On causes of neck and shoulder pain in the general population

Abstract: The aim of this thesis was to identify risk factors for neck/shoulder pain and disorders. In accordance with the bio-psychosocial perspective used, both physical and psychosocial factors were studied at work as well as during leisure-time. Potential interactive effects of these factors on neck/shoulder pain and the impact of different lengths of exposure prior to the onset of pain and disorders were also studied. Methodological aspects regarding assessment of physical working conditions and regarding retrospectively collected self-reports of musculoskeletal diseases and disorders have been examined. The present thesis is based on three separate projects: the REBUS-study, the MUSIC-Norrtälje study and an evaluation of a changed production process at an automobile plant in Sweden. The REBUS and MUSIC study groups were based on the general population. Repetitive work with the hands, both during work and leisure-time, was revealed to be the factor most constantly associated with incidence of neck/ shoulder pain and disorders. Plausibly a causal relationship exists, which is mainly evident among women. Combinations of factors seem to be of high relevance for the occurrence of upper limb disorders and pain. Deterioration, especially regarding psychosocial factors, contributed more to the incidence of neck/shoulder pain than prevailing demanding psychosocial and physical conditions. A high perceived workload was constantly associated with the incidence of neck/shoulder pain and disorders. When subjects perceive the physical exertion, aspects such as authority over work and length of work cycles seem to be of greater importance than awkward working positions, and distribution of work over the day. The result also indicates considerable impact from earlier episodes of neck/shoulder disorders on new episodes of neck/shoulder pain. Self-reports regarding visits to caregivers and sick leave were found to be reliable and valid for use as outcome data in epidemiological research. Subjects were able to adequately estimate changes in physical working conditions. Considering the results in this thesis, future studies should include both physical and psychosocial conditions from work and leisure-time, as well as organisational working conditions. Interactive effects and the impact of changing working conditions should be included in the analyses, made separately for men and women if possible. Questionnaire-based data provide usable information if the questions are formulated carefully.