Dissertation 8.6.2018: Midlife work exposures and musculoskeletal diseases, mobility limitations and disability in old age

MSc (Public Health) Prakash K.C. defends his doctoral dissertation in Occupational Health ”Midlife work exposures and musculoskeletal diseases, mobility limitations and disability in old age: A 28-year follow up of Finnish municipal employees” at the University of Tampere on Friday 8 June. The opponent is Professor Andreas Holtermann (National Research Centre for the Working Environment, Denmark). Professor Clas-Håkan Nygård acts as the custos. The language of the dissertation defence is English.

Strenuous work predicts musculoskeletal diseases in old age

Work-related mental and physical exposures during adulthood may have long-term effects and increase the risk of musculoskeletal diseases (MSDs). These diseases result in mobility decline and subsequent significant physical disability, which reduce adequate functioning in activities of daily living (ADL) and compromise leading an independent life in old age.

Consistent findings worldwide show the detrimental effects of work-related hazards and exposures on the overall health of employees. However, there is limited evidence on the effect of these midlife exposures on health in old age. It is crucial to know these effects from the public health perspective because of the global increase of ageing populations.

The aim of the dissertation was to investigate the associations between work-related exposures in midlife and musculoskeletal diseases, mobility limitations and disabilities in old age through a longitudinal study of Finnish municipal employees followed up for almost three decades. The exposures used were job strain, musculoskeletal biomechanical exposure, shift work and detailed job analysis at midlife. The outcomes were related to musculoskeletal health such as MSDs, mobility limitations (MLs) and disability.

The data from the Finnish Longitudinal Study on Aging Municipal Employees (FLAME) was used in the study. A total of 6,257 (response rate 85%) public sector employees aged 44-58 years from various Finnish municipalities participated in the FLAME study in 1981. They were followed up for the next 28 years at four different time points in 1985 (N=5,556), 1992 (N=4,534), 1997 (N=3,815) and in the year 2009 (N=3,093). The exposures used in this study were from the baseline and the outcomes were mostly from the last follow-up.

The study identified four trajectories of mobility limitations: low persistent, low increasing, high decreasing and high persistent. A job profile in midlife with higher musculoskeletal load strongly predicted the severity of ADL disability in later life in both men and women. Physically less demanding office job profiles among women and technical supervision among men were also high risk groups for the increased severity of disability.

In conclusion, the level of work-related exposures and their interactions in midlife strongly predict musculoskeletal diseases, mobility limitations and disability in old age among both women and men. It is also important to consider the effect of the interaction of two simultaneously occurring work-related exposures while people are still working. The workplace could serve as an arena to prevent and reduce the deterioration of musculoskeletal health in later life. There is still a need for more evidence from intervention studies to establish the causal inference of such associations.

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The dissertation is published in the publication series of Acta Universitatis Tamperensis; 2381, Tampere University Press, Tampere 2018. The dissertation is also published in the e-series Acta Electronica Universitatis Tamperensis; 1890, Tampere University Press 2018.

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