Exposure assessment : : Gender and context, and target groups for prevention of neck/shoulder and low back pain

Sammanfattning: Neck/shoulder and low back pain are the most frequent sources of pain complaints, health care utilization, and lost work time. The etiology is multifactorial, and includes physical and psychosocial working conditions, outside work conditions, and psychological factors. The sizable number of females and males suffering from neck/shoulder and low back pain underscores the societal importance of the problem, emphasizing that there is urgent need for effective strategies to address it. The main aim of this thesis is to broaden the understanding of gender and context in both the assessment of physical load exposure and the identification of target groups of prevention of neck/shoulder and low back pain. This thesis is based on the MOA Study and the MUSIC-Norrtälje Study. In Paper I, the reproducibility and the validity of eight physical load questions in a public health questionnaire were evaluated by the test-retest method and by a structured personal interview (n=203). Paper II investigated if and how exposure to awkward work postures is associated with occupational gender segregation. Direct measurements of sitting, arm and trunk postures were taken with two different technical instruments on 78 matched pairs of one female and one male worker over one full workday in diverse labor markets (n=156). Paper 3 took an exploratory approach to identification of potential target groups for prevention of neck/shoulder and low back pain, using cluster analysis of 15 variables on different aspects of working and living conditions (n=1,341). In Paper 4 these clusters or groups were followed up after 5 years with respect to neck/shoulder and low back pain, and care seeking during the follow-up period (n=1,095). Six of the eight questions had high or moderate accuracy and thus can be recommended for questionnaires to study health effects in epidemiological studies. Two questions on bent/twisted work posture and repetitive movements had low accuracy and should be avoided, at least in general population studies. Gender, type of work, and musculoskeletal complaints did not influence the ability to respond to the physical load questions. Level of exposure to awkward work postures was associated with vertical occupational segregation, and this appeared to be most prominent in female-dominated jobs. Female and male workers in such jobs with low status and authority had the overall highest exposure levels. Eleven groups with different working and living conditions were identified. Four of the groups had an increased risk for persistent neck/shoulder or low back pain 5 years after the baseline measurements (OR 2.4 2.6). The working and living conditions of these four groups had quite different features, but were all characterized by an overstrained situation. In three of them, the working and living conditions were rather gender-specific. In conclusion, this thesis emphasizes the need for both reevaluation and redesign of old questionnaire instrument, as well as the requirement for new questions relevant for contemporary work situations. Structural factors in the labor market, such as occupational gender segregation, need to be addressed in order to decrease physical load exposure, especially in female-dominated jobs. Gender sensitive methods are essential in both research and prevention. Different broad-based prevention strategies are needed for different groups, i.e., a selective public health approach in prevention. Cluster analysis seems to be a practicable method for identifying target groups for primary/secondary prevention.