In this study, the association of LBP with personal, occupational and psychosocial factors was investigated. Our findings demonstrated no significant association between LBP and sex, smoking, neuro-psychological disorders, body mass index, type of job, shiftwork, total stress score and stress intensity. Nevertheless, our results demonstrated that LBP was statistically correlated with age and the duration of employment.
The annual prevalence of LBP in the steel industry in our study was 38.5%. The prevalence rate of LBP in different studies was between 11% and 65 %. This notable difference in prevalence rate can be justified by research method, different job categories, demographic characteristics, LBP definition and worker support systems and insurance (11–13).
According to our findings, a significant relationship was found between LBP and age, which was mentioned in numerous previous studies (14, 15); however, this relationship was not confirmed in some studies (16, 17). The acceleration of degenerative changes due to aging may explain the higher prevalence of LBP in older people.
In our study, no association was found between LBP and smoking, which is in line with previous studies (17). However, smoking is reported to be a risk factor for LBP in some other studies (15, 18, 19). Interestingly, a meta-analysis, which was comprised of 27 cross-sectional and 13 cohort studies, demonstrated that smoking cessation can relatively decrease the risk of LBP but, cannot eliminate it (20). It is noteworthy that the very low rate of smoking in our sample size might be because of the reluctance of our participants for honest disclosure of the issue due to the probable repercussions, justifying the discrepancy between our results and previous studies.
According to our study, LBP and work experience are interrelated which is in parallel with previous research (14, 18). The relationship between LBP and the duration of employment was statistically significant in the under 40 years old group. Since people enter the industry in the second or third decade of their life, this age period is when individuals are gaining experience in their work environment through trial and error, thus they are more prone to health-related issues. Entering the fourth decade of life, workers have gained the essential experience and knowledge regarding their occupational setting, duties, and job-related hazards; therefore, the incidence of health problems is expected to diminish with the increase in age and work experience.
In the present study, no association was found between LBP and work type (Industrial or administrative). Similarly, a systematic review conducted by Kwon et al. demonstrated no conclusive evidence regarding a relationship between LBP and work type (21). Moreover, a meta-analysis by Taylor et al. showed that LBP incidence in the general population is similar to different occupational groups (22). On the other hand, a meta-analysis conducted by Griffith et al. illustrated a moderate relation between mechanical workplace risk factors and LBP however, the essence of this association could not be elucidated (23). Furthermore, another study reported that LBP was associated with carrying heavy loads (24).
Our results demonstrated that the total stress score in workers with LBP is similar to healthy individuals. However, this finding is controversial and studies are not conclusive in this regard. Ghaffari and colleagues investigated the relationship between psychosocial factors and LBP using the Nordic questionnaire. Their results showed that among all psychosocial characteristics, only a monotonous job is a risk factor for LBP (12). Kresal et al. showed a significant relationship between LBP and psychosocial stress in professional drivers (24). Similarly, Habibi et al. demonstrated a significant association between LBP and psychosocial factors such as job demand, job content, social support, and job control in nurses (25). Moreover, the incidence of LBP was found to be correlated with job insecurity, unfriendly working environment and job-family incongruity (26). Conversely, Boughattas and colleagues found no relationship between psychosocial factors and LBP in nurses, which is in line with the results of several other studies (27–29). As it was mentioned, the results of previous studies are not congruent regarding this issue; moreover, in the majority of them, job stress was not inspected separately and via standard questionnaires. These studies were conducted using self-reports of some psychosocial factors such as job satisfaction, social support, personality characteristics, and the individual perception of job control. However, we specifically investigated job stress in 6 different domains of workload, role ambiguity, role insufficiency, role conflict, responsibility, and physical environment, based on a standard questionnaire. However, it is worth noting that the term "stress" is a general concept that incorporates all stressful experiences during work and personal life of an individual. Therefore, observing no relationship between job stress and LBP does not preclude its impact on the development and chronicity of LBP. The influence of other psychosocial factors in the process of managing this disease should be considered.
In a systematic review by Mehrdad et al. on the Iranian population, the prevalence of LBP was similar in both males and females which is parallel to our results and previous studies (17, 24). Nevertheless, some studies reported a relationship between gender and LBP (15, 19). This discrepancy may be due to differences in study populations and occupation.
In a study on 1439 steel industry workers, a noticeable relationship was reported between BMI and LBP (16). Similarly, a study conducted on 245 nurses showed that with every unit increase in BMI from 27 kg/m2, the risk of developing LBP will be roughly doubled (30). Although LBP was more common in patients with higher BMI in our study, this difference was not statistically significant.
In this research, no relationship was observed between shiftwork and LBP which is similar to the results of Trezi et al. study (17). However, a direct association between LBP and shiftwork has also been reported (23). Thus, revealing the true nature of the relationship between LBP and shiftwork requires further studies.
Our study had several limitations. For instance, because this was a cross-sectional study, the causal relationship between LBP and some of the factors is not conclusive. Moreover, the healthy worker effect could have also imposed some limitations on the relationship between some risk factors and LBP. Furthermore, self-reported answers might have affected the results. However, we carried out a comprehensive investigation of all three groups of possible LBP risk factors (personal, occupational, and psychosocial) and applied standard questionnaires to increase the validity of our results.