Long-term sickness absence from combined factors related to physical work demands: prospective cohort study

Abstract

Background: The working environment plays an important role in public health. This study investigates the risk for long-term sickness absence (LTSA) from the combination of factors related to physical work demands.

Methods: Employees (n = 22 740) of the general population (the Danish Work Environment & Health study 2012) were followed for two years in the Danish Register for Evaluation of Marginalisation. Using Cox regression analyses we determined the risk of LTSA from four factors; (i) physical work demands, (ii) physical exertion during work, (iii) fatigue after work and (iv) work-limiting pain.

Results: During follow-up 10.2% experienced LTSA. Each of the four factors increased the risk of LTSA with hazard ratios (HR) ranging from 1.30 to 1.57. Scoring high on one (30.3% of the respondents), two (24.4%), three (19.9%) and all four factors (9.2%) gradually increased the risk of LTSA (HR's of 1.39 [95% CI 1.16-1.66], 1.66 [95% CI 1.39-1.99], 1.90 [95% CI 1.57-2.29] and 3.02 [95% CI 2.47-3.68], respectively). Risk estimates remained robust in stratified analyses of age, sex and socioeconomic position. Population attributable fractions were high across all subgroups; 39% (general population), 36% (younger workers), 45% (older workers), 36% (men), 41% (women), 30% (higher socioeconomic position) and 45% (lower socioeconomic position).

Conclusion: The risk of LTSA gradually increased with number of factors related to high physical work demands, underlining the importance of targeting combined factors in risk assessment and preventive interventions.

Figure 1

Conceptual model. In the causal chain to long-term health consequences, high physical work demands increase perceived physical exertion during work, leading to higher levels of fatigue after work and consequently work-limiting pain. However, work-limiting pain can also intensity the perception of physical exertion and fatigue, and may also lead to work-modifications of less demanding tasks. Thus, when studying complex phenomena like labour market attachment, combining inter-dependent factors to investigate the risk for long-term health consequences is a more realistic scenario

Figure 2

Survival plot. X-axis is the time from baseline and y-axis is the survival probability based on the final model (Model 2) using direct adjusted survivor functions. The lines represent from above to below 0 of 4, 1 of 4, 2 of 4, 3 of 4 and 4 of 4 factors (high physical work demands, physical exertion during work, fatigue after work and work-limiting pain), respectively