Potential Risk Factors of Persistent Low Back Pain Developing from Mild Low Back Pain in Urban Japanese Workers

<div><p>Study Design</p><p>Two-year, prospective cohort data from the Japan epidemiological research of occupation-related back pain study in urban settings were used for this analysis.</p><p>Objective</p><p>To examine the association between aggravated low back pain and psychosocial factors among Japanese workers with mild low back pain.</p><p>Summary of Background Data</p><p>Although psychosocial factors are strongly indicated as yellow flags of low back pain (LBP) leading to disability, the association between aggravated LBP and psychosocial factors has not been well assessed in Japanese workers.</p><p>Methods</p><p>At baseline, 5,310 participants responded to a self-administered questionnaire including questions about individual characteristics, ergonomic work demands, and work-related psychosocial factors (response rate: 86.5%), with 3,811 respondents completing the 1-year follow-up questionnaire. The target outcome was aggravation of mild LBP into persistent LBP during the follow-up period. Incidence was calculated for the participants with mild LBP during the past year at baseline. Logistic regression was used to explore risk factors associated with persistent LBP.</p><p>Results</p><p>Of 1,675 participants who had mild LBP during the preceding year, 43 (2.6%) developed persistent LBP during the follow-up year. Multivariate analyses adjusted for individual factors and an ergonomic factor found statistically significant or almost significant associations of the following psychosocial factors with persistent LBP: interpersonal stress at work [adjusted odds ratio (OR): 1.96 and 95% confidence interval (95%CI): 1.00–3.82], job satisfaction (OR: 2.34, 95%CI: 1.21–4.54), depression (OR: 1.92, 95%CI: 1.00–3.69), somatic symptoms (OR: 2.78, 95%CI: 1.44–5.40), support from supervisors (OR: 2.01, 95%CI: 1.05–3.85), previous sick-leave due to LBP (OR: 1.94, 95%CI: 0.98–3.86) and family history of LBP with disability (OR: 1.98, 95%CI: 1.04–3.78).</p><p>Conclusions</p><p>Psychosocial factors are important risk factors for persistent LBP in urban Japanese workers. It may be necessary to take psychosocial factors into account, along with physical work demands, to reduce LBP related disability.</p></div

Adjusted odds ratios of the baseline factors for persistent low back pain (LBP) with work disability; factors with crude odds ratio P values<0.1.

<p>OR: odds ratio, CI: confidence interval, LBP: low back pain</p>a<p>Adjusted for age, gender, obesity, smoking habits, and education.</p>b<p>Adjusted for age, gender, obesity, smoking habits, education, and manual handling of materials at work.</p>c<p>Bending, twisting, lifting, and pushing: ≥ half of the day was considered frequent.</p>d<p>Hours of desk work: longer than 6 hours per day was considered to be static posture.</p>e<p>Work-related stress factors assessed with the brief job stress questionnaire: not feeling stressed, feeling stressed: the 5 original responses were reclassified into “not feeling stressed”, where low, slightly low and moderate were combined, and “feeling stressed”, where slightly high and high were combined.</p

The associations between magnetic resonance imaging findings and low back pain: A 10-year longitudinal analysis

<div><p>Purpose</p><p>To conduct a 10-year longitudinal analysis of the relationship between magnetic resonance imaging (MRI) findings and low back pain (LBP).</p><p>Materials and methods</p><p>Ninety-one volunteers with a history of LBP, but without current LBP were recruited between 2005 and 2006. Participants’ baseline demographics and MRI findings were recorded. All volunteers were invited for a follow-up MRI in 2016; of these, 49 volunteers (53.8%) participated in the follow-up. We enquired whether they had LBP history during the 10 years between the baseline and follow-up examinations. Sagittal T1 and T2-weighted MRI were used to assess the intervertebral space from T12/L1 to L5/S1. We evaluated the presence of disc degeneration by Pfirrmann’s grading system, disc bulging, high intensity zone (HIZ), spondylolisthesis, and any type of Modic changes in the follow-up MRIs. We compared the follow-up MRI findings with the baseline findings; the progress of each finding over the 10 years were also compared between the groups with (n = 36) and without (n = 13) LBP.</p><p>Results</p><p>Average age of the study participants at follow-up was 44.8 years; 25 were female and 24 were male. Average age, sex, body mass index, and smoking habits of those who did and did not participate in the follow-up study, as well as the demographic characteristics of those who did and did not have LBP history during the 10 years, were not significantly different. Compared with the group without LBP history, the group that had LBP history during the 10 years did not have a significantly increased prevalence of disc degeneration, disc bulging, and HIZ in the follow-up and baseline MRIs. Spondylolisthesis and any type of Modic changes were also not associated with LBP history during the 10 years.</p><p>Conclusions</p><p>Follow-up MRI findings consistent with Pfirrmann grading ≥4, disc bulging, HIZ, spondylolisthesis, and any type of Modic changes were not associated with LBP history during the 10 years between the baseline and follow-up study. The progresses of these findings were also not associated with the LBP history. In addition, baseline MRI findings were not associated with LBP history during the 10 years; therefore, our data suggest that baseline MRI findings cannot predict future LBP.</p></div

Participant characteristics: psychometric testing of the STarT-J (n = 2000).

<p>Participant characteristics: psychometric testing of the STarT-J (n = 2000).</p

Score distribution of STarT-J items and risk group distribution (n = 2000).

<p>Score distribution of STarT-J items and risk group distribution (n = 2000).</p

Mean STarT-J scores for participants with different numbers of somatic symptoms.

<p>The linear trend was tested using the Jonckheere-Terpstra test (p < 0.0001). STarT-J: The Japanese version of the STarT Back Tool. Number of somatic symptoms was assessed by the Brief Symptom Inventory somatization scale: a response of “moderately,” “quite a bit,” or “extremely” to an item was interpreted as the presence of that somatic symptom, and thus counted.</p

Details of the participants of the follow-up study.

<p>Details of the participants of the follow-up study.</p

Demographic data of the participants who did and did not participate in the follow-up study.

<p>Demographic data of the participants who did and did not participate in the follow-up study.</p

Mean number of absences for the three STarT-J risk groups.

<p>The linear trend was tested using the Jonckheere-Terpstra test (p < 0.0001). STarT-J: The Japanese version of the STarT Back Tool.</p

Forty-three reflective markers.

<p>(a) Posterior view, (b) anterior view, and (c) lateral view.</p