Wilhelmina E. Hoogendoorn

Systematic review of psychosocial factors at work and private life as risk factors for back pain

Study Design. A systematic review of observational studies. Objectives. To assess whether psychosocial factors at work and in private life are risk factors for the occurrence of back pain. Summary of Background Data. Several reviews on risk factors for back pain have paid attention to psychosocial factors. However, in none of the published reviews was a strict systematic approach used to identify and summarize the available evidence. Methods. A computerized bibliographical search of several databases was performed, restricted to studies with a cohort or case–control design. A rating system was used to assess the strength of the evidence for various factors, based on the methodologic quality of the studies and the consistency of the findings. Results. Eleven cohort and two case–control studies were included in this review. Strong evidence was found for low social support in the workplace and low job satisfaction as risk factors for back pain. Insufficient evidence was found for an effect of a high work pace, high qualitative demands, low job content, low job control, and psychosocial factors in private life. Conclusions. Evidence was found for an effect of low workplace social support and low job satisfaction. However, the result for workplace social support was sensitive to slight changes in the rating system, and the effect found for low job satisfaction may be a result of insufficient adjustment for psychosocial work characteristics and physical load at work. In addition, the combined evaluation of job content and job control, both aspects of decision latitude, led to strong evidence of a role for low job decision latitude. Thus, based on this review, there is evidence for an effect of work-related psychosocial factors, but the evidence for the role of specific factors has not been established yet.

Flexion and rotation of the trunk and lifting at work are risk factors for low back pain: results of a prospective cohort study.

Study Design. A 3-year prospective cohort study among workers of 34 companies in the Netherlands. Objectives. To investigate the relation between flexion and rotation of the trunk and lifting at work and the occurrence of low back pain. Summary of Background Data. Previous studies on work-related physical risk factors for low back pain either lacked quantification of the physical load or did not take confounding by individual and psychosocial factors into account. Methods. The study population consisted of 861 workers with no low back pain at baseline and complete data on the occurrence of low back pain during the 3-year follow-up period. Physical load at work was assessed by means of analyses of video-recordings. Information on other risk factors and the occurrence of low back pain was obtained by means of self-administered questionnaires. Results. An increased risk of low back pain was observed for workers who worked with the trunk in a minimum of 60° of flexion for more than 5% of the working time (RR 1.5, 95% CI 1.0–2.1), for workers who worked with the trunk in a minimum of 30° of rotation for more than 10% of the working time (RR 1.3, 95% CI 0.9–1.9), and for workers who lifted a load of at least 25 kg more than 15 times per working day (RR 1.6, 95% CI 1.1–2.3). Conclusions. Flexion and rotation of the trunk and lifting at work are moderate risk factors for low back pain, especially at greater levels of exposure.

High physical work load and low job satisfaction increase the risk of sickness absence due to low back pain: Results of a prospective cohort study

Objective: To determine whether physical and psychosocial load at work influence sickness absence due to low back pain. Methods: The research was a part of the study on musculoskeletal disorders, absenteeism, stress, and health (SMASH), a 3 year prospective cohort study on risk factors for musculoskeletal disorders. Workers from 21 companies located throughout The Netherlands participated in the part of this study on sickness absence due to low back pain. The study population consisted of 732 workers with no sickness absences of 3 days or longer due to low back pain in the 3 months before the baseline survey and complete data on the reasons for absences during the follow up period. The mean (range) period of follow up in this group was 37 (7–44) months. Physical load at work was assessed by analyses of video recordings. Baseline information on psychosocial work characteristics was obtained by a questionnaire. Data on sickness absence were collected from company records. The main outcome measure was the rate of sickness absences of 3 days or longer due to low back pain during the follow up period. Results: After adjustment of the work related physical and psychosocial factors for each other and for other potential determinants, significant rate ratios ranging from 2.0 to 3.2 were found for trunk flexion, trunk rotation, lifting, and low job satisfaction. A dose-response relation was found for trunk flexion, but not for trunk rotation or lifting. Non-significant rate ratios of about 1.4 were found for low supervisor support and low coworker support. Quantitative job demands, conflicting demands, decision authority, and skill discretion showed no relation with sickness absence due to low back pain. Conclusions: Flexion and rotation of the trunk, lifting, and low job satisfaction are risk factors for sickness absence due to low back pain. Some indications of a relation between low social support, either from supervisors or coworkers, and sickness absence due to low back pain are also present.

Are neck flexion, neck rotation, and sitting at work risk factors for neck pain? Results of a prospective cohort study

OBJECTIVE To study the relation between neck pain and work related neck flexion, neck rotation, and sitting. METHODS A prospective cohort study was performed with a follow up of 3 years among 1334 workers from 34 companies. Work related physical load was assessed by analysing objectively measured exposure data (video recordings) of neck flexion, neck rotation, and sitting posture. Neck pain was assessed by a questionnaire. Adjustments were made for various physical factors that were related or not related to work, psychosocial factors, and individual characteristics. RESULTS A significant positive relation was found between the percentage of the working time in a sitting position and neck pain, implying an increased risk of neck pain for workers who were sitting for more than 95% of the working time (crude relative risk (RR) 2.01, 95% confidence interval (95% CI) 1.04 to 3.88; adjusted RR 2.34, 95% CI 1.05 to 5.21). A trend for a positive relation between neck flexion and neck pain was found, suggesting an increased risk of neck pain for people working with the neck at a minimum of 20° of flexion for more than 70% of the working time (crude RR 2.01, 95% CI 0.98 to 4.11; adjusted RR 1.63, 95% CI 0.70 to 3.82). No clear relation was found between neck rotation and neck pain. CONCLUSION Sitting at work for more than 95% of the working time seems to be a risk factor for neck pain and there is a trend for a positive relation between neck flexion and neck pain. No clear relation was found between neck rotation and neck pain.

High Quantitative Job Demands and Low Coworker Support As Risk Factors for Neck Pain : Results of a Prospective Cohort Study

Study Design. A 3-year prospective cohort study among 1334 workers was conducted. Objective. To determine whether the work-related psychosocial factors of quantitative job demands, conflicting job demands, skill discretion, decision authority, supervisor support, coworker support, and job security are risk factors for neck pain. Summary of Background Data. Among the various risk factors for neck pain, work-related psychosocial factors play a major role. Previous studies on risk factors for neck pain often had a cross-sectional design, and did not take both physical and psychosocial factors into account. Methods. At baseline, data on work-related psychosocial factors were collected by means of a questionnaire. During the 3-year follow-up period, data on the occurrence of neck pain were collected by means of postal questionnaires. Individuals without neck pain at baseline were selected for the analyses. Cox regression analysis was applied to examine the relation between the work-related psychosocial factors and the cumulative incidence of neck pain. Adjustments were made for various physical factors and individual characteristics. Results. The analysis included 977 patients. Altogether, 141 workers (14.4%) reported that they had experienced neck pain at least once during the 3-year follow-up period. The relation of neck pain to high quantitative job demands (relative risk [RR], 2.14; 95% confidence interval [CI], 1.28–3.58) and low coworker support (RR, 2.43; 95% CI, 1.11–5.29) was statistically significant. An increased risk was found for low decision authority in relation to neck pain (RR, 1.60; 95% CI, 0.74–3.45), but this relation was not statistically significant. Conclusions. High quantitative job demands and low coworker support are independent risk factors for neck pain. There are indications that another risk factor for neck pain is low decision authority.

Comparison of two different approaches for the analysis of data from a prospective cohort study: An application to work related risk factors for low back pain

Aims: To compare the results of a traditional approach using standard regression for the analysis of data from a prospective cohort study with the results of generalised estimating equations (GEE) analysis. Methods: The research was part of a three year prospective cohort study on work related risk factors for low back pain. The study population consisted of a cohort of 1192 workers with no low back pain at baseline. Information on work related physical and psychosocial factors and the occurrence of low back pain was obtained by means of questionnaires at baseline and at the three annual follow up measurements. In a traditional standard logistic regression model, physical and psychosocial risk factors at baseline were related to the cumulative incidence of low back pain during the three year follow up period. In a GEE logistic model, repeated measurements of the physical and psychosocial risk factors were related to low back pain reported at one measurement point later. Results: The traditional standard regression model showed a significant effect of flexion and/or rotation of the upper part of the body (OR = 1.8; 95% CI: 1.2 to 3.0), but not of moving heavy loads (OR = 1.4; 95% CI: 0.7 to 3.1). The GEE model showed a significant effect of both flexion and/or rotation of the upper part of the body (OR = 2.2; 95% CI: 1.5 to 3.3) and moving heavy loads (OR = 1.5; 95% CI: 1.0 to 2.4). No significant associations with low back pain were found for the psychosocial work characteristics with either method, but the GEE model showed weaker odds ratios for these variables than the traditional standard regression model. Conclusions: Results show that there are differences between the two analytical approaches in both the magnitude and the precision of the observed odds ratios.

Generalised estimating equations and low back pain. Authors' reply

We read with interest the article by Hoogendoorn et al who examined the use of different approaches to analysing data from their prospective cohort study of work related exposures and the future onset of low back pain.1 Exposures and outcomes are time dependent factors as they are subject to change over time. The strength of the relation depends on the assumptions of time dependence (or independence) of exposures and outcomes. The effects of these assumptions can be investigated by adopting different modelling approaches to studies that have collected repeated measures of exposure and outcome data over time. Hoogendoorn et al have adopted such an approach in their study of work related risk factors for low back pain.1 Information on work related physical and psychosocial factors and low back pain outcome was collected at baseline and in three annual follow ups. They showed an increased risk of low back pain for work related mechanical factors, when using two different generalised estimating equation (GEE) models compared to the standard logistic regression approach.1 Conversely, for work related psychosocial factors the association with low back pain was weaker when the GEE method was employed. Such an approach is enlightening and we agree that it is important to explore such analytical techniques in the investigation of work related risk factors and musculoskeletal symptoms. Therefore further exploitation of this method of analysis seems appropriate. We have recently conducted a …

Generalised estimating equations and low back pain - Reply

We read with interest the article by Hoogendoorn et al who examined the use of different approaches to analysing data from their prospective cohort study of work related exposures and the future onset of low back pain.1 Exposures and outcomes are time dependent factors as they are subject to change over time. The strength of the relation depends on the assumptions of time dependence (or independence) of exposures and outcomes. The effects of these assumptions can be investigated by adopting different modelling approaches to studies that have collected repeated measures of exposure and outcome data over time. Hoogendoorn et al have adopted such an approach in their study of work related risk factors for low back pain.1 Information on work related physical and psychosocial factors and low back pain outcome was collected at baseline and in three annual follow ups. They showed an increased risk of low back pain for work related mechanical factors, when using two different generalised estimating equation (GEE) models compared to the standard logistic regression approach.1 Conversely, for work related psychosocial factors the association with low back pain was weaker when the GEE method was employed. Such an approach is enlightening and we agree that it is important to explore such analytical techniques in the investigation of work related risk factors and musculoskeletal symptoms. Therefore further exploitation of this method of analysis seems appropriate. We have recently conducted a …