Exposure to physical risk factors in Dutch agriculture: Effect on sick leave due to musculoskeletal disorders

A case-control study examined the association between Dutch farmers' exposure to single physical risk factors or combinations of them and sick leave due to back disorders and neck, shoulder or upper extremity disorders. The sick leave claims of an insurance company in the years 1998-2001 for back (SL-BP, n = 170) and neck, shoulder or upper extremity complaints (SL-EXT, n = 76) were analysed; the controls (n = 721) were insured farmers who had not filed any claim for sick leave in this period. Exposure to physical risk factors was assessed by means of a questionnaire and experts. The questionnaire was used to collect information on the working methods (real or potential way to perform the various work elements within an operation or chain of operations) and the time per year spent on them. A total of 301 working methods were reported. Experts, familiar with the working methods, quantified the exposure to physical risk factors for each working method. Quantification included 'intensity', 'frequency' and 'duration' of exposure. The experts were unknown of the numbers of cases and controls applying each working method. The analysis indicated that sick leave was significantly associated with increased exposure to some single physical risk factors: twisting and whole body vibration with SL-BP and repetitive or static neck postures with SL-EXT. Exposure to medium or high combined physical load, consisting of eight risk factors in SL-BP and 26 risk factors in SL-EXT, showed strong associations with sick leave: Odds Ratios for high exposure varied from 3.3 in the SL-EXT model to 4.3 in the SL-BP model. It is concluded that when developing preventive strategies for the workplace, the effect of exposure to a combination of potential physical risk factors should be seriously considered. Relevance to industry: This paper illustrates the importance of paying attention to exposure to single and combinations of physical risk factors in relation to sick leave due to musculoskeletal disorders in Dutch agriculture. It includes a thorough analysis and estimations of the proportion of sick leave cases that could have been prevented were made. (c) 2005 Elsevier B.V. All rights reserved.