Biomechanical and psychosocial risks for low back pain.
Marras-WS; Heaney-CA; Allread-WG; Burr-D; Ferguson-SA; Fujishiro-K; Ashida-S
Atlanta GA; U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, R01-OH-003914, 2007 Jan; :1-138
Low back pain is a common and costly occupational health concern. There are a multitude of risk factors for occupational low back pain including the physical demands of the job, psychosocial characteristics of work, and personal factors. There is a void in the literature examining all three risk factor categories rigorously. Thus, the goal of this project was to examine the physical, psychosocial and personal risk factors that may contribute to occupational low back pain. Methods: A six-month prospective study was conducted in 9 furniture distribution centers. Sixteen psychosocial risk factors were examined through a self-administered questionnaire. The physical demands of the job were evaluated by a certified professional ergonomist. The ergonomist used the American Industrial Hygiene Association Threshold Limit Value lifting guide to evaluate the jobs. Low back pain was measured using two self-report symptom measures and one objective functional performance measure. Employee evaluations were performed at baseline and six-month follow-up visits. The ergonomic evaluation was performed at baseline. Results: Three hundred and nine (309) of the initial 471 workers recruited completed the six-month follow-up. There were weak or insignificant correlations among the three outcome measures of low back pain. Correlation analysis showed that a greater number of psychosocial variables were associated with symptoms compared to biomechanical factors. The objective functional performance measure was correlated with a greater number physical demand measures compared to psychosocial variables. The regression analysis of change in objective functional performance illustrated the interaction of the physical and psychosocial demands. In the low physical demand jobs a high job satisfaction score (psychosocial measure) was protective of objective low back function. In the high physical demand jobs low back function deteriorated regardless of the job satisfaction scores. Classification and regression tree analysis as well as logistic regression, were used to examine categories of workers whose low back function "got worse" or "did not get worse" during the study. Psychosocial and personal factor models were developed for low, medium and high physical demands. The most significant psychosocial factor to the model was role conflict for low physical demands, job satisfaction for medium physical demand and unfairness from the boss for high physical demands. Logistic regression models were also constructed for the two pain symptom outcome measures using three categories of 1) stayed the same, 2) moderate symptoms and 3) stayed highly symptomatic. The knuckle to shoulder number of exertions above the threshold limit value was the major physical demands component and role conflict was the most important psychosocial predictor. Discussion: The low correlations among the three outcome measures suggest that different aspects of low back disorders are being tapped by the different measures. The role of psychosocial measures appears to be greater in pain symptoms measures whereas the role of physical demands appears to be greater in objective functional performance. There is also an interaction between physical demands and psychosocial measures, where in low physical demands situations a high job satisfaction score will be protective of low back function. Conclusions: The three outcome measures were very different indicators of low back pain. The symptoms outcome measures were influenced more by psychosocial risk factors whereas objective functional performance was influenced more by biomechanical risk factors. The interaction between physical demands and psychosocial factor is complex and dependent upon the outcome measures.
Back-injuries; Risk-factors; Occupational-accidents; Occupational-hazards; Musculoskeletal-system-disorders; Musculoskeletal-system; Muscles; Muscle-tension; Muscle-stress; Physiological-factors; Physiological-function; Physiological-stress; Ergonomics; Biomechanics; Biodynamics
William S. Marras, The Ohio State University Institute for Ergonomics, Biodynamics Laboratory ,1971 Neil Avenue Columbus, OH 43210
Final Grant Report
NTIS Accession No.
Disease and Injury: Musculoskeletal Disorders of the Upper Extremities
National Institute for Occupational Safety and Health
Ohio State University