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Potential Risk Factors for New Onset of Back Pain Disability in Japanese Workers: Findings From the Japan Epidemiological Research of Occupation-Related Back Pain Study

Matsudaira, Ko, MD, PhD*; Konishi, Hiroaki, MD, PhD; Miyoshi, Kota, MD, PhD; Isomura, Tatsuya, MSc§; Takeshita, Katsushi, MD, PhD; Hara, Nobuhiro, MD; Yamada, Koji, MD*; Machida, Hideto, MD, PhD

doi: 10.1097/BRS.0b013e3182498382
Occupational Health/Ergonomics

Study Design. Two-year, prospective cohort data from the Japan epidemiological research of occupation-related back pain study were used for this analysis.

Objective. To examine the association between a new onset of low back pain (LBP) with disability and potential risk factors among initially symptom-free Japanese workers.

Summary of Background Data. Despite strong evidence that psychosocial issues may influence LBP onset among symptom-free persons, these and other LBP risk factors have not been well investigated in the Japanese workplace.

Methods. Of 5310 participants responding to a self-administered baseline questionnaire (response rate: 86.5%), 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 LBP with disability during the follow-up period. Incidence was calculated for the participants who reported no LBP during the past year at baseline. Logistic regression was used to explore risk factors associated with new-onset LBP with disability.

Results. Of 836 participants who were symptom-free during the preceding year, 33 (3.9%) reported LBP with disability during the 2-year follow-up. In univariate analyses, “history of LBP,” “frequent lifting,” “interpersonal stress at workplace,” and “monotonous tasks” were all significant predictors of LBP incidence. All of these factors remained statistically significant or almost significant in the multivariate analysis adjusting for the other variables as well as age and sex: adjusted odds ratio (OR) and 95% confidence interval (95% CI) for history of LBP (OR: 3.25, 95% CI: 1.53–6.91), frequent lifting (OR: 3.77, 95% CI: 1.16–12.3), interpersonal stress at workplace (OR: 2.42, 95% CI: 1.08–5.43), and monotonous tasks (OR: 2.21, 95% CI: 0.99–4.94).

Conclusion. Both ergonomic and work-related psychosocial factors may predict the development of LBP with disability among previously asymptomatic Japanese workers. Thus, workplace interventions aimed at reducing the incidence of LBP should focus on both ergonomic and psychosocial stress.

The association was examined between new-onset low back pain with disability and potential risk factors among Japanese workers who were initially symptom-free. Results suggest that in addition to ergonomic factors, work-related psychosocial factors are also significant in the development of future back pain disability in initially symptom-free Japanese workers.

*Clinical Research Center for Occupational Musculoskeletal Disorders, Kanto Rosai Hospital, Kanagawa, Japan

Department of Orthopaedic Surgery, Nagasaki Rosai Hospital, Nagasaki, Japan

Spine Center, Yokohama Rosai Hospital, Kanagawa, Japan


Department of Orthopaedic Surgery, the University of Tokyo, Tokyo, Japan

Department of Orthopaedic Surgery, Kanto Rosai Hospital, Kanagawa, Japan.

Address correspondence and reprint requests to Ko Matsudaira, MD, PhD, Clinical Research Center for Occupational Musculoskeletal Disorders, Kanto Rosai Hospital, 1-1 Kizukisumiyoshicho, Nakahara-ku, Kawasaki 211-8510, Japan; E-mail:

Acknowledgment date: June 6, 2011. First revision date: September 2, 2011. Second revision date: December 28, 2011. Acceptance date: December 29, 2011.

The manuscript submitted does not contain information about medical device(s)/drug(s).

No funds were received in support of this work.

No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.

© 2012 Lippincott Williams & Wilkins, Inc.