Psychosocial work characteristics and low back pain in daycare (nursery) workers in Japan: a prospective cohort study

Background: Low back pain (LBP) is one of the most common musculoskeletal problems affecting daycare (nursery) workers. We aimed to identify the psychosocial factors influencing LBP in daycare workers. Methods: We conducted a prospective cohort study with a one-year observation period. The baseline sample was a convenience sample of 444 daycare workers from 34 daycare facilities in Nagoya, Japan, and its suburbs. All the data were collected through a questionnaire survey. The question "Where are you currently feeling LBP?"was used to determine whether the subjects suffered from LBP. We examined the prospective relationships of the psychosocial work characteristics, i.e., high job strain, low social support, effort-reward imbalance, and overcommitment, at baseline and LBP after one year. We used multiple logistic regression analyses to calculate the odds ratios of psychosocial work characteristics for the persistence and onset of LBP, adjusted for age, sex, body mass index, smoking, employment status, occupation, and working schedule. Results: At baseline, 270 (60.8%) subjects suffered from LBP. Of 208 who also gave information on LBP one year later, 176 (84.6%) suffered from the persistence of LBP. Low social support at baseline was significantly related to persistent LBP one year later. The incidence of persistent LBP was 89.9% and 80.0% among those with and without low social support at baseline, respectively. The adjusted odds ratio (95% confidence interval) of low social support at baseline for the persistence of LBP was 2.43 (1.01-5.87). Of 150 who were without LBP at baseline and provided information on LBP one year later, 45 (30.0%) suffered from the onset of LBP. None of the psychosocial work characteristics showed significant relationships with the onset of LBP one year later. Conclusion: Low social support was related to the persistence, but not to the onset of LBP in a prospective cohort analysis among daycare workers in Japan. High job strain, ERI, or overcommitment did not show a significant prospective effect on LBP.