strain, and low social support at work determined the occurrence of LBP, related health care use, and sick leave. Older age and living alone were also important risk factors, especially for sick leave. High job strain determined the occurrence of neck/upper extremity symptoms, related health care use, and sick leave. Being female and living alone increased the probability of the occurrence of all 3 endpoints, especially the occurrence of sick leave.

CONCLUSIONS

Work-related factors that were associated with the occurrence of musculoskeletal symptoms were quite similar to those associated with health care use and sick leave. However, for LBP, older age and living alone, and, for neck/upper extremity symptoms, living alone and being female more strongly determined whether subjects with these complaints took sick leave. These results imply that prevention strategies aimed at minimizing the risks of the occurrence of work-related musculoskeletal symptoms and prevention programs aimed at reducing sick leave may need to emphasize different sets of risk factors.

Study on musculoskeletal disorders in a machinery manufacturing plant

Musculoskeletal disorders and related risk factors in machinery manufacturing were investigated using interviews, postural analysis, and the revised National Institute for Occupational Safety & Health lifting equation. Sixty-nine workers involved in manual materials handling (Job A) and 51 machinery workers less involved with manual material-handling tasks (Job B) were studied. Low back pain (LBP) (at least one episode lasting for 24 hours or more in past 12 months) prevalence rates were 63.8% and 37.3% for Jobs A and B, respectively. Prevalence rates of LBP every day for a week or more attributed to lifting were 26.09% and 5.88% for Jobs A and B, respectively. Multiple regression analysis revealed that lifting repetitiveness and work age contributed to the occurrence of LBP. The "composite load" (object weight x activity repetitiveness) had a significant adverse effect on LBP.

Associations of psychosocial and individual factors with three different categories of back disorder among nursing staff

Although back disorders are a major occupational problem for nursing staff, few studies distinguish different types. By means of a structured questionnaire, we performed a cross-sectional study on the prevalence of diagnosed lumbar disc hernia, chronic low-back pain (LBP) (at least 90 d in the preceding 12 months) and acute LBP (intense pain for at least 1 d) with respect to physical, individual and psychosocial factors among female nurses (n=587), nursing aides (n=228) and head-nurses (n=43) working in a university hospital (95% of the female workforce). Almost all respondents reported known high-risk occupational activities. Overall prevalence of reported back disorders was 44% (acute LBP 19%, chronic LBP 17%, lumbar hernia 8%). On multinomial logistic regression analysis, scoliosis and commonly stress-related psychosomatic symptoms were associated with all three types of back disorder; trauma/fractures of the spine, pelvis and/or legs and a global work-environment/job-satisfaction score with acute LBP; increasing age with lumbar disc hernia. While confirming the relevance of considering different definitions of back disorder, our data indicate items for investigation in cohort studies. These include: identification of specific risk factors for lumbar hernia; avoidance of possible work-environment risk factors such as hurried execution of different tasks at the same time; and influence on job suitability of underlying spinal pathologies such as scoliosis.

Risk factors for work-related low back pain in registered nurses, and potential obstacles in using mechanical lifting devices

Back pain disability is a serious and costly problem affecting the nursing profession. The purposes of this study were to determine risk factors for work-related low back pain (WRLBP) in registered nurses and to record the reported use or reasons for nonuse of mechanical lifts. Our hypothesis was that workers who attributed the cause of WRLBP to their own actions would be knowledgeable about back safety, would be more likely to use lifts, and would report less WRLBP. A random sample of 270 registered nurses was selected from two acute care hospitals in central Illinois to identify WRLBP risk factors. This cross-sectional study gathered information on individual, physical workload, psychological, and organizational factors that may present a risk for WRLBP. Information was also collected on the use of safety devices and back pain symptoms. The response rate was 50.4%. Nearly 84% of respondents had WRLBP in the past, and 36.2% had WRLBP in the past year that limited movement or interfered with routine activities. Among the risk factors significantly associated with WRLBP were more years worked in nursing, frequent lifting, and low social support. Only 11% reported that they routinely used mechanical lifting devices, and the primary reason given for failure to use lifting equipment was unavailability of equipment. The reasons for the lack of use of mechanical lifts should be investigated and addressed.

Risk factors for sickness absence because of low back pain among scaffolders: a 3-year follow-up study

STUDY DESIGN

A prospective cohort study was conducted.

OBJECTIVE

To find risk factors for short-term (<or=14 days) and long-term (>14 days) sickness absence because of low back pain among scaffolders.

SUMMARY OF BACKGROUND DATA

Although some studies have described the relation between work-related risk factors for musculoskeletal disease and sickness absence, little is known about the role of individual, physical, and psychosocial factors and different end points of low back pain as risk factors for sickness absence among scaffolders.

METHODS

Between 1998 and 2001, 222 scaffolders and 66 supervisors (response rate, 86%) completed a questionnaire at baseline. In addition, data on sickness absence were collected from absence records.

RESULTS

At baseline, 60% of the study population had experienced an episode of low back pain in the 12 months preceding the investigation, 37% of which were of chronic nature. During the follow-up period, 34% of the population had been on sick leave for at least one episode of low back pain. The risk factors for sickness absence less than 2 weeks were a high physical load from strenuous arm movements and severe low back pain. Workers with severe low back pain were at higher risk for sickness absence longer than 2 weeks. Psychosocial workload and individual characteristics did not predict the occurrence of sickness absence because of low back pain.

CONCLUSIONS

Because work-related physical load was a risk factor for sickness absence less than 2 weeks and severe low back pain was a risk factor for sickness absence both shorter than and longer than 2 weeks, a focus on secondary prevention for scaffolders with severe low back pain is advised.

Symptoms of musculoskeletal disorders among apprentice construction workers

Musculoskeletal disorders (MSDs) are a major cause of work-related disability and lost-time illnesses for many occupational groups. This study determined the prevalence of musculoskeletal symptoms among young construction workers. A symptom and job factors survey was self-administered to 996 construction apprentices. Prevalence was determined by the percent of positive responses to musculoskeletal symptom questions. Odds ratios and 95 percent confidence intervals were the measures of association between prevalent musculoskeletal symptoms and demographic, leisure, and job factors and were determined by logistic regression. The low back was the site most commonly reported for job-related musculoskeletal symptoms (54.4%), which was also the most common reason for seeking care from a physician (16.8%) and missing work (7.3%). Number of years worked in the construction trade was significantly associated with knee (p-trend = 0.0009) and wrist/hand (p-trend < 0.04) MSD symptoms and was suggestive of an association with low back pain (p-trend = 0.05). "Working in the same position for long periods" was the job factor identified as most problematic, with 49.7 percent of all construction apprentices rating it as a moderate/major problem contributing to musculoskeletal symptoms. Musculoskeletal symptoms are a significant problem among young construction workers at the beginning of their careers. Prevention strategies are needed early in the apprentice training program to reduce the potential disability associated with work-related musculoskeletal symptom disorders.

Lombalgias e trabalho

Lombalgias apresentam altas taxas de prevalência em todos os setores de atividades econômicas sendo que em algumas, a gravidade das alterações levam ao afastamento e à incapacidade ao trabalho. Nos estudos observa-se a necessidade de avaliações e intervenções ergonômicas. Este é um texto de uma revisão das lombalgias e de seus fatores ocupacionais, considerando-se alguns aspectos metodológicos da avaliação da exposição aos fatores de risco; também pontuamos algumas dificuldades atuais, as necessidades e tendências de pesquisas neste tema.

The impact of mental processing and pacing on spine loading: 2002 Volvo Award in biomechanics

STUDY DESIGN

The impact of various levels of mental processing and pacing (during lifting) on spine loading was monitored under laboratory conditions.

OBJECTIVES

To explore how mental demands and pacing influence the biomechanical response and subsequent spine loading and, to determine whether individual characteristics have a modifying role in the responses.

SUMMARY OF BACKGROUND DATA

Modern work often requires rapid physical exertions along with demands of mental processing (both psychosocial stressors). While the effect of physical workplace factors on spine loading has been widely documented, few studies have investigated the impact that interaction of psychosocial factors and individual factors has on spine loads.

METHODS

For this study, 60 subjects lifted boxes while completing two types of mental processing tasks: 1) series tasks with decisions occurring before the act of lifting, and 2) simultaneous tasks with decisions occurring concurrently with the lift. For both of these mental processing conditions, two intensities of mental load were evaluated: simple and complex. Task pacing was also adjusted under slow and fast conditions. Finally, individual characteristics (personality and gender) were evaluated as potential modifiers. An electromyographically assisted model evaluated the three-dimensional spine loads under the experimental conditions.

RESULTS

Simultaneous mental processing had the largest impact on the spine loads, with the complex intensity resulting in increases of 160 N with lateral shear, 80 N with anteroposterior shear, and 700 N with compression. Increased task pace produced greater lateral shear (by 20 N), anteroposterior shear (by 60 N), and compression loads (by 410 N). Gender and personality also influenced loadings by as much as 17%.

CONCLUSIONS

Mental processing stress acted as a catalyst for the biomechanical responses, leading to intensified spine loading. Mental stress appeared to occur as a function of time pressures on task performance and resulted in less controlled movements and increases in trunk muscle coactivation. These adjustments significantly increased spine loading. These results suggest a potential mechanism for the increase in low back pain risk resulting from psychosocial stress caused by modern work demands.

Pushing and pulling in association with low back and shoulder complaints

AIMS

To examine the association between exposure to pushing/pulling at work and low back and shoulder complaints.

METHODS

A cross sectional questionnaire survey was carried out among 434 workers from several companies with mainly pushing/pulling tasks. From the same companies 188 workers without physically demanding tasks served as reference. The questionnaire was used to assess the exposure to pushing/pulling and other physical risk factors for low back and shoulder complaints. Mean scores at company level were used to classify groups into medium and high exposed to pushing/pulling and a reference group. Psychosocial factors at work were also assessed. Several pain related questionnaires were used to assess the 12 month prevalence of low back and shoulder complaints in three dimensions: trouble (ache, pain, discomfort), pain intensity, and disability. Prevalence rate ratios (PRs) were calculated using Cox's proportional hazards regression analysis.

RESULTS

The 12 month prevalence of low back complaints was almost equal for all three groups. The prevalence of shoulder complaints increased with an increase in exposure level. Adjusted PRs showed that the high exposed group had an increased risk for low back complaints compared to the reference group. For all dimensions of shoulder complaints a clear tendency towards a dose-response relation was observed. The high exposed group had significant PRs for shoulder complaints, ranging from 2.09 to 6.37. Generally, psychosocial factors had a confounding effect for pain intensity and disability, but not for trouble.

CONCLUSIONS

For shoulder complaints a dose-response relation was observed for exposure to pushing/pulling. Low back complaints were less consistently associated with pushing/pulling. Stronger associations were observed for more severe cases of low back and shoulder complaints. It is hypothesised that work related psychosocial factors affect these associations.

Risk factors associated with the transition from acute to chronic occupational back pain

STUDY DESIGN

A prospective cohort study was conducted on workers claiming earnings-related compensation for low back pain. Information obtained at the time of the initial claim was linked to compensation status (still claiming or not claiming) 3 months later.

OBJECTIVE

To identify individual, psychosocial, and workplace risk factors associated with the transition from acute to chronic occupational back pain.

SUMMARY OF BACKGROUND DATA

Despite the magnitude of the economic and social costs associated with chronic occupational back pain, few prospective studies have investigated risk factors identifiable in the acute stage.

METHODS

At the time of the initial compensation claim, a self-administered questionnaire was used to gather information on a wide range of risk factors. Then 3 months later, chronicity was determined from claimants' computerized records.

RESULTS

The findings showed that 3 months after the initial assessment, 204 of the recruited 854 claimants (23.9%) still were receiving compensation payments. A combined multiple regression model of individual, psychosocial, and workplace risk factors demonstrated that severe leg pain (odds ratio [OR], 1.9), obesity (OR, 1.7), all three Oswestry Disability Index categories above minimal disability (OR, 3.1-4), a General Health Questionnaire score of at least 6 (OR, 1.9), unavailability of light duties on return to work (OR, 1.7), and a job requirement of lifting for three fourths of the day or more all were significant, independent determinants of chronicity (P < 0.05).

CONCLUSIONS

Simple self-report measures of individual, psychosocial, and workplace factors administered when earnings-related compensation for back pain is claimed initially can identify individuals with increased odds for development of chronic occupational disability.

Spine loading characteristics of patients with low back pain compared with asymptomatic individuals

STUDY DESIGN

Patients with low back pain and asymptomatic individuals were evaluated while performing controlled and free-dynamic lifting tasks in a laboratory setting.

OBJECTIVE

To evaluate how low back pain influences spine loading during lifting tasks.

SUMMARY OF BACKGROUND DATA

An important, yet unresolved, issue associated with low back pain is whether patients with low back pain experience spine loading that differs from that of individuals who are asymptomatic for low back pain. This is important to understand because excessive spine loading is suspected of accelerating disc degeneration in those whose spines are damaged already.

METHODS

In this study, 22 patients with low back pain and 22 asymptomatic individuals performed controlled and free-dynamic exertions. Trunk muscle activity, trunk kinematics, and trunk kinetics were used to evaluate three- dimensional spine loading using an electromyography- assisted model in conjunction with a new electromyographic calibration procedure.

RESULTS

Patients with low back pain experienced 26% greater spine compression and 75% greater lateral shear (normalized to moment) than the asymptomatic group during the controlled exertions. The increased spine loading resulted from muscle coactivation. When permitted to move freely, the patients with low back pain compensated kinematically in an attempt to minimize external moment exposure. Increased muscle coactivation and greater body mass resulted in significantly increased absolute spine loading for the patients with low back pain, especially when lifting from low vertical heights.

CONCLUSIONS

The findings suggest a significant mechanical spine loading cost is associated with low back pain resulting from trunk muscle coactivation. This loading is further exacerbated by the increases in body weight that often accompany low back pain. Patient weight control and proper workplace design can minimize the additional spine loading associated with low back pain.

Risk factors for back pain among male farmers: analysis of Iowa Farm Family Health and Hazard Surveillance Study

BACKGROUND

Back pain causes considerable morbidity, disability, and economic loss among workers. Farmers handle heavy objects, often in awkward postures. However, the prevalence of back pain among farmers and the risk factors associated with back pain are not well known.

METHODS

In this study, we assess the frequency of risk factors for back pain among 287 Iowa male farmers. From 1992 to 1994, using a mail questionnaire, we collected data on potential risk factors for back pain. Eighteen months later, we surveyed occurrence of back pain as the outcome measure.

RESULTS

Thirty-one percent of farmers reported having daily back pain for a week or more during the past 12 months compared to 18.5% in the general working population. Using a multiple logistic regression model, we found two factors associated with back pain: 45-59 years of age (OR = 2.13, 95% CI 1.02-4.43) and having a non-agricultural job as the major occupation (OR = 2.02, 95% CI 0.98-4.17, P = 0.055).

CONCLUSIONS

Farmers had a significantly higher prevalence of back pain than the general working population. Middle-aged farmers and those with additional non-agricultural jobs had the highest risk for back pain.

Predictors of low back pain onset in a prospective British study

OBJECTIVES

This study examined predictors of low back pain onset in a British birth cohort.

METHODS

Univariate and multivariate analyses focused on individuals who experienced onset of low back pain at 32 to 33 years of age (n= 571) and individuals who were pain free (n = 5210). Participants were members of the 1958 British birth cohort.

RESULTS

Incident pain was elevated among those with psychological distress at 23 years of age (adjusted odds ratio [OR] = 2.52, 95% confidence interval [CI] = 1.65, 3.86) and among persistent moderate or heavy smokers (adjusted OR = 1.63, 95% CI = 1.23, 2.17). Significant univariate associations involving other factors (e.g., social class, childhood emotional status, body mass index, job satisfaction) did not persist in multivariate analyses.

CONCLUSIONS

This prospectively studied cohort provides evidence that psychological distress more than doubles later risk of low back pain, with smoking having a modest independent effect. Other prospective studies are needed to confirm these findings before implications for low back pain prevention can be assessed.

Interrelations of risk factors and low back pain in scaffolders

OBJECTIVES

To assess with a cross sectional study the interrelations between physical, psychosocial, and individual risk factors and different end points of low back pain.

METHODS

In total, 229 scaffolders and 59 supervisors completed a questionnaire about manual handling of materials, awkward back posture, strenuous arm position, perceived exertion, psychosocial load, need for recovery, and general health. Physical load at the worksite was also measured with many frequent observations. Interrelations between risk factors and their relation with four end points of low back pain were investigated.

RESULTS

Interrelations were strong among self reported determinants of physical load but showed an inverted trend for both age and total working experience, which could indicate the presence of a healthy worker effect. Weak relations existed between variables of psychosocial and physical load. The multivariate analyses showed a significant relation between high manual handling of materials, moderate perceived general health, high job demands, and low back pain in the past 12 months. Chronic low back pain was significantly correlated with high perceived exertion and moderate perceived general health. Severe low back pain was significantly correlated with awkward back postures, high need for recovery, and high job demands. Finally, low back pain with perceived disability was significantly related to strenuous shoulder positions and moderate perceived general health. All end points of low back pain were consistently associated with physical load whereas psychosocial aspects showed a more diverse pattern.

CONCLUSIONS

The findings of this study suggest that work related risk factors may vary according to different definitions of low back pain. Distinct patterns of risk factors might enhance different expressions of it. Scaffolders are a group at high risk of developing persistent forms of low back pain.

Effect of age on outcomes of tertiary rehabilitation for chronic disabling spinal disorders

STUDY DESIGN

A prospective cohort study evaluating age as a factor in treatment outcomes for chronic disabling work-related spinal disorders undergoing tertiary rehabilitation.

OBJECTIVE

To assess the association between age and objective psychosocioeconomic treatment outcomes for work-related spinal disorders undergoing functional restoration.

SUMMARY OF BACKGROUND DATA

As early as the 1950s, a link between age and low back symptoms has been identified in the literature. Several studies have demonstrated that the occurrence of low back pain is positively correlated with age up to about 50-60 years, after which prevalence declines. It has been argued that this pattern is stronger for more severe, chronic back pain cases. Little research attention has been given to age as a factor in treatment outcomes for work-related spinal disorders.

METHODS

A cohort of 1052 chronically disabled (none working full-time when starting the rehabilitation program) spinal disorder (CDSD) patients were placed into five groups based on age: Group 1, <25 years (22 +/- 2 years, n = 59); Group 2, 25-34 years (30 +/- 3 years, n = 301); Group 3, 35-44 years (39 +/- 3 years, n = 381); Group 4, 45-54 (49 +/- 3 years, n = 237); and Group 5, > or =55 years (59 +/- 4 years, n = 74). All patients completed a functional restoration program combining quantitatively directed exercise progression with a multimodal disability management approach using psychological and case management techniques. Before the start of the program, and again on completion of the program, all patients received a psychosocial evaluation and were also assessed on a variety of physical motion, strength, aerobic, and functional factors, and a cumulative score was calculated, which aggregates and averages these physical measures. A structured clinical interview examining socioeconomic outcomes (work return, health utilization, recurrent injury, and resolution of financial disputes) was conducted at 1 year after program completion, and at least partial information was obtained from this interview on all consecutive patients in the study.

RESULTS

The length of pretreatment disability increased with age (P < 0.001), as well as pretreatment surgery rates (P < 0.002). A Mantel-Haenzel chi2 test for linear trend across age groups revealed that the percentage of patients who returned to work declined progressively from 100% in Group 1 to 69% in Group 5 (P < 0.001). The same linear trend was revealed for the percentage of patients retaining work at the end of 1 year (98-62%, P < 0.001). Older workers returned to the same job and/or the same employer (P < 0.005). Younger workers found different jobs with new employers (48-11%, P < 0.0001). Analysis of variance for the disability questionnaire revealed that after treatment subjective disability progressively increased (while improvements decreased) from Group 1 to Group 5 (P < 0.01). The cumulative physical score variable, even normalized for age, was progressively lower from Group 1 to Group 5, both at pretreatment (P < 0.03) and post-treatment (P < 0.02).

CONCLUSIONS

The present study represents the first large-scale examination of the association between age and treatment outcomes for a work-related CDSD population. Age is significantly and linearly related to pretreatment duration of disability and frequency of pretreatment surgeries. After rehabilitation treatment there is a linear decrement in both work return and work retention, so that younger patients are far more likely to return and hold work after functional restoration. Older workers who go back to work are much more likely to return to the same employer and do the same job, or to become self-employed. Calculation of odds ratios revealed that patients >55 years are 5.68 times more likely to return to the same job and employer, relative to those <25 years; those >55 years were also approximately three times more likely than those <25 years to return to the same employer, compared with those <25 years. Younger workers are far more likely to take a different job and/or seek a new employer. Older patients are also somewhat more likely to seek a new health provider to deal with perceived residual pain/disability. This trend coincides with their higher post-treatment subjective disability levels, and their lower cumulative physical scores both prerehabilitation and postrehabilitation. However, age does not affect additional surgery rates, subsequent injuries, or delays in settling financial disputes.

The association of health risks with workers' compensation costs

The purpose of this study was to investigate the association between health risks and workers' compensation (WC) costs. The 4-year study used Health Risk Appraisal data and focused on 1996-to-1999 WC costs among Xerox Corporation's long-term employees. High WC costs were related to individual health risks, especially Health Age Index (a measure of controllable risks), smoking, poor physical health, physical inactivity, and life dissatisfaction. WC costs increased with increasing health risk status (low-risk to medium-risk to high-risk). Low-risk employees had the lowest costs. In this population, 85% of WC costs could be attributed to excess risks (medium- or high-risk) or non-participation. Among those with claims, a savings of $1238 per person per year was associated with Health Risk Appraisal participation. Addressing WC costs by focusing on employee health status provides an important additional strategy for health promotion programs.