Exposure-Response Relationships for Low Back Pain from Pooled Data

University Of Wisconsin Milwaukee, Milwaukee WI

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Abstract

? DESCRIPTION (provided by applicant): The proposed research offers a unique opportunity to quantify exposure-response relationships between measured occupational biomechanical stressors and prevalence and incidence of three low back pain (LBP) outcomes while adjusting for demographics, LBP history, and psychosocial factors. The three LBP outcomes are: (i) LBP, (ii) Seeking Care for LBP (SC-LBP), and (iii) LBP resulting in lost time (LT-LBP). This study will pool previously collected, raw data from three independently conducted prospective cohort studies. Combined, these studies enrolled workers from 47 US workplaces, representing a wide range of occupations, industries, and physical exposure levels. A total of 1,855 employees were enrolled and 1,275 were followed for up to 54 months (1,903 person-years of follow-up data). Compatible, comprehensive data are available on each worker (i.e., exposure to biomechanical stressors, relevant covariates, and LBP outcomes). Measures of biomechanical stressors used in this study include the: (i) Lifting Index (LI), and (ii) Composite Lifting Index (CLI) from the Revised NIOSH Lifting Equation, and (iii) a newly proposed Cumulative Lifting Index (CULI) that accounts for job rotation and quantifies integrated biomechanical stressors to a worker over an entire work-shift using an innovative, incremental approach. Our comprehensive physical exposure data feature: (i) quantified physical exposure to individual workers measured at baseline, (ii) quantified changes in exposures over time, and (iii) detailed data for each combination of weight lifted/lowered, repetition, horizontal and vertical locations of hands, trave distance, type of grasp and trunk posture (i.e., sub-task data). These pooled data will have more robust distributions and statistical power to: (i) estimate exposure-response relationships between biomechanical stressors (LI, CLI, CULI) and LBP outcomes (LBP, SC-LBP and LT-LBP), (ii) recommend safe exposure limits, and (iii) identify important covariates. Pooling existing data from these three studies will enable us to estimate magnitudes and shapes of relative risks as continuous functions across a wide range of biomechanical stressors: (i) with improved confidence and precision, (ii) for workers with job rotation, and (iii) for tasks with varied combinations of physical exposure risk factors, such as: weight lifted//lowered, repetition, and horizontal and vertical locations of hands. Results from this proposed research will help employers to design safe and productive jobs and provide public-health agencies and occupational health and safety professionals with information to more effectively guide workplace injury prevention programs. Among others, this study addresses the NORA Manufacturing, Services, and Warehousing Sectors and the Exposure Assessments, Musculoskeletal and Authoritative Recommendations Cross-Sectors.