In the present study, the association between low back pain and bad posture was quite significant (P<0.001) (Table -2). People who are in the regular (grade 3) bad posture group had a more than 100 times (OR = 128.2, Table -2) greater chance of developing low back pain compared to people who were in the occasional (grade 2) and rarely (grade 1) bad posture groups. The bad posture increases the intramuscular pressure in the paraspinal muscles and pressure inside the intervertebral discs [20
]. Degeneration of the lumbar intervertebral disc is regarded as a common cause of chronic low back pain (CLBP). The etiology of lumbar disc degeneration (LDD) is complex and not fully explained. LDD is considered to be a multi factorial disorder involving numerous genetic and environmental factors and their interactions [22
]. Heavy physical loading, trauma, bending, twisting and prolonged non-neutral work postures have been suggested to be associated with disc degeneration [23
]. These may be some of the reasons why bad posture is significantly associated with the development of low back pain.
In this study regular exercise had a significant protective effect on low back pain (P<0.001).
People who fell into the group that rarely (grade1) involve in physical exercises have a twenty five times (OR= 24.5, Table 2) greater chance of developing low back pain compared to people who fell into the group that regularly take part in (grade 3) physical exercises. According to a study done in Sri Lanka taking part in exercises such as walking and running more than three times a week had a significant protective effect on low back pain [13
]. Physical exercise has consistent evidence for primary prevention of low back pain compared to no activity [19
]. Several low back pain (LBP) studies have emphasized the important role of paraspinal muscle morphology on the etiology, prognosis, and management of low back pain. The patients with LBP have smaller multifidus muscle cross-sectional area (CSA) compared with asymptomatic control patients who are healthy [24
]. Back muscles act to support the spine and maintain the stability of the spine. The weakness of back muscles such as multifidus and Erector spinae can lead to low back pain and is known as a main cause of recurrence [25
]. In patients with chronic low back pain, reflex inhibition induced by pain leads to atrophy of the back muscles and stiffness of the ligaments and joints. Patients reduce their activities due to pain and stiffness, which results in muscle weakness and strain. These eventually aggravate the pain in a vicious cycle [25
]. A review for the European Guidelines for Prevention of low back pain indicated that core stabilization exercises and traditional lumbar spine exercises are equally effective in the prevention of low back pain because both types strengthen important core muscles of the spine [26
]. These reasons help us to understand the usefulness of physical exercise in preventing low back pain. Although majority of studies have found that physical exercises are useful in preventing low back pain, a study has found that there is a non-significant lower risk of development of lumbar disc disease in men who are involved with high levels of body building and strength training exercises [27
A positive family history of low back pain had a significant positive association with low back pain (P<0.001). People with a family history of low back pain had a sixteen times (OR = 16.2, Table 2) greater chance of developing low back pain compared to people without a family history of low back pain. Research studies have shown that heredity play a significant role with regard to disc degeneration [16
]. Interleukin 1 (IL 1) is one of the most important cytokines that have been implicated in the process of disc degeneration. Degenerated intervertebral discs showed a ten-fold higher IL-1 receptor gene expression compared to non-degenerate intervertebral discs [16
]. Strong muscles of the spine and abdomen are important in the prevention of development of low back pain [25
]. Muscle fibres have different properties with respect to force, contraction speed, endurance, oxidative/glycolytic capacity etc. Although adult muscle fibres are normally post-mitotic with little turnover of cells, the physiological properties of the pre-existing fibres can be changed in the adult animal upon changes in their usage such as physical exercise. The signal to change is mainly conveyed by alterations in the patterns of nerve-evoked electrical activity, and is to a large extent due to switches in the expression of genes [28
]. Above mentioned studies help us understand the association between heredity and low back pain.
In addition to genetic factors the life style of people too are important with regard to development of low back pain. The members in the same family may follow similar life styles [10
]. One other reason for the significant association between low back pain and positive family history in our study could be recall bias. Patients who suffer from low back pain may remember and report about the family history of low back pain more than patients without a low back pain.
BMI had a significant association with Low back pain (P< 0.001). People with low BMI had a 4 times (OR = 4.2, Table 2) greater chance of developing low back pain compared to people with Normal BMI. People with high BMI had a 2 times (OR = 1.6, Table 2) greater chance of developing low back pain compared to people with normal BMI. Although many studies describe a significant association between low back pain and high BMI only few studies describe a significant association between low BMI and low back pain. The results of certain case-control studies have revealed a positive association between increased body mass index and lumbar disc herniation among men and women [27
]. Lumbar disc herniation is an important cause of low back pain and lumbo sacral radicular pain [27
]. A previous study done on Sri Lankan adult females have demonstrated that being overweight and being underweight are both risk factors for low back pain [21
]. In the present study having a low BMI had a higher chance of developing low back pain compared to people with high BMI. People with Anorexia nervosa have a low body mass index. Osteoporosis is a complication of Anorexia nervosa and is associated with a two to three times increase in vertebral fracture risk [29
].Vertebral compression fractures (VCFs) are an important cause of low back pain [30
]. People with increase in BMI may be having strong muscles and bones compared to people with low BMI and strong muscles and bones are important in preventing low back pain [10
According to the results of this study level of income had a significant association with low back pain (P <0.001). People in high income group had a 3 times (OR = 2.6, Table 2) greater chance of developing low back pain compared to people in low and moderate income groups. People with high level of income may be consuming a high calorie diet and may be less involved in taking part in regular physical activities. Both these factors can contribute to development of obesity. Obesity is associated with the development of low back pain [27
In the present study level of education had a significant association with low back pain (P=0.013). People with low education level have a double the chance (OR = 2.2, Table 2) of getting low back pain compared to people with a higher education level. Asian Indians that have a low educational, occupational and socioeconomic status have a greater prevalence of truncal obesity, low HDL cholesterol, hypertriglyceridemia, smoking or tobacco use and low physical activity [31
]. Taking part in regular physical exercise is useful in the prevention of low back pain [13
] and atherosclerosis of blood vessels which is an important cause of disc degeneration [32
]. According to a study done in Norway higher education level was associated with lower probability of current smoking among majority of male immigrants. Never having smoked was positively associated with education level among Pakistani and Norwegian men [33
]. Education improves physical functioning and self-reported health because it enhances a sense of personal control that encourages and enables a healthy life style such as regular walking, exercising, drinking moderately, avoiding being overweight and smoking [34
]. Education enables people to coalesce health producing behaviors into a coherent life style. It does by enhancing the sense of control over outcomes in one’s own life [34
]. According to Mullahy and Robert (2008) more educated individuals find more time to engage in physical exercise than less educated individuals [35
]. Above studies demonstrate that level of education has a strong association with factors such as regular physical exercise, avoiding being overweight and not smoking. All these factors are useful in the prevention of low back pain. Above description help us to understand the beneficial effect the level of education has on low back pain.
In the present study alcohol consumption had a significant association with low back pain (P= 0.039). People in regular (grade 3) alcohol consumption group had a three times (OR = 3.4, Table 2)) greater chance of developing low back pain compared to people in rarely (grade 1) alcohol consumption group. Increasing frequency and quantity of alcohol use is associated with statistically significant weight gain [36
]. Compared with individuals who never drank, the prevalence of metabolic syndrome was significantly higher in men who consumed two to four drinks/day [36
]. Metabolic syndrome is a disorder with increase abdominal obesity, elevated blood pressure, elevated fasting plasma glucose, high serum triglycerides, and low high-density cholesterol (HDL) levels [36
]. Studies have shown being overweight has a significant association with the lumbar sacral radicular pain [11
] and increase BMI is associated with increase chance of developing lumbar disc disease [27
]. Atherosclerosis is known to cause obstruction to the blood flow and reduce the blood supply to the intervertebral discs. Reduce blood supply is a cause of disc degeneration and disc degeneration is an important cause of low back pain [32
]. These may be some of the reasons for alcohol consumption has a significant association with low back pain.
Our study could not find an association between level of smoking and low back pain. Our study findings are similar to the study findings of Kwon, et al. (2006) with regard to smoking [12
]. However studies done by Shiri, et al. (2007) found a significant association between low back pain and smoking [11
]. These studies have been done on different races and different countries and these may be contributing to the different study findings.
According to our study findings consumption of animal proteins did not have a significant association with low back pain. According to another study done among Sri Lankan males found that reduced intake of animal proteins had a significant association with low back pain [13
]. In the present study majority of study subjects were females. This could be a reason why the study findings in these two studies differ. The studies done to find out an association between low back pain and animal protein intake are very sparse.