Identification of risk factors for new-onset sciatica in Japanese workers: findings from the Japan epidemiological research of Occupation-related Back pain study.

ABSTRACT

STUDY DESIGN: Two-year, prospective cohort data collected for the Japan epidemiological research of Occupation-related Back pain study were used for the analysis. OBJECTIVE: To identify potential risk factors for the development of new-onset sciatica in initially symptom-free Japanese workers with no history of sciatica. SUMMARY OF BACKGROUND DATA Although the associations between individual and occupational factors and cases of new-onset sciatica are established, the effect of psychosocial factors on the development of sciatica has still not been adequately clarified. METHODS: In total, 5310 participants responded to a self-administered baseline questionnaire (response rate 86.5%). Furthermore, 3194 (60.2%) completed both 1- and 2-year follow-up questionnaires. The baseline questionnaire assessed individual characteristics, ergonomic work demands, and work-related psychosocial factors. The outcome of interest was new-onset sciatica with or without low back pain during the 2-year follow-up period. Incidence was calculated for participants who reported no low back pain in the preceding year and no history of lumbar radicular pain (sciatica) at baseline. Logistical regression assessed risk factors associated with new-onset sciatica. RESULTS: Of 765 eligible participants, 141 (18.4%) reported a new episode of sciatica during the 2-year follow-up. In crude analysis, significant associations were found between new-onset sciatica and age and obesity. In adjusted analysis, significant associations were found for obesity and mental workload in a qualitative aspect after controlling for age and sex. Consequently, in multivariate analysis with all the potential risk factors, age and obesity remained statistically significant (odds ratios 1.59, 95% confidence interval 1.01-2.52; odds ratios 1.77, 95% confidence interval 1.17-2.68, respectively). CONCLUSION: In previously asymptomatic Japanese workers, the risk of developing new-onset sciatica is mediated by individual factors. Our findings suggest that the management of obesity may prevent new-onset sciatica. LEVEL OF EVIDENCE 3.