OBJECTIVE: The purpose of this study was to develop alternative Strain Index risk classification categories. BACKGROUND: Strain Index scores are usually categorized into four Strain Index "risk categories." The "original" risk categories were developed in the meat-packing industry and may not be fully applicable to other industries. METHOD: Daily Strain Index scores were estimated among 276 manufacturing workers participating in a cohort study of occupational risk factors for hand-arm musculoskeletal symptoms. Each score was categorized using the original method and a new method based on quartiles of Strain Index score values among symptomatic participants. Models examining associations between original Strain Index risk categories and incident hand-arm symptoms were compared to models examining associations between the alternative Strain Index risk categories and incident hand-arm symptoms. RESULTS: Compared to the respective referent categories, a twofold or greater increase in the risk of incident hand-arm symptoms was observed for the highest original Strain Index risk category (HR = 2.06, 95% CI = [1.08-3.92]) and for the second highest alternate Strain Index risk exposure category (HR = 2.21, 95% CI = [1.26-3.85]). Although significant associations between Strain Index risk category and incident hand-arm symptoms were observed for both Strain Index categorization methods, model fit statistics favored the alternate approach. CONCLUSION: Results from this study suggests that the Strain Index risk category structure may need to be tailored to specific populations. APPLICATION: If verified, results from this study provide a better way to identify hazardous manufacturing jobs and target them for exposure reduction.
OBJECTIVE: The purpose of this study was to develop alternative Strain Index risk classification categories. BACKGROUND: Strain Index scores are usually categorized into four Strain Index "risk categories." The "original" risk categories were developed in the meat-packing industry and may not be fully applicable to other industries. METHOD: Daily Strain Index scores were estimated among 276 manufacturing workers participating in a cohort study of occupational risk factors for hand-arm musculoskeletal symptoms. Each score was categorized using the original method and a new method based on quartiles of Strain Index score values among symptomatic participants. Models examining associations between original Strain Index risk categories and incident hand-arm symptoms were compared to models examining associations between the alternative Strain Index risk categories and incident hand-arm symptoms. RESULTS: Compared to the respective referent categories, a twofold or greater increase in the risk of incident hand-arm symptoms was observed for the highest original Strain Index risk category (HR = 2.06, 95% CI = [1.08-3.92]) and for the second highest alternate Strain Index risk exposure category (HR = 2.21, 95% CI = [1.26-3.85]). Although significant associations between Strain Index risk category and incident hand-arm symptoms were observed for both Strain Index categorization methods, model fit statistics favored the alternate approach. CONCLUSION: Results from this study suggests that the Strain Index risk category structure may need to be tailored to specific populations. APPLICATION: If verified, results from this study provide a better way to identify hazardous manufacturing jobs and target them for exposure reduction.
Authors: Phillip Drinkaus; Richard Sesek; Donald Bloswick; Tom Bernard; Bob Walton; Brad Joseph; Gordon Reeve; Joyce Hall Counts Journal: Work Date: 2003
Authors: Fredric Gerr; Nathan B Fethke; Linda Merlino; Dan Anton; John Rosecrance; Michael P Jones; Michele Marcus; Alysha R Meyers Journal: Hum Factors Date: 2014-02 Impact factor: 2.888