Physical and mental strain at work: Relationships with onset and persistent of multi-site pain in a four-year follow up

Abstract

This study evaluates the association of physical and mental strain with the onset and persistence of multi-site musculoskeletal pain among younger and older employees in four-year follow-up. A questionnaire survey was conducted twice in a food processing company, in 2005 and 2009, with responses from 734 employees (445 younger and 289 older; 65% female). Information on musculoskeletal pain during the preceding week and perceived mental and physical strain was obtained through a structured questionnaire. The association of onset and persistent of multi-site pain with mental and physical strain was estimated with log binomial regression analysis and stratified by age group. Risk ratios (RR) with their 95% confidence intervals (CIs) are reported for the estimates. More than 56% of the employees reported multi-site pain at baseline. Among those who reported multi-site pain at baseline 70% reported persistent multi-site pain and one-third reported new onset of multi-site pain at follow-up. Mental strain at baseline strongly predicted persistence of multi-site pain among both younger and older employees (RR from for younger employees = 1.68, 95% CI = 1.01–2.83 and RR for older employees = 2.25, 95% CI 0 1.27–3.98) but the association with physical strain was not statistically significant. Mental strain predicted the risk of persistence of multi-site pain among both younger and older employees in four-year follow-up but not onset of multi-site pain. Relevance to the industryThe results of this study suggest that monitoring working conditions of all age workers can reduce physical and mental strain, thereby reducing the incidence of multi-site musculoskeletal pain and promoting workers' health.