Attributions, Stress, and Work-Related Low Back Pain George Byrns, MPH, Ph.D., CIH Illinois State University

Background & Significance n LBP WC claims in the US (1992) – 16% of claims – 33% of costs (>$49 billion) n Risk factors – individual, job-related, physical, & psychosocial n In spite of mechanization, LBP is still a major source of disability

Exposure DoseResponse Capacity Physical Stain Model

Conceptual Model for Attributions as a Risk Factor for LBP Attributions Resources Psychological demand Psychological Stress Knowledge of Back Safety Low Back Pain Function Injury WorkEnvIronmentWorkEnvIronment Physical demand

The Dimensions of Resources ResourcesResources Individual characteristics Social environment Safety climate Age Gender Fitness Body mass index Education Coping skills Smoking Prior LBP Job social support Home social support Management support Implementation

What is an attribution? n Attribution: a natural human tendency to see patterns or explain unfortunate events n Attributions have 3 major dimensions: – locus of causation – stability/permanence – controllability

How are attributions & stress related? n External, permanent, uncontrollable factors are expected to cause stress n Attributions of LBP cause may affect: – the worker’s knowledge of back safety – perceived job control – likelihood of reporting LBP

How is stress related to LBP? n Prolonged muscle tension may – overload muscle fibers – result in loss of blood flow to muscles n Overload documented in neck & shoulders – Also likely in low back n There may be other mechanisms as well

Hypotheses H1: Persons knowledgeable in back safety will attribute internal causes of LBP (behavior) H2: Less LBP in those high in back safety knowledge. H3: Perceived job control will be higher in those who attribute internal causes of LBP

Hypotheses H4: Workers with LBP will also report high demands, low control & low social support. H5:Workers with LBP are more likely to attribute the cause to an external source.

Specific Aims 1. Measure the prevalence of LBP in garment workers. 2. To observe & record postures & movements of workers performing primary job tasks. 3. Measure worker stress using the Karasek Demand-Control-Support model.

Specific Aims (cont) 4. Measure workers’ attributions of LBP causation. 5. Use attribution theory in a new model to explore the associations between worker stress & LBP.

Research Design & Methods n Study design: cross-sectional n Study population: a garment factory with approximately 400, mostly white, unionized, middle-aged women, & paid by piece work n Data collection: self-administered questionnaire & direct observation

Research Design & Methods (cont) n Developed questionnaire & observation checklist n Developed new scales to measure attributions & knowledge of back safety

Data analysis n Analysis of newly developed scales n Univariate analyses n Bivariate analyses n Multivariate analyses

Results: Reliability & Validity n Karasek’s Demand-Control-Support Model n Newly developed scales n Observation results n Comparison of attributions of managers/supervisors & workers

Comparison of Workers & Managers n Workers (79%) & managers (100%) attribute LBP to worker actions – 86% of workers & 31% of managers also blamed work conditions n When asked which was most important – 56% of workers said work conditions compared to only 6% of managers

Results: LBP Prevalence n Any report of LBP last year: 63.7% n LBP not due to sports or non-occ. causes that limited movement or interfered with work at home or on the job: 36.2%

Knowledge of Back Safety n Knowledgeable workers had high internal attribution (OR = 4.6) p < n Knowledgeable workers do not report less LBP

Perceived Job Control n Higher control in workers with internal attribution & job social support from the supervisor n Also age & income effects

Demand-Control-Support Model n LBP was only associated with high job demand (OR = 2.5, p < 0.01) n LBP was also associated with higher income (OR = 2.4, p < 0.01)

Attributions & LBP n More LBP in workers attributing LBP to job tasks (OR = 4.4, p < 0.001) n Less LBP in workers with high supervisor social support (OR = 0.25, p < 0.01) n Also age & income effects

Limitations n Cross-sectional design – temporality, survivor bias n Recall bias n Inter-rater agreement n Unique study population n Unmeasured variables

Discussion - Implications 1 n Measure attributions before teaching back safety n Improve worker control – attributional retraining – increasing social support

Discussion - Implications 2 n Demand-Control-Support model may need modification for use with LBP n Attribution model works well for study of LBP

Discussion - Future Research n Examine manager/supervisors & worker attributions for presence of mismatch n Use model in other occ. groups & other outcomes n Measure attributions at baseline & do a longitudinal study

Implications of attribution on stress, biomechanics, & LBP n If root cause of LBP is worker actions, need improvements in risk communication n If LBP is caused or contributed by work conditions, need env. modification

Epilogue: Expectancies: Cause & Responsibility Ê Worker is careless-> make worker careful Ë Job is dangerous -> make worker careful Ì Job is dangerous -> make the job safer Í Worker is careless -> make the job safer

Causes of LBP n 90% due to mechanical causes – overuse (spasm) – trauma – deformity (herniated disc) n 10% due to systematic causes – cancer – infection – other disease (ankylosing spondylitis)

Types of LBP n Acute (3-4 mos. duration) – 80-90% spontaneously recover n Chronic (>4 mos. duration) – osteoarthritis, loss of disc flexibility – other age effects: osteoporosis & spinal stenosis

Power: 2 controls per case,  =.05, 1-  =.80 Prevalence =.36 p1=0.70 p2=0.53  =.17 cases = 100 controls = 178 total = 278 (z  /2 + z  ) 2 x (K+1)/K x pq 22 n =

Significant Relationships