J Orthop Sci (2015) 20:23–30 DOI 10.1007/s00776-014-0644-x
ORIGINAL ARTICLE
The prevalence and characteristics of low back pain among sitting workers in a Japanese manufacturing company Gen Inoue · Masayuki Miyagi · Kentaro Uchida · Tetsuhiro Ishikawa · Hiroto Kamoda · Yawara Eguchi · Sumihisa Orita · Kazuyo Yamauchi · Masashi Takaso · Kei‑ichi Tsuchiya · Kazuhisa Takahashi · Seiji Ohtori
Received: 26 December 2013 / Accepted: 24 August 2014 / Published online: 8 September 2014 © The Japanese Orthopaedic Association 2014
Abstract Background Low back pain (LBP) is a major public health problem and the most common cause of workers’ disability, resulting in substantial economic burden in terms of workers’ compensation and medical costs. Sitting is a recognized potential risk factor for developing LBP. Therefore, eliminating risk factors associated with working conditions and individual work capacity may be beneficial in preventing LBP in sitting workers. The purpose of this prospective cross-sectional study is to investigate the prevalence of LBP and examine risk factors that contribute to the development of LBP in sitting workers at an electronics manufacturing company. Methods A cross-sectional survey was administered to all subjects to assess the prevalence of LBP persisting for at least 48 h during the recent week. Data on demographic characteristics and potential risk factors for LBP were collected at routine annual check-ups. Patients with LBP completed the Roland-Morris Disability Questionnaire (RDQ), which provided information on the attributes of LBP. Univariate and multivariate regression analyses examined the association between LBP and potential risk factors. Results Of the 1,329 sitting workers, 201 (15.1 %) acknowledged experiencing LBP during the recent week. In G. Inoue (*) · M. Miyagi · K. Uchida · M. Takaso Department of Orthopaedic Surgery, Kitasato University School of Medicine, 1‑15‑1, Kitasato, Minami‑ku, Sagamihara, Kanagawa 252‑0374, Japan e-mail: ginoue@kitasato‑u.ac.jp T. Ishikawa · H. Kamoda · Y. Eguchi · S. Orita · K. Yamauchi · K. Tsuchiya · K. Takahashi · S. Ohtori Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan K. Tsuchiya TDK Narita factory, Narita, Chiba, Japan
female workers, weight and body mass index were significantly correlated with the RDQ score. Univariate analyses identified male sex, prior history of LBP, height ≥170 cm, and weight ≥70 kg as significant risk factors of LBP. Multivariate logistic regression analyses identified prior history of LBP and past history of lumbar spine surgery as significant risk factors of LBP. Conclusions This study characterized the prevalence and attributes of LBP in Japanese sitting workers and provided information about potential risk factors contributing to occurrence of LBP in the workplace.
Introduction Low back pain (LBP) is a major public health problem adversely affecting patients’ well-being and quality of life (QOL), and contributing substantially to the burden of disease globally [1]. The World Health Organization (WHO) measured the global burden of disease from 1990 to 2010 and estimated that as a result of musculoskeletal disorders, individuals on average had lost a total of 6.8 disabilityadjusted life years (DALYs), representing the sum of years lived with disability. Accounting for nearly 50 % of musculoskeletal disorders, the frequency of LBP continues to rise, ranking the condition first among 289 diseases within the Asian Pacific as well as countries globally [2, 3]. The etiology of LBP is not fully understood, but is purported to be multi-factorial with individual, physical, and psychosocial factors contributing to its development and persistence. Previous studies have identified several risk factors for LBP including age, female sex, educational status, obesity, smoking, sleep deprivation, prolonged driving, and computer usage [4–10]. Psychosocial factors, such as stress and depression, also play a role [11, 12].
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Sitting potentially contributes to LBP due to the accompanying increased load placed on the lumbar spine [13]. Nachemson and Elfström demonstrated that the magnitude of load increases markedly during sitting compared to during standing [14]. Sitting for periods exceeding half the work day in combination with awkward postures or frequently working in a forward bent position increases the likelihood of LBP [15]. In Europe, the prevalence of LBP in occupations that require the worker to sit for the majority of the work day is significantly higher than that in the general population [16, 17]. However, few studies have specifically assessed the risk factors and epidemiology of LBP in Japanese sitting workers. In the workplace, prevention focused on eliminating risk factors associated with working conditions and individual work capacity is very important. Accordingly, we investigated the prevalence of LBP in sitting factory workers and examined the risk factors potentially contributing to its development.
Materials and methods Study design We conducted a cross-sectional survey of sitting factory workers at an electronics manufacturing company in Japan in order to investigate the prevalence of LBP and its associated factors. Additionally, we analyzed the characteristics of LBP using the Roland-Morris Disability Questionnaire (RDQ), a self-administered measure of disability in LBP. The RDQ employs a 24-point scale in which higher scores reflect greater levels of disability [18]. The ethics committee of our institution approved the study design, and informed consent was obtained from each worker. Subjects At the TDK Narita factory and its affiliated companies, general check-ups, including routine internal medicine counseling and physical assessments, are registered with the occupational health clinic at the factory and performed on all workers annually. In total, 2,025 workers were employed at this electronics manufacturing company, of whom 1,330 workers who sat for periods exceeding 50 % of their work time were included in the present study. All eligible subjects underwent a general check-up and completed the survey on LBP within several days of the examination. In accordance with the Japanese Labour Standards Law, all employees worked for 8 h daily for a weekly total of 40 h. Workers ate lunch and rested for 45 to 60 min each day. Duties of the sitting workers entailed using a computer, strenuous arm movements, lifting, some rotation of
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the trunk, and carrying light loads. Vibration of the whole body or continuous awkward position was not loaded. Demographic variables, including age, gender, height, and weight were recorded. Data on other potential risk factors for LBP, including the frequency of regular exercise, present or past smoking habits, history of LBP lasting for at least 1 week, and history of lumbar spine surgery were also collected. Exercise was defined as a moderate to competitive level of physical activity and included activities such as jogging, tennis, swimming, gymnastics, and soccer, which were performed for more than 30 min per day [19]. Smoking habit was characterized as daily use of more than five cigarettes for duration of at least 1 month [20]. Additionally, workers were queried about work-related physical factors, such as the duration of computer use (≥4 h) and whether daily work routinely involved standing activities, such as reaching, forward or backward bending, or lifting objects for more than 1 h per day. In order to estimate the prevalence of LBP in the study sample, a cross-sectional survey was administered to all eligible sitting workers. LBP was defined as pain localized between the costal margin and the inferior gluteal folds, as indicated in a figure included in the questionnaire [21]. The RDQ was then administered to workers who acknowledged experiencing LBP lasting for at least 48 h during the current week. All sitting workers in the factory were asked to participate voluntarily in the study and were informed of the study’s aim to improve future work conditions. Univariate analyses of each variable were performed for workers with and without LBP, and factors with P values
ORIGINAL ARTICLE
The prevalence and characteristics of low back pain among sitting workers in a Japanese manufacturing company Gen Inoue · Masayuki Miyagi · Kentaro Uchida · Tetsuhiro Ishikawa · Hiroto Kamoda · Yawara Eguchi · Sumihisa Orita · Kazuyo Yamauchi · Masashi Takaso · Kei‑ichi Tsuchiya · Kazuhisa Takahashi · Seiji Ohtori
Received: 26 December 2013 / Accepted: 24 August 2014 / Published online: 8 September 2014 © The Japanese Orthopaedic Association 2014
Abstract Background Low back pain (LBP) is a major public health problem and the most common cause of workers’ disability, resulting in substantial economic burden in terms of workers’ compensation and medical costs. Sitting is a recognized potential risk factor for developing LBP. Therefore, eliminating risk factors associated with working conditions and individual work capacity may be beneficial in preventing LBP in sitting workers. The purpose of this prospective cross-sectional study is to investigate the prevalence of LBP and examine risk factors that contribute to the development of LBP in sitting workers at an electronics manufacturing company. Methods A cross-sectional survey was administered to all subjects to assess the prevalence of LBP persisting for at least 48 h during the recent week. Data on demographic characteristics and potential risk factors for LBP were collected at routine annual check-ups. Patients with LBP completed the Roland-Morris Disability Questionnaire (RDQ), which provided information on the attributes of LBP. Univariate and multivariate regression analyses examined the association between LBP and potential risk factors. Results Of the 1,329 sitting workers, 201 (15.1 %) acknowledged experiencing LBP during the recent week. In G. Inoue (*) · M. Miyagi · K. Uchida · M. Takaso Department of Orthopaedic Surgery, Kitasato University School of Medicine, 1‑15‑1, Kitasato, Minami‑ku, Sagamihara, Kanagawa 252‑0374, Japan e-mail: ginoue@kitasato‑u.ac.jp T. Ishikawa · H. Kamoda · Y. Eguchi · S. Orita · K. Yamauchi · K. Tsuchiya · K. Takahashi · S. Ohtori Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan K. Tsuchiya TDK Narita factory, Narita, Chiba, Japan
female workers, weight and body mass index were significantly correlated with the RDQ score. Univariate analyses identified male sex, prior history of LBP, height ≥170 cm, and weight ≥70 kg as significant risk factors of LBP. Multivariate logistic regression analyses identified prior history of LBP and past history of lumbar spine surgery as significant risk factors of LBP. Conclusions This study characterized the prevalence and attributes of LBP in Japanese sitting workers and provided information about potential risk factors contributing to occurrence of LBP in the workplace.
Introduction Low back pain (LBP) is a major public health problem adversely affecting patients’ well-being and quality of life (QOL), and contributing substantially to the burden of disease globally [1]. The World Health Organization (WHO) measured the global burden of disease from 1990 to 2010 and estimated that as a result of musculoskeletal disorders, individuals on average had lost a total of 6.8 disabilityadjusted life years (DALYs), representing the sum of years lived with disability. Accounting for nearly 50 % of musculoskeletal disorders, the frequency of LBP continues to rise, ranking the condition first among 289 diseases within the Asian Pacific as well as countries globally [2, 3]. The etiology of LBP is not fully understood, but is purported to be multi-factorial with individual, physical, and psychosocial factors contributing to its development and persistence. Previous studies have identified several risk factors for LBP including age, female sex, educational status, obesity, smoking, sleep deprivation, prolonged driving, and computer usage [4–10]. Psychosocial factors, such as stress and depression, also play a role [11, 12].
13
24
Sitting potentially contributes to LBP due to the accompanying increased load placed on the lumbar spine [13]. Nachemson and Elfström demonstrated that the magnitude of load increases markedly during sitting compared to during standing [14]. Sitting for periods exceeding half the work day in combination with awkward postures or frequently working in a forward bent position increases the likelihood of LBP [15]. In Europe, the prevalence of LBP in occupations that require the worker to sit for the majority of the work day is significantly higher than that in the general population [16, 17]. However, few studies have specifically assessed the risk factors and epidemiology of LBP in Japanese sitting workers. In the workplace, prevention focused on eliminating risk factors associated with working conditions and individual work capacity is very important. Accordingly, we investigated the prevalence of LBP in sitting factory workers and examined the risk factors potentially contributing to its development.
Materials and methods Study design We conducted a cross-sectional survey of sitting factory workers at an electronics manufacturing company in Japan in order to investigate the prevalence of LBP and its associated factors. Additionally, we analyzed the characteristics of LBP using the Roland-Morris Disability Questionnaire (RDQ), a self-administered measure of disability in LBP. The RDQ employs a 24-point scale in which higher scores reflect greater levels of disability [18]. The ethics committee of our institution approved the study design, and informed consent was obtained from each worker. Subjects At the TDK Narita factory and its affiliated companies, general check-ups, including routine internal medicine counseling and physical assessments, are registered with the occupational health clinic at the factory and performed on all workers annually. In total, 2,025 workers were employed at this electronics manufacturing company, of whom 1,330 workers who sat for periods exceeding 50 % of their work time were included in the present study. All eligible subjects underwent a general check-up and completed the survey on LBP within several days of the examination. In accordance with the Japanese Labour Standards Law, all employees worked for 8 h daily for a weekly total of 40 h. Workers ate lunch and rested for 45 to 60 min each day. Duties of the sitting workers entailed using a computer, strenuous arm movements, lifting, some rotation of
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the trunk, and carrying light loads. Vibration of the whole body or continuous awkward position was not loaded. Demographic variables, including age, gender, height, and weight were recorded. Data on other potential risk factors for LBP, including the frequency of regular exercise, present or past smoking habits, history of LBP lasting for at least 1 week, and history of lumbar spine surgery were also collected. Exercise was defined as a moderate to competitive level of physical activity and included activities such as jogging, tennis, swimming, gymnastics, and soccer, which were performed for more than 30 min per day [19]. Smoking habit was characterized as daily use of more than five cigarettes for duration of at least 1 month [20]. Additionally, workers were queried about work-related physical factors, such as the duration of computer use (≥4 h) and whether daily work routinely involved standing activities, such as reaching, forward or backward bending, or lifting objects for more than 1 h per day. In order to estimate the prevalence of LBP in the study sample, a cross-sectional survey was administered to all eligible sitting workers. LBP was defined as pain localized between the costal margin and the inferior gluteal folds, as indicated in a figure included in the questionnaire [21]. The RDQ was then administered to workers who acknowledged experiencing LBP lasting for at least 48 h during the current week. All sitting workers in the factory were asked to participate voluntarily in the study and were informed of the study’s aim to improve future work conditions. Univariate analyses of each variable were performed for workers with and without LBP, and factors with P values
