Graduation Year

2020

Document Type

Thesis

Degree

M.S.P.H.

Degree Name

MS in Public Health (M.S.P.H.)

Degree Granting Department

Public Health

Major Professor

Thomas E. Bernard, Ph.D., CIH

Committee Member

Steven Mlynarek, Ph.D., CIH

Committee Member

John Smyth, Ph.D., CIH

Keywords

automotive manufacturing, hand activity, RULA, strain index

Abstract

Distal upper extremity (DUE) musculoskeletal disorders (MSDs) affect thousands of workers annually. Job tasks can have a significant amount of MSD risk depending on the presence of certain risk factors The UAW-Ford Ergonomic Surveillance Tool (EST) is a method specifically designed for the UAW and Ford Motor Company to assess MSD risk in its facilities. The purpose of this report is to evaluate which risk factors in the UAW-Ford EST predict the risk of developing DUE MSDs. Data collected by a previous study on four UAW-Ford automotive manufacturing plants were analyzed. Target jobs were selected based on associated First Time Occupational Visit (FTOV) to the plant clinic or a red flag by the EST. About 50 interviews at each plant were conducted to determine if operators experienced pain or discomfort and if treatment was sought outside of the plant. Risk factors were tested as dichotomous variables representing low and high exposure groups, or the presence or absence of a risk factor and applying logistic regression using the data from the EST.

The presence of impulse loading (p <0.01) had a sensitivity of 0.49 and a specificity of 1.00. Marked hand posture (p =0.02) had a sensitivity of 1.0 and a specificity of 0.09. High repetition (p =0.13) had a sensitivity of 0.89 and a specificity of 0.48. Presence of vibration (p =0.78) had a sensitivity of 0.43 and a specificity of 0.72. The combination of hand posture and repetition represented by an estimated Peak Force Index (PFITLV) (p <0.01) had a sensitivity of 0.88 and a specificity of 0.48. When impulse loading and hand posture were modeled together in a logistic regression, they had good ability to discriminate between cases and non-cases (AUC =0.84). This remained true when PFITLV and impulse were modeled together (AUC =0.85). This analysis indicates that impulse loading in manufacturing jobs and poor hand postures are associated with DUE MSDs.

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