INTRODUCTION
Low back pain (LBP) is the most common musculoskeletal complaints and the most frequent causes of life with disabilities. The prevalence is ranged from 20-33% in all patients with musculoskeletal pain complaints worldwide. LBP is a complaint that is not only experienced by elderly people but also be found in all age categories including productive adults [18]. A study in the United States shows that LBP occurs in one to three adults under the age of 65 each year, which indicates that middle adults (30-60 years) are likely to develop LBP [23]. Middle adulthood, also known as the transitional period, is a period marked by physical and psychological changes, as well as a period of peak productivity, particularly for those aged 40-45 [21,22]. In terms of prevention, the most likely LBP occurs in middle age, and there are several consequences that include not only health burden, but also financial problems; therefore, it is critical to determine what risk factors are associated with LBP in those ages. This is especially true in countries with a high proportion of middle-aged people, such as Indonesia.
There are many risk factors that affect the prevalence of LBP in middle adulthood. These factors are namely divided into three categories; individual, occupational, and psychosocial factors. Age, gender, body mass index (BMI), family history of illness, smoking habits, alcohol consumption, being married, female, and lack of routine exercises are categorized as individual risk factors [35]. Whereas, occupational risk factors, for examples 11-80% of these factors are involved in ergonomic factors such as sitting over, lifting weights, and bending over [10]. The population with the highest prevalence of LBP in small city in West Jawa, Jatinangor is the productive age (18-65 years). This is possibly due to the high physical and occupational loads that demanding a certain body position during work for prolonged period of time [27].
Although various studies have examined the incidence, prevalence, and risk factors for LBP in middle adulthood, only a few research has studied regarding the prevalence and risk factors of LBP especially among middle-aged adults in Indonesia, a country with the fourth rank of the number of population with the productive aged people is in the highest proportion of population (15-64 years, 70.72%) [1]. In addition, LBP could cause economic losses and decreased productivity of the patients [14,33]. Therefore, it is important to identify both modifiable and non-modifiable risk factors to prevent LBP. Based on the reasons mentioned above, this study was conducted to determine factors associated with LBP among middle-aged adults in Indonesia.
MATERIALS AND METHODS
This study was approved by Clinical Study Ethics Commitee of Universitas Pembangunan Nasional Veteran Jakarta, Indonesia (57/I/2021/KEPK). The respondents had given the approval by informed consent to participate in this research. All methods were carried out in accordance with the Declaration of Helsinki.
Study design and participants
A total of 3005 Indonesia middle aged adults were included of whom 1681 were male and 1324 were female. All participants gave consent and approval before fillinged the questionnaires in google forms. Data were collected from February 4 to March 27, 2021. The sociodemographic and occupational related questions, LBP questions and perceived stress scale (PSS) questionnaire were included.
Outcome measures
Assessment of LBP
Participants’ LBP events within the last 12 months were evaluated using low back part of Indonesian version of Standardized Nordic Musculoskeletal Questionnaire which was translated by Wicaksono [41]. Reliability score of this questionnaire was tested by Wicaksono [41] with a result of cronbach’s alpha score of 0.945. Therefore, all items in this questionnaire is valid and reliable.
Assessment of psychosocial risk factors
Stress levels of participants were evaluated through PSS-10. PSS is a 10-item questionnaire which uses likert scale where “0=none and 4=very often” consisting six positive items and four negative items (number 4, 5, 7, and 8).
Reliability test of Indonesian version of PSS-10 was studied by Pin and Effendy [31] with a result of cronbach’s alpha score of 0.96. Our study also tested the validity and reliability of Indonesian’s version of PSS-10 which showed all items in this questionnaire is valid and reliable (Cronbach’s alpha score, 0.775). Total score of 0-13 demonstrates mild stress; 14-26 shows moderate stress and 27-40 shows severe stress.
Statistical analysis
Our research used SPSS ver. 22 for all analyses (IBM Corp, Armonk, NY, USA). Univariate analyses are reported as numbers and percentages. Independent variables were analyzed using chi-square test, Kolmogorov-smirnov test. Statistical significance was set at p<0.05. Logistic regression method was used in this study as the multivariate analysis to determine the risk factors of LBP.
RESULTS
This study included 3005 middle-aged adults, with 35.4% of respondents aged 50-60 years. Males made up 55.9% of them. The 66.4% of respondents held a bachelor’s, master’s, or doctoral degree. The 89.7% of respondents were married. The majority of jobs were held by private employees (29.5%). The vast majority of respondents (74.7%) did not smoke. Although 39.7% of respondents rarely exercised, 47.3% of respondents had a normal BMI.
According to stress scale calculations, the majority of respondents (53.7%) had moderate stress with a total stress scale value of 14-26. The 83.3% of respondents did not have a chronic disease. The majority of respondents earned between Rupiah (Rp.) 5000000 and Rp. 10000000 (27.3%). The majority of respondents (68.2%) had worked for more than 10 years. The 51.5% of respondents spent more than 8 hours per day working, with the majority sitting 4 hours per day (59.5%) and standing more than 4 hours per day while working (65.9%) (Fig. 1 and Table 1).
Univariate analysis revealed that factors such as gender (p=0.001), level of education (p=0.012), physical exercise (p=0.002), BMI (p=0.006), stress scale (p=0.003), and years of work experience (p=0.002) were significantly associated with LBP in the previous 12 months (Table 2). In terms of occupation, nurses had a 62.2% prevalence of LBP in a 12-month period. Other occupations include lawyer (60.0%), state-owned corporation (55.3%), entrepreneur (55.2%), government (51.2%), lecturer (50.3%), and physician (50.0%).
In multivariate analysis, the following factors were significantly associated with LBP : female gender (odds ratio [OR], 1.31; 95% confidence interval [CI], 1.098-1.545; p=0.002), lack of physical exercise (OR, 0.87; 95% CI, 0.794-0.959; p=0.005), higher BMI (OR, 1.09; 95% CI, 1.009-1.187; p=0.002), stress level (OR, 1.26; 95% CI, 1.088-1.458; p=0.002), and years of work experience (OR, 1.11; 95% CI, 1.001-1.225; p=0.047) (Table 3).
DISCUSSION
LBP has a negative impact on productivity and an individual’s overall well-being [24]. The prevalence of LBP is extremely high, and it is a major cause of disability [11]. Several factors influence the occurrence of LBP, including sociodemographic, ergonomic, and psychosocial factors [25].
LBP prevalence in Indonesia middle age adult
Our findings revealed that the prevalence of LBP in middle-aged adult Indonesia was 44.29% at 12 months. This study confirmed previous findings that LBP is most common in people aged 40 to 80 years old, with a prevalence of 23.2%± 2.9% [18]. As matter of fact, The prevalence of LBP varies between countries [27]. According to other systematic cohort studies, the prevalence of LBP in the general population ranges 15-45% [30]. In Saudi Arabia, the prevalence of LBP in the general population is 18.8% [3]. According to a study on the prevalence of LBP in Japan, the 1-month prevalence is 35.7% and the lifetime prevalence is 83.4% [13].
Risk factors of LBP in middle age adult
Gender was found to be associated with LBP in our study. In line with previous research, we discovered that the prevalence of LBP was higher in females than in males [7,19,27,35]. Females have a lower pain threshold than men, so they are more likely to report LBP symptoms than men [28,32]. Other research has found that females are at a higher risk of LBP due to hormonal imbalances. The hormonal imbalances that occur during pregnancy cause the spinal ligaments to loosen, reducing the strength of the lower back muscles and increasing the risk of LBP. Females tend to have a lower pain threshold than men, therefore they often report the symptoms of LBP than men [8,10,15]. Fernández-de-las-Peñas et al. [12] proposed that menopausal osteoporosis caused LBP in women, while another study concluded that obesity is associated with LBP in women [34]. Housework [27], and menstruation were two other factors that contributed to females having more LBP menstruation [37,39,40].
In line with previous findings [17,35], our findings indicated that BMI was a significant risk factor for LBP. Şimşek et al. [35] discovered that people with higher BMI had 0.9 times more LBP. A study of healthcare workers found that having a high BMI was associated with LBP [2,5]. Possible explanations include (1) increasing mechanical compression in the lumbar spine during movements in obese people possibly enhances mechanical burden, (2) the likehood of having of an accident thus possibly increasing the risk of LBP, and (3) adipose tissues produce produces some proinflammatory cytokines (e.g., tumor necrosis factor-α, interleukin-6) that trigger the release of C-reactive protein (CRP), and this statement was supported by the fact that females with normal waist circumference and high CRP have tendency to report LBP than females with low CRP [5,34].
Consistent with other studies, we discovered that LPB is more common in people who rarely or never exercise [5,10,20,32,35]. LBP is caused by shortened and weakened back muscles, which causes spinal misalignment. Exercise reduces the occurrence of LBP by (1) lengthening the back muscles, which support and keep the spine in proper alignment. Regular exercise increases blood supply to the muscles, joints, and intravertebral discs of the spine, reducing injury and promoting repair [10,32]. And (2) exercise lowers stress and the level of cortisol, which rises in stressful situations [6,29,38]. Other studies have found that strengthening the spinal muscles through exercises like stretching or aerobic training reduces LBP by 30% in terms of intensity and disability [34].
According to the findings of this study, the severity of stress had a significant correlation with LBP. This study agreed with a Korean study that found severe stress was associated with a 2.8-fold increase in the risk of chronic LBP compared to the general population [9]. Stress causes cortisol to be secreted in the bloodstream. Cortisol is a powerful anti-inflammatory hormone, and repeated high levels of cortisol promote cortisol defect. As a result, oxidative stress, free radical release, and cellular injury occur, resulting in chronic pain [16]. Higher cortisol levels are associated with a lower strength of lumbar muscles, resulted in LBP [6,10].
In our study, years of work experience were found to be significantly related to LBP. This finding is consistent with a study that discovered nurses with 5 years of experience were three times more likely to suffer from LBP [4,26,36]. This is because nurses are more likely to face physical and psychological hazards throughout their careers [26]. This fact corroborated our findings that nurses have the highest prevalence of LBP in the last year. Other studies in Slovenia [36] and Eastern Ethopia [26] have found similar results.
The study’s limitations were (1) the sampling method, which did not use probability (random) sampling due to the COVID-19 pandemic, and thus the results could be biased. However, we present a large number of pupulation to a local survey. (2) The data on height and body weight may not be entirely accurate because, due to the pandemic, measurements of height and body weight were not possible. (3) We did not ask about other pathologies that cause symptoms similar to LBP, such as urinary tract infections or urolithiasis. This high prevalence may have obscured the presence of additional pathologies. And (4) we did not ask about previous spine pathologies, which could have resulted in back pain at the time.
CONCLUSION
In Indonesia, LBP is quite common among middle-aged adults. As country with a high proportion of middle-aged adults, this emphasizes the importance of disease prevention in order to reduce economic and family burden. Female gender, a high BMI, a lack of physical activity, a high stress level, and years of work experience are all risk factors for LBP. Individual, occupational, and psychosocial risk factors that may exacerbate LBP in the future should be identified and avoided by middle-aged adults in Indonesia.
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