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Back disorders (low back pain, cervicobrachial and lumbosacral radicular syndromes) and some related risk factors
Journal of the Neurological Sciences 192 Ž2001. 17–25 www.elsevier.comrlocaterjns
Back disorders žlow back pain, cervicobrachial and lumbosacral radicular syndromes/ and some related risk factors V. Kostova a , M. Koleva b,) a
b
Department of Neurology, Center of Occupational Diseases, Medical UniÕersity, Sofia, Bulgaria Department of Hygiene, Ecology and Occupational Health, Medical UniÕersity, 15 BlÕd. Dimitar NestoroÕ, Sofia 1431, Bulgaria Received 29 September 2000; received in revised form 9 July 2001; accepted 11 July 2001
Abstract The aim of this study was to estimate the prevalence rates of low back pain ŽLBP., cervicobrachial and lumbosacral radicular syndromes ŽCBR and LSRS. in workers from a fertilizer plant and also to analyze the impact of several important work-related and non-occupational risk factors. Subjects of this comprehensive cross-sectional study were 898 workers and employees from the four main departments of the plant. The following complex of methods was applied: neurologic history, complete neurologic status and statistical method. Results. Age is the first risk factor, discussed by authors. The data showed highly significant differences in the prevalence of CBS—16.2% in the risk group vs. 10.0% in the referent group ŽOR 1.73, 95% CI 1.14–2.63.; LBP—25.8% vs. 17.0% ŽOR 1.70, 95% CI 1.21–2.38. and LSRS–16.0% vs. 5.8% ŽOR 3.09, 95% CI 1.89–5.08.. Gender is the second risk factor strongly related to LBP, CBS and LSRS. The prevalence of radicular syndromes is higher for women that for men: OR for CBS is 3.27 and 1.93 for LSRS. There is an interesting trend in the case of combined impact of age and gender among men and women of 40 or under and over 40—the risk, estimated by OR, is higher. In men over 40, overweight, obesity and heaviness of smoking, estimated by duration of smoking and daily cigarette consumption Žmore than 20 years and more than 20 cigarettes per day., increase the risk of developing back disorders ŽBD.. At this stage of the research, there is no proof of the impact of hypercholesterolemia, non-occupational or work-related strain on the development of BD. The authors’ conclusion is that these results may support programs for health promotion and health prevention. q 2001 Elsevier Science B.V. All rights reserved. Keywords: Back disorders; Radicular syndromes; Low back pain; Risk factors; Age; Gender; Obesity; Smoking; Work-related and non-occupational strain
1. Introduction Back pain ŽBP. is an unpleasant and noxious sensation of varying severity localized in the different regions of the back, mostly cervical or lumbar w1x. The simplified etiologicrpathogenetic classification of BP includes myofascial, articular Žincluding degenerative disc changes. and neurogenic. Usually more than one type of pain exists simultaneously in a patient at any given time w2x. BP is a serious problem because of the ever increasing number of cases of low back pain, cervicobrachial or lumbosacral radicular syndrome. These complaints are the conditions most commonly involved in personal injury and disability compensation cases w3x. Back disorders ŽBD. affect people in their active work life and often become chronic w4x. The data show that patients are unable to work or lose their
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Corresponding author. Tel.: q359-2-59-60-37. E-mail address: [email protected] ŽM. Koleva..
jobs. So BP often causes severe emotional, physical, economic and social stress and has a negative impact on the patients and their families w5x. Therefore, BP is associated with high costs, psychosocial and disabling effects. Although BD constitutes an important public health problem, there is a paucity of knowledge about risk factors and causal mechanisms w6,7x. The aim of this study was to estimate the prevalence rates of the cervico-brachial syndrome, low back pain and lumbosacral radicular syndrome in workers from a fertilizer plant and also to analyze the impact of several important work-related and non-occupational risk factors on the prevalence of these neurologic syndromes.
2. Subjects and methods This comprehensive cross-sectional study was carried out in the main departments of a fertilizer plant from 1995 to 1998. Eight hundred ninety-eight workers and employ-
0022-510Xr01r$ - see front matter q 2001 Elsevier Science B.V. All rights reserved. PII: S 0 0 2 2 - 5 1 0 X Ž 0 1 . 0 0 5 8 5 - 8
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V. KostoÕa, M. KoleÕar Journal of the Neurological Sciences 192 (2001) 17–25
Fig. 1. Distribution of the workers according to the main personal data Žage, sex, profession..
ees were examined. The subjects were divided into seven different groups1 Žaccording to their occupation and conditions at their work place. and their basic personal characteristics Žage, gender, occupation, smoking, overweightBMI, etc.., presented in Fig. 1. The information was gathered by means of a selective questionnaire and a complete neurologic examination. The following complex of methods was applied in the examination of the nervous system. Ž1. Neurologic history with an emphasis on questions about back pain and paresthesias—questions focusing on
the history of prior episodes and the current episode of back pain: the onset, duration, location, radiation, quality, intensity, and aggravating factors. Paresthesias around the affected root were common. A history of motor or sensory nerve root irritation was important. The neurologic history also included a structured interview with questions about the premorbid condition of the individual, hisrher living conditions, movement, activities, and life style Žsmoking, alcohol consumption, etc... Ž2. Complete neurologic status test of the cranial nerves; assessment of the motor function: analysis of the active and passive motions, muscle tone, posture, gait, and voluntary strength. The following rating scale was used in order to test the latter: 0 s no movement; 1 s flicker; 2 s able to move with gravidity eliminated; 3 s able to move against gravidity; 4 s able to move against resistance; 5 s normal strength; v v
1 This investigation is part of a 5-year project for the exhaustive study of the health of the workers in the main departments of a mineral fertilizer plant. The project has been supported by the workers’ union for the purposes of developing an effective program for health promotion and prevention.
V. KostoÕa, M. KoleÕar Journal of the Neurological Sciences 192 (2001) 17–25
test of the activity of the exteroceptive and proprioceptive reflexes—possible asymmetries between the two sides Žin our study the most important reflexes to test were the biceps, triceps, patellar and Achilles tendon. and of possible qualitative disturbances of the reflex functions Ži.e. pathological reflexes.; assessment of sensory functions: symmetry and differences in cutaneous dermatomes areas, proximal and distal perception in all four extremities, light touch, pinprick perception, and proprioceptive sensation Žrepeated testing was often done to determine the reliability of a patient’s response.. The testing was conducted at the health center of the fertilizer plant: the subjects were given sufficient time off from work to participate in the examinations. Fifteen persons per day underwent the neurological examination, which was carried out by the same neurologist. Ž3. Statistical method: all the results were statistically systematized at a level of reliability of p - 0.05, by means of the AEpi-InfoB program for assessment of the relative risk and odds ratio. The criteria for cervicobrachial syndrome ŽCBS. were stiffness and neck pain, the latter radiating to one or both arms along the damaged nerve root, limited neck movements, numbness of the hands, spontaneous or provoked paresthesias and pain with radicular distribution; objective symptoms such as dermatomic sensory diminution Žoften impairment of the sense of touch.; depressed biceps or brachioradialis reflexes and weakness and atrophy of the corresponding muscles Žinfrequent in our cases.. The criteria for low back pain ŽLBP. included discomfort Žgrowing with increased activity., limited mobility in the region of the low back, pain of varying intensity—often mild or moderate Ževery day for a week or more during the examination period. —restricted to the low back, without distribution over the extremities. The criteria for lumbosacral radicular syndrome ŽLSRS. were subjective complaints regarding pain in the low back of varying intensity following a radicular distribution in one or both legs Žsometimes the pain is relieved when the patient lies down., loss of lordosis or flattening of the lumbar spine, reduced range of movement and tenderness of paraspinal muscles of the same region, numbness and paresthesias in the region of the affected root, positive signs of Lasseque, Neri, Wassermann, etc., objective symptoms for sensory deficit with radicular distribution, occasional weakness in the leg Žsometimes of the dorsiflexion of the big toe., andror depressed ankle or Achilles reflexes. v
v
3. Results Figs. 1 and 2 represent the distribution of the subjects as a total, by gender–age and professional groups, and according to the some risk factors: smoking, obesity and
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dislipidemia. It can be seen from Fig. 1 that the age and gender groups are homogeneous and comparable. Fig. 2 shows that over the half of all individuals Ž60.2%. were AsmokersB; 68.2% fell into Aoverweight and obesityB categories; and only 13.8% exhibited a level of total cholesterol over 6.2 mmolrl Ž240 mg%.. In order to analyze the impact of age on the occurrence and development of BP syndromes, the subjects of this study were divided into two different age groups: risk group—450 persons aged over 40 and referent group—448 persons aged 40 or under and the results were compared. The data showed considerably higher prevalence rates for the persons over 40 than for those under 40. There were statistically significant differences in the prevalence of CBS—16.2% as compared to 10.0% ŽOR 1.73; 95% CI 1.14–2.63.; LBP—25.8% as compared to 17.0% ŽOR 1.70; 95% CI 1.21–2.38. and for LSRS—16.0% as compared to 5.8% ŽOR 3.09; 95% CI 1.89–5.08. ŽTable. 1.. The gender-based differences in BP syndromes revealed a very interesting aspect of the problem of BD risk factors. Two different groups were studied in this respect: 297 women and 601 men. There was a strong correlation between gender and BD. The prevalence of radicular syndromes was higher for women than for men: for example CBS—22.9% as compared to 8.3% ŽOR 3.27; 95% CI 2.16–4.96. and LSRS—15.5% as compared to 8.6% ŽOR 1.93; 95% CI 1.24–3.02.. The prevalence of LBP in women is also greater than in men, but these differences were not statistically significant ŽOR 1.08; 95% CI 0.93– 3.03.. Back disorders generally revealed an interesting trend when we analyzed the combined impact of age and gender. When dividing the subjects of the study into groups: men and women over 40 Žrisk group., and men and women of 40 or under Žreferent group., the data showed that LBP and other radicular syndromes in men increased significantly with age ŽCBS—11.8% in men over 40, as compared to 4.71% in men of 40 or under; OR 2.72 and 95% CI 1.38–5.42; LBP—25.3% as compared to 16.5%; OR 1.72 and 95% CI 1.13–2.62; LSRS—13.8% as compared to 3.4%; OR 4.60 and 95% CI 2.17–9.99.. In women, this relationship is more prominent only with respect to LSRS —the greater prevalence rates were found in the group of women over 40, when contrasted to women of 40 or under ŽOR 2.18; 95% CI 1.08–4.43.. The women over 40 show higher prevalence rates of CBS and LBP than women of 40 or under, i.e., OR greater than 1.0, but this difference is not statistically significant ŽTable 1.. The impact of obesity on the development of back pain and radicular syndromes was evaluated by means of BMI Žthe ratio of the body mass in kilograms and the square of the height in meters.: overweight was diagnosed when the BMI was over 25.1 kgrm2 . It was established that the prevalence rates of BD were greater and OR was higher than 1.0 among persons with a BMI over 25 kgrm2 than in those with a BMI up to 25 kgrm2 , but there was a
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V. KostoÕa, M. KoleÕar Journal of the Neurological Sciences 192 (2001) 17–25
Fig. 2. Distribution of the workers according to the some risk factors.
statistical significance only with respect to LBP ŽOR 1.46; 95% CI 1.01–2.13.. In general, there were no age or gender differences in back disorders based on BMI, with the exception of men over 40, where the prevalence of LBP was higher than in men of 40 or under Ž28.6% as compared to 12.7%, OR 2.76; 95% CI 1.19–6.63..
Smoking is the risk factor for back problems that have given rise to much controversy. Our study revealed no strong relationship between smoking and back disorders. Two groups were compared: smokers, non-smokers and ex-smokers ŽTable 2.. No significant differences were found in the prevalence of CBS, LBP and LSRS among
Group and main syndrome
Risk group
Ref. group
CBS
LBP
LSRS
Variables
n
n
Prev. risk gr. %
Prev. ref. gr. %
OR
95% CI
Prev. risk gr. %
Prev. ref. gr. %
OR
95% CI
Prev. risk gr. %
Prev. ref. gr. %
OR
95% CI
Age Gender Menrage Womenrage BMI BMIrmen up to 40 BMIrmen over 40 BMIrwomen up to 40 BMIrwomen over 40 Cholesterolemia
450 297 304 146 612 190 241 75 106 126
448 601 297 151 284 107 63 74 40 772
16.2 22.9 11.8 25.3 13.6 5.3 11.6 24.0 25.5 12.7
10.0 8.3 4.71 20.5 12.3 3.7 2.7 17.6 25.0 13.2
1.73 3.27 2.72 1.31 1.12 1.43 0.90 1.48 1.03 0.96
1.14–2.63 2.16–4.96 1.38–5.42 0.74–2.34 0.72–1.74 0.40–5.57 0.37–2.29 0.62–3.55 0.41–2.57 0.52–1.73
25.8 22.2 25.3 26.7 23.4 17.4 28.6 16.0 27.4 24.6
17.0 21.0 16.5 17.9 17.2 14.9 12.7 20.0 25.0 20.8
1.70 1.08 1.72 1.67 1.46 1.20 2.76 0.75 1.13 1.24
1.21–2.38 0.76–1.53 1.13–2.62 0.93–3.03 1.01–2.13 0.60–2.41 1.19–6.63 0.30–1.87 0.46–2.83 0.78–1.97
16.0 15.5 13.8 20.5 11.7 2.6 13.7 13.3 22.6 11.9
5.8 8.6 3.4 10.6 9.1 4.7 14.3 8.1 15.0 10.8
3.09 1.93 4.60 2.18 1.32 0.55 0.95 1.74 1.66 1.12
1.89–5.08 1.24–3.02 2.17–9.99 1.08–4.43 0.81–2.18 0.13–2.26 0.41–2.29 0.54–5.77 0.58–4.99 0.60–2.08
CBS—cervicobrachial syndrome; LBP—low back pain; LSRS—lumbosacral radicular syndrome; OR—odds ratio; CI—confidence interval.
V. KostoÕa, M. KoleÕar Journal of the Neurological Sciences 192 (2001) 17–25
Table 1 Prevalence of CBS, LBP and LSRS in the workers of the fertilizer industry—impact of age, gender, obesity and dislipidemia
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22
Groupsrmain syndromes
Risk group
Ref. group
CBS
Variables
n
n
Prev. risk gr. %
Prev. ref. gr. %
OR
95% CI
Prev. risk gr. %
LBP Prev. ref. gr. %
OR
95% CI
Prev. risk gr. %
LSRS Prev. ref. gr. %
OR
95% CI
Smoking a Smoking durationb Smoking duration over 20 years Žmen up to 40. Smoking duration over 20 years Žmen over 40. Smoking duration over 20 years Žwomen up to 40. Smoking duration over 20 years Žwomen up to 40. Daily cigarettes consumption above 20 d Daily cigarettes consumptionr men up to 40 Physical work-related overuse Physical non-occupational strain
539 113 5
356 755 281
10.6 14.2 NS
17.1 13.0 NS
0.57 1.11 NS c
0.38–0.86 0.60–2.01 NS
20.0 24.8 40.0
23.3 20.9 16.0
0.82 1.24 3.59
0.59–1.15 0.76–2.02 0.40–26.70
8.9 18.6 NS
14.0 9.9 NS
0.60 2.07 NS c
0.38–0.93 1.17–3.62 NS
98
192
13.3
11.0
1.25
0.56–2.76
22.4
27.1
0.78
0.40–1.43
19.4
10.9
1.96
0.96–4.05
2
147
NS
NS
NS c
NS
50.0
16.8
4.65
0–17.7
NS
NS
NS c
NS
8
135
37.5
25.2
1.78
0.32–9.21
37.5
25.9
1.71
0.31–8.85
25.0
20.7
1.27
0.17–7.59
75
811
8.0
13.6
0.55
0.21–1.37
18.7
21.7
0.83
0.43–1.57
5.3
11.6
0.43
0.13–1.26
27
265
14.8
3.4
4.95
1.17–19.32
17.4
20.4
0.85
0.24–2.77
NS
NS
NS c
NS
279 588
613 304
12.2 11.2
13.5 16.8
0.89 0.63
0.57–1.39 0.41–0.95
22.9 22.1
20.4 19.4
1.16 1.18
0.81–1.66 0.82–1.69
8.6 11.4
11.9 9.9
0.70 1.17
0.42–1.16 0.73–1.90
CBS—cervicobrachial syndrome; LBP—low back pain; LSRS—lumbosacral radicular syndrome; OR—odds ratio; CI—confidence interval. a Referent group includes non-smokers and ex-smokers. b Risk group includes persons who smoke over 20 years, referent group—all the rest. c NS—the prevalence of the risk group is zero. d Risk group includes persons who smoke above 20 cigarettes daily, referent group – all the rest.
V. KostoÕa, M. KoleÕar Journal of the Neurological Sciences 192 (2001) 17–25
Table 2 Prevalence of CBS, LBP and LSRS by smoking, work-related and non-occupational physical strain
V. KostoÕa, M. KoleÕar Journal of the Neurological Sciences 192 (2001) 17–25
members of the two groups. Odds ratios significantly higher than 1.0 were found only as regards the prevalence rate of following radicular syndromes: v
v
LSRS among persons who have smoked for over 20 years Ž18.6%. when contrasted to that in persons who have smoked for less than 20 years Ž9.9%. —OR 2.07 and 95% CI 1.17–3.62; CBS in men of 40 or under who are heavy smokers Žabove 20 cigarettes daily. —14.8%, as compared to 3.4% in men who do not smoke as heavily Žless than 20 cigarettes daily., OR 4.95 and 95% CI 1.17–19.32.
Other risk factors for BP were also examined—hypercholesterolemia, occupational strain, and non-occupational oÕeruse. Several distinct groups emerge on the basis of these three risk factors: 162 subjects with hypercholesterolemia—total cholesterol above 6.2 mmolrl compared to the referent group Ž n s 772. —total cholesterol under 6.2 mmolrl ŽFig. 2.; risk group Žworkers with work-related overuse.: 279 workers exposed to moderately strenuous tasks at the work place Žrepair staff, loaders, transport equipment machine operators, pump machine operators. and 613 subjects as referents Žwho were not exposed to repetitive motion, overexertion, heavy physical work, etc., in their jobs: operators, compressor operators, laboratory assistants, administrators. ŽTable 2.; risk group—588 subjects who have undergone nonoccupational strain Žperiodically, i.e., 5–6 h daily on the weekend they do physically strenuous work. and referent group—304 persons, not exposed to any non-occupational physical exertion ŽTable 2.. The prevalence rates of CBS, LBP, and LSRS throughout the different groups mentioned above varied considerably but none of these data showed any significant odds ratios or revealed any clear trend as to the importance of hypercholesterolemia, work-related or non-occupational strain as risk factors for BP and BD. v
v
v
4. Discussion The present study has clearly shown that certain factors like age and gender are strongly connected with low back pain, cervicobrachial and lumbosacral radicular syndrome. Other factors, such as overweight and smoking under certain circumstances, are also related to the occurrence of BD, where as there is no proof of the impact of hypercholesterolemia, non-occupational or work-related strain on the development of back pain syndromes. Many factors Že.g., mechanical and various individual causes. contribute to the development of back pain syndromes w8–13x. A strong correlation has been found between age, gender and the prevalence of back disorders. CBS, LBP and
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LSRS are more common among persons over 40 and men show high prevalence rates of radicular syndromes. Many authors argue that the occurrence and development of back disorders increase with age w12–15x. Most studies demonstrate a higher rate of back disorders in the period up to about the fifth w16x or sixth decade of life w13x. Our finding that age constitutes a risk factor for BD coincide with the above claims, although our data shows a lower range for development of BPs Ž40 years. than other authors’. Some prospective studies have, however, revealed that there is no distinct relation to age w17,18x. The impact of gender on the development of back disorders has also been widely researched, more often regarding LBP, rarely regarding CBS or LSRS w14,15x. Most studies show a higher rate of injury for men, but when the strain on the job is considered, the gender difference disappears w16x. Past the age of forty, the risk for women increases much faster than for men Žperhaps related to osteoporosis, obesity, etc... Our results support the thesis of some authors that back disorders are related to gender and that men are probably more susceptible to developing BP syndromes than women w19x. With age, the risk of back disorders increases again much more obviously for men than for women: the prevalence rates of all back pain syndromes are significantly higher in men over 40 than in those of 40 or under. The case of LSRS in women constitutes an exception. Perhaps other factors play a part here: for example, the wearing out of different back structures in the lumbar region due to gravidity loading, endocrine disbalance and osteoporosis typical for the climacteric period, etc. Analyzing the relative importance of obesity as a risk factor for BP syndromes by means of calculating the BMI in different groups, we found a statistically significant link between obesity and LBP, but the relationship between radicular back disorders and obesity is not significant. Obesity and back disorders in men and women over 40 exhibited a similar trend. In fact, the risk for developing LBP and back problems due to obesity may be even more significant in older men who tend to gain weight as they age. A positive relation between excess body weight and risk for back disorders was shown in most studies w12,17,20,21x, but the authors revealed that there is no distinct dependence on obesity w9x. Many authors suggest that smoking in particular seems to increase the risk of LBP, disk disease and LSRS w17,19,22,23x. Some physiologic studies have shown that smoking impairs the blood supply to the vertebral endplate and thereby decreases the nutrition of the intervertebral disk. In the present study, we found no relationship between smoking and BP syndromes. An exception can be identified when analyzing the link between the heaviness of smoking and back disorders. A statistically significant correlation has been found between the duration of smoking and LSRS. It is important to note here that this data assessment suffers due to the incomplete control over
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V. KostoÕa, M. KoleÕar Journal of the Neurological Sciences 192 (2001) 17–25
some additional factors Žespecially age.. CBS and LBP also show higher prevalence rates for smokers with long smoking practice, but there is no statistical significance to this data. Despite the fragmentary nature of the results regarding smoking, our data corroborate to some extent the argument that smoking Žespecially in cases with long smoking practice, i.e., more than 20 years. may be related to the occurrence of BD. The most widely discussed risk factors for BD include strain and overuse at work w24–32x or in the subject’s non-occupational lifestyle w9,12x. Many work-related factors, such as heavy physical work, prolonged sitting Žstatic work posture., lifting and forceful movements, repetitive bending and whole-body vibration, have been reported to be of importance in the development of BD w12,33–37x. In contrast to these findings, our results do not demonstrate any significant connection between work-related strain and BD. This may be due partially to the fact that the workers in the exposure group Žwith work related overuse. were repair staff, loaders, transport equipment machine operators, pump machine operators, whose occupational physical strain is mild. The AclassicalB occupational factors w15x for the development of BP syndromes such as constrained working postures w38x and back-straining tasks, heavy physical work and repetitive manual handling, pulling, pushing, etc., are not part of the physical activities required for their jobs. At this stage of our research, there is also no clear proof of the impact of non-occupational overuse on the development of back disorders. There is probably another explanation of this fact: occasional and irregular gardening and other non-occupational physical tasks carried out mostly on weekends. This overuse is followed by periods of rest from physical labor, which permits the AtiredB back structures to recover. In other cases, the degree of non-occupational physical activity is insignificant and cannot cause damage to the back structures and nerve roots. The present study support the view that some individual factors like age and gender are strongly connected with back disorders, whereas other causes Žoverweight, smoking. demonstrate varied results. These results may support programs to prevent the development of BD: for example, activities to stabilize the back structures and measures against osteoporosis, especially in jobs involving heavy physical labor, prevention of obesity, smoking control and cessation programs, etc. Nonetheless, our study has not identified the nature of the relationship between hypercholesterolemia, non-occupational or work related overuse and back disorders, and we consider it necessary to pursue this line of research in the future. References w1x Belkin S. Back pain. In: Aronoff GM, editor. Evaluation and Treatment of Chronic Pain. Baltimore: Williams & Wilkins; 1992. p. 248–59.
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w28x w29x w30x
w31x w32x w33x
shoulder–neck diseases in different occupational groups. Br J Ind Med 1987;44:602–10. Hildebrandt VH. Back pain in the working population: prevalence rates in Dutch trades and professions. Ergonomics 1995;38:1283–98. Masset D, Malchaire J. Low back pain. Epidemiologic aspects and work-related factors in the steel industry. Spine 1994;19:143–6. Serratos-Perez JN, Mendiola-Anda C. Musculoskeletal disorders among male sewing machine operators in shoemaking. Ergonomics 1993;36:793–800. Waris P. Occupational cervicobrachial syndromes. Scand J Work, Environ Health 1979;6:3–13. Yu T-S, Roht LH, Wise RA, et al. Low-back pain in industry: an old problem revised. J Occup Med 1984;26:517–24. Bonger PM, Boshuizen HC, Hulshof CTJ, et al. Back disorders in crane operators exposed to whole-body vibration. Int Arch Occup Environ Health 1988;60:129–37.
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w34x Boshuizen HC, Hulshof CTJ, Bonger PM. Long-term sick leave and disability pensioning due to back disorders of tractor drivers exposed to whole-body vibration. Int Arch Occup Environ Health 1990; 62:117–22. w35x Dimberg L, Olafsson A, Stefansson E, et al. The correlation between work environment and the occurrence of cervico-brachial symptoms. J Occup Med 1989;31:447–53. w36x Dupuis H, Zerlett G. Whole-body vibration and disorders of the spine. Int Arch Occup Environ Health 1987;59:323–36. w37x Hagberg M. Occupational musculoskeletal stress and disorders of the neck and shoulder: A review of possible pathophysiology. Int Arch Occup Environ Health 1984;53:269–78. w38x Knibbe JJ, Friele RD. Prevalence of back pain and characteristics of the physical workload of community nurses. Ergonomics 1996;39: 186–98.
Back disorders žlow back pain, cervicobrachial and lumbosacral radicular syndromes/ and some related risk factors V. Kostova a , M. Koleva b,) a
b
Department of Neurology, Center of Occupational Diseases, Medical UniÕersity, Sofia, Bulgaria Department of Hygiene, Ecology and Occupational Health, Medical UniÕersity, 15 BlÕd. Dimitar NestoroÕ, Sofia 1431, Bulgaria Received 29 September 2000; received in revised form 9 July 2001; accepted 11 July 2001
Abstract The aim of this study was to estimate the prevalence rates of low back pain ŽLBP., cervicobrachial and lumbosacral radicular syndromes ŽCBR and LSRS. in workers from a fertilizer plant and also to analyze the impact of several important work-related and non-occupational risk factors. Subjects of this comprehensive cross-sectional study were 898 workers and employees from the four main departments of the plant. The following complex of methods was applied: neurologic history, complete neurologic status and statistical method. Results. Age is the first risk factor, discussed by authors. The data showed highly significant differences in the prevalence of CBS—16.2% in the risk group vs. 10.0% in the referent group ŽOR 1.73, 95% CI 1.14–2.63.; LBP—25.8% vs. 17.0% ŽOR 1.70, 95% CI 1.21–2.38. and LSRS–16.0% vs. 5.8% ŽOR 3.09, 95% CI 1.89–5.08.. Gender is the second risk factor strongly related to LBP, CBS and LSRS. The prevalence of radicular syndromes is higher for women that for men: OR for CBS is 3.27 and 1.93 for LSRS. There is an interesting trend in the case of combined impact of age and gender among men and women of 40 or under and over 40—the risk, estimated by OR, is higher. In men over 40, overweight, obesity and heaviness of smoking, estimated by duration of smoking and daily cigarette consumption Žmore than 20 years and more than 20 cigarettes per day., increase the risk of developing back disorders ŽBD.. At this stage of the research, there is no proof of the impact of hypercholesterolemia, non-occupational or work-related strain on the development of BD. The authors’ conclusion is that these results may support programs for health promotion and health prevention. q 2001 Elsevier Science B.V. All rights reserved. Keywords: Back disorders; Radicular syndromes; Low back pain; Risk factors; Age; Gender; Obesity; Smoking; Work-related and non-occupational strain
1. Introduction Back pain ŽBP. is an unpleasant and noxious sensation of varying severity localized in the different regions of the back, mostly cervical or lumbar w1x. The simplified etiologicrpathogenetic classification of BP includes myofascial, articular Žincluding degenerative disc changes. and neurogenic. Usually more than one type of pain exists simultaneously in a patient at any given time w2x. BP is a serious problem because of the ever increasing number of cases of low back pain, cervicobrachial or lumbosacral radicular syndrome. These complaints are the conditions most commonly involved in personal injury and disability compensation cases w3x. Back disorders ŽBD. affect people in their active work life and often become chronic w4x. The data show that patients are unable to work or lose their
)
Corresponding author. Tel.: q359-2-59-60-37. E-mail address: [email protected] ŽM. Koleva..
jobs. So BP often causes severe emotional, physical, economic and social stress and has a negative impact on the patients and their families w5x. Therefore, BP is associated with high costs, psychosocial and disabling effects. Although BD constitutes an important public health problem, there is a paucity of knowledge about risk factors and causal mechanisms w6,7x. The aim of this study was to estimate the prevalence rates of the cervico-brachial syndrome, low back pain and lumbosacral radicular syndrome in workers from a fertilizer plant and also to analyze the impact of several important work-related and non-occupational risk factors on the prevalence of these neurologic syndromes.
2. Subjects and methods This comprehensive cross-sectional study was carried out in the main departments of a fertilizer plant from 1995 to 1998. Eight hundred ninety-eight workers and employ-
0022-510Xr01r$ - see front matter q 2001 Elsevier Science B.V. All rights reserved. PII: S 0 0 2 2 - 5 1 0 X Ž 0 1 . 0 0 5 8 5 - 8
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V. KostoÕa, M. KoleÕar Journal of the Neurological Sciences 192 (2001) 17–25
Fig. 1. Distribution of the workers according to the main personal data Žage, sex, profession..
ees were examined. The subjects were divided into seven different groups1 Žaccording to their occupation and conditions at their work place. and their basic personal characteristics Žage, gender, occupation, smoking, overweightBMI, etc.., presented in Fig. 1. The information was gathered by means of a selective questionnaire and a complete neurologic examination. The following complex of methods was applied in the examination of the nervous system. Ž1. Neurologic history with an emphasis on questions about back pain and paresthesias—questions focusing on
the history of prior episodes and the current episode of back pain: the onset, duration, location, radiation, quality, intensity, and aggravating factors. Paresthesias around the affected root were common. A history of motor or sensory nerve root irritation was important. The neurologic history also included a structured interview with questions about the premorbid condition of the individual, hisrher living conditions, movement, activities, and life style Žsmoking, alcohol consumption, etc... Ž2. Complete neurologic status test of the cranial nerves; assessment of the motor function: analysis of the active and passive motions, muscle tone, posture, gait, and voluntary strength. The following rating scale was used in order to test the latter: 0 s no movement; 1 s flicker; 2 s able to move with gravidity eliminated; 3 s able to move against gravidity; 4 s able to move against resistance; 5 s normal strength; v v
1 This investigation is part of a 5-year project for the exhaustive study of the health of the workers in the main departments of a mineral fertilizer plant. The project has been supported by the workers’ union for the purposes of developing an effective program for health promotion and prevention.
V. KostoÕa, M. KoleÕar Journal of the Neurological Sciences 192 (2001) 17–25
test of the activity of the exteroceptive and proprioceptive reflexes—possible asymmetries between the two sides Žin our study the most important reflexes to test were the biceps, triceps, patellar and Achilles tendon. and of possible qualitative disturbances of the reflex functions Ži.e. pathological reflexes.; assessment of sensory functions: symmetry and differences in cutaneous dermatomes areas, proximal and distal perception in all four extremities, light touch, pinprick perception, and proprioceptive sensation Žrepeated testing was often done to determine the reliability of a patient’s response.. The testing was conducted at the health center of the fertilizer plant: the subjects were given sufficient time off from work to participate in the examinations. Fifteen persons per day underwent the neurological examination, which was carried out by the same neurologist. Ž3. Statistical method: all the results were statistically systematized at a level of reliability of p - 0.05, by means of the AEpi-InfoB program for assessment of the relative risk and odds ratio. The criteria for cervicobrachial syndrome ŽCBS. were stiffness and neck pain, the latter radiating to one or both arms along the damaged nerve root, limited neck movements, numbness of the hands, spontaneous or provoked paresthesias and pain with radicular distribution; objective symptoms such as dermatomic sensory diminution Žoften impairment of the sense of touch.; depressed biceps or brachioradialis reflexes and weakness and atrophy of the corresponding muscles Žinfrequent in our cases.. The criteria for low back pain ŽLBP. included discomfort Žgrowing with increased activity., limited mobility in the region of the low back, pain of varying intensity—often mild or moderate Ževery day for a week or more during the examination period. —restricted to the low back, without distribution over the extremities. The criteria for lumbosacral radicular syndrome ŽLSRS. were subjective complaints regarding pain in the low back of varying intensity following a radicular distribution in one or both legs Žsometimes the pain is relieved when the patient lies down., loss of lordosis or flattening of the lumbar spine, reduced range of movement and tenderness of paraspinal muscles of the same region, numbness and paresthesias in the region of the affected root, positive signs of Lasseque, Neri, Wassermann, etc., objective symptoms for sensory deficit with radicular distribution, occasional weakness in the leg Žsometimes of the dorsiflexion of the big toe., andror depressed ankle or Achilles reflexes. v
v
3. Results Figs. 1 and 2 represent the distribution of the subjects as a total, by gender–age and professional groups, and according to the some risk factors: smoking, obesity and
19
dislipidemia. It can be seen from Fig. 1 that the age and gender groups are homogeneous and comparable. Fig. 2 shows that over the half of all individuals Ž60.2%. were AsmokersB; 68.2% fell into Aoverweight and obesityB categories; and only 13.8% exhibited a level of total cholesterol over 6.2 mmolrl Ž240 mg%.. In order to analyze the impact of age on the occurrence and development of BP syndromes, the subjects of this study were divided into two different age groups: risk group—450 persons aged over 40 and referent group—448 persons aged 40 or under and the results were compared. The data showed considerably higher prevalence rates for the persons over 40 than for those under 40. There were statistically significant differences in the prevalence of CBS—16.2% as compared to 10.0% ŽOR 1.73; 95% CI 1.14–2.63.; LBP—25.8% as compared to 17.0% ŽOR 1.70; 95% CI 1.21–2.38. and for LSRS—16.0% as compared to 5.8% ŽOR 3.09; 95% CI 1.89–5.08. ŽTable. 1.. The gender-based differences in BP syndromes revealed a very interesting aspect of the problem of BD risk factors. Two different groups were studied in this respect: 297 women and 601 men. There was a strong correlation between gender and BD. The prevalence of radicular syndromes was higher for women than for men: for example CBS—22.9% as compared to 8.3% ŽOR 3.27; 95% CI 2.16–4.96. and LSRS—15.5% as compared to 8.6% ŽOR 1.93; 95% CI 1.24–3.02.. The prevalence of LBP in women is also greater than in men, but these differences were not statistically significant ŽOR 1.08; 95% CI 0.93– 3.03.. Back disorders generally revealed an interesting trend when we analyzed the combined impact of age and gender. When dividing the subjects of the study into groups: men and women over 40 Žrisk group., and men and women of 40 or under Žreferent group., the data showed that LBP and other radicular syndromes in men increased significantly with age ŽCBS—11.8% in men over 40, as compared to 4.71% in men of 40 or under; OR 2.72 and 95% CI 1.38–5.42; LBP—25.3% as compared to 16.5%; OR 1.72 and 95% CI 1.13–2.62; LSRS—13.8% as compared to 3.4%; OR 4.60 and 95% CI 2.17–9.99.. In women, this relationship is more prominent only with respect to LSRS —the greater prevalence rates were found in the group of women over 40, when contrasted to women of 40 or under ŽOR 2.18; 95% CI 1.08–4.43.. The women over 40 show higher prevalence rates of CBS and LBP than women of 40 or under, i.e., OR greater than 1.0, but this difference is not statistically significant ŽTable 1.. The impact of obesity on the development of back pain and radicular syndromes was evaluated by means of BMI Žthe ratio of the body mass in kilograms and the square of the height in meters.: overweight was diagnosed when the BMI was over 25.1 kgrm2 . It was established that the prevalence rates of BD were greater and OR was higher than 1.0 among persons with a BMI over 25 kgrm2 than in those with a BMI up to 25 kgrm2 , but there was a
20
V. KostoÕa, M. KoleÕar Journal of the Neurological Sciences 192 (2001) 17–25
Fig. 2. Distribution of the workers according to the some risk factors.
statistical significance only with respect to LBP ŽOR 1.46; 95% CI 1.01–2.13.. In general, there were no age or gender differences in back disorders based on BMI, with the exception of men over 40, where the prevalence of LBP was higher than in men of 40 or under Ž28.6% as compared to 12.7%, OR 2.76; 95% CI 1.19–6.63..
Smoking is the risk factor for back problems that have given rise to much controversy. Our study revealed no strong relationship between smoking and back disorders. Two groups were compared: smokers, non-smokers and ex-smokers ŽTable 2.. No significant differences were found in the prevalence of CBS, LBP and LSRS among
Group and main syndrome
Risk group
Ref. group
CBS
LBP
LSRS
Variables
n
n
Prev. risk gr. %
Prev. ref. gr. %
OR
95% CI
Prev. risk gr. %
Prev. ref. gr. %
OR
95% CI
Prev. risk gr. %
Prev. ref. gr. %
OR
95% CI
Age Gender Menrage Womenrage BMI BMIrmen up to 40 BMIrmen over 40 BMIrwomen up to 40 BMIrwomen over 40 Cholesterolemia
450 297 304 146 612 190 241 75 106 126
448 601 297 151 284 107 63 74 40 772
16.2 22.9 11.8 25.3 13.6 5.3 11.6 24.0 25.5 12.7
10.0 8.3 4.71 20.5 12.3 3.7 2.7 17.6 25.0 13.2
1.73 3.27 2.72 1.31 1.12 1.43 0.90 1.48 1.03 0.96
1.14–2.63 2.16–4.96 1.38–5.42 0.74–2.34 0.72–1.74 0.40–5.57 0.37–2.29 0.62–3.55 0.41–2.57 0.52–1.73
25.8 22.2 25.3 26.7 23.4 17.4 28.6 16.0 27.4 24.6
17.0 21.0 16.5 17.9 17.2 14.9 12.7 20.0 25.0 20.8
1.70 1.08 1.72 1.67 1.46 1.20 2.76 0.75 1.13 1.24
1.21–2.38 0.76–1.53 1.13–2.62 0.93–3.03 1.01–2.13 0.60–2.41 1.19–6.63 0.30–1.87 0.46–2.83 0.78–1.97
16.0 15.5 13.8 20.5 11.7 2.6 13.7 13.3 22.6 11.9
5.8 8.6 3.4 10.6 9.1 4.7 14.3 8.1 15.0 10.8
3.09 1.93 4.60 2.18 1.32 0.55 0.95 1.74 1.66 1.12
1.89–5.08 1.24–3.02 2.17–9.99 1.08–4.43 0.81–2.18 0.13–2.26 0.41–2.29 0.54–5.77 0.58–4.99 0.60–2.08
CBS—cervicobrachial syndrome; LBP—low back pain; LSRS—lumbosacral radicular syndrome; OR—odds ratio; CI—confidence interval.
V. KostoÕa, M. KoleÕar Journal of the Neurological Sciences 192 (2001) 17–25
Table 1 Prevalence of CBS, LBP and LSRS in the workers of the fertilizer industry—impact of age, gender, obesity and dislipidemia
21
22
Groupsrmain syndromes
Risk group
Ref. group
CBS
Variables
n
n
Prev. risk gr. %
Prev. ref. gr. %
OR
95% CI
Prev. risk gr. %
LBP Prev. ref. gr. %
OR
95% CI
Prev. risk gr. %
LSRS Prev. ref. gr. %
OR
95% CI
Smoking a Smoking durationb Smoking duration over 20 years Žmen up to 40. Smoking duration over 20 years Žmen over 40. Smoking duration over 20 years Žwomen up to 40. Smoking duration over 20 years Žwomen up to 40. Daily cigarettes consumption above 20 d Daily cigarettes consumptionr men up to 40 Physical work-related overuse Physical non-occupational strain
539 113 5
356 755 281
10.6 14.2 NS
17.1 13.0 NS
0.57 1.11 NS c
0.38–0.86 0.60–2.01 NS
20.0 24.8 40.0
23.3 20.9 16.0
0.82 1.24 3.59
0.59–1.15 0.76–2.02 0.40–26.70
8.9 18.6 NS
14.0 9.9 NS
0.60 2.07 NS c
0.38–0.93 1.17–3.62 NS
98
192
13.3
11.0
1.25
0.56–2.76
22.4
27.1
0.78
0.40–1.43
19.4
10.9
1.96
0.96–4.05
2
147
NS
NS
NS c
NS
50.0
16.8
4.65
0–17.7
NS
NS
NS c
NS
8
135
37.5
25.2
1.78
0.32–9.21
37.5
25.9
1.71
0.31–8.85
25.0
20.7
1.27
0.17–7.59
75
811
8.0
13.6
0.55
0.21–1.37
18.7
21.7
0.83
0.43–1.57
5.3
11.6
0.43
0.13–1.26
27
265
14.8
3.4
4.95
1.17–19.32
17.4
20.4
0.85
0.24–2.77
NS
NS
NS c
NS
279 588
613 304
12.2 11.2
13.5 16.8
0.89 0.63
0.57–1.39 0.41–0.95
22.9 22.1
20.4 19.4
1.16 1.18
0.81–1.66 0.82–1.69
8.6 11.4
11.9 9.9
0.70 1.17
0.42–1.16 0.73–1.90
CBS—cervicobrachial syndrome; LBP—low back pain; LSRS—lumbosacral radicular syndrome; OR—odds ratio; CI—confidence interval. a Referent group includes non-smokers and ex-smokers. b Risk group includes persons who smoke over 20 years, referent group—all the rest. c NS—the prevalence of the risk group is zero. d Risk group includes persons who smoke above 20 cigarettes daily, referent group – all the rest.
V. KostoÕa, M. KoleÕar Journal of the Neurological Sciences 192 (2001) 17–25
Table 2 Prevalence of CBS, LBP and LSRS by smoking, work-related and non-occupational physical strain
V. KostoÕa, M. KoleÕar Journal of the Neurological Sciences 192 (2001) 17–25
members of the two groups. Odds ratios significantly higher than 1.0 were found only as regards the prevalence rate of following radicular syndromes: v
v
LSRS among persons who have smoked for over 20 years Ž18.6%. when contrasted to that in persons who have smoked for less than 20 years Ž9.9%. —OR 2.07 and 95% CI 1.17–3.62; CBS in men of 40 or under who are heavy smokers Žabove 20 cigarettes daily. —14.8%, as compared to 3.4% in men who do not smoke as heavily Žless than 20 cigarettes daily., OR 4.95 and 95% CI 1.17–19.32.
Other risk factors for BP were also examined—hypercholesterolemia, occupational strain, and non-occupational oÕeruse. Several distinct groups emerge on the basis of these three risk factors: 162 subjects with hypercholesterolemia—total cholesterol above 6.2 mmolrl compared to the referent group Ž n s 772. —total cholesterol under 6.2 mmolrl ŽFig. 2.; risk group Žworkers with work-related overuse.: 279 workers exposed to moderately strenuous tasks at the work place Žrepair staff, loaders, transport equipment machine operators, pump machine operators. and 613 subjects as referents Žwho were not exposed to repetitive motion, overexertion, heavy physical work, etc., in their jobs: operators, compressor operators, laboratory assistants, administrators. ŽTable 2.; risk group—588 subjects who have undergone nonoccupational strain Žperiodically, i.e., 5–6 h daily on the weekend they do physically strenuous work. and referent group—304 persons, not exposed to any non-occupational physical exertion ŽTable 2.. The prevalence rates of CBS, LBP, and LSRS throughout the different groups mentioned above varied considerably but none of these data showed any significant odds ratios or revealed any clear trend as to the importance of hypercholesterolemia, work-related or non-occupational strain as risk factors for BP and BD. v
v
v
4. Discussion The present study has clearly shown that certain factors like age and gender are strongly connected with low back pain, cervicobrachial and lumbosacral radicular syndrome. Other factors, such as overweight and smoking under certain circumstances, are also related to the occurrence of BD, where as there is no proof of the impact of hypercholesterolemia, non-occupational or work-related strain on the development of back pain syndromes. Many factors Že.g., mechanical and various individual causes. contribute to the development of back pain syndromes w8–13x. A strong correlation has been found between age, gender and the prevalence of back disorders. CBS, LBP and
23
LSRS are more common among persons over 40 and men show high prevalence rates of radicular syndromes. Many authors argue that the occurrence and development of back disorders increase with age w12–15x. Most studies demonstrate a higher rate of back disorders in the period up to about the fifth w16x or sixth decade of life w13x. Our finding that age constitutes a risk factor for BD coincide with the above claims, although our data shows a lower range for development of BPs Ž40 years. than other authors’. Some prospective studies have, however, revealed that there is no distinct relation to age w17,18x. The impact of gender on the development of back disorders has also been widely researched, more often regarding LBP, rarely regarding CBS or LSRS w14,15x. Most studies show a higher rate of injury for men, but when the strain on the job is considered, the gender difference disappears w16x. Past the age of forty, the risk for women increases much faster than for men Žperhaps related to osteoporosis, obesity, etc... Our results support the thesis of some authors that back disorders are related to gender and that men are probably more susceptible to developing BP syndromes than women w19x. With age, the risk of back disorders increases again much more obviously for men than for women: the prevalence rates of all back pain syndromes are significantly higher in men over 40 than in those of 40 or under. The case of LSRS in women constitutes an exception. Perhaps other factors play a part here: for example, the wearing out of different back structures in the lumbar region due to gravidity loading, endocrine disbalance and osteoporosis typical for the climacteric period, etc. Analyzing the relative importance of obesity as a risk factor for BP syndromes by means of calculating the BMI in different groups, we found a statistically significant link between obesity and LBP, but the relationship between radicular back disorders and obesity is not significant. Obesity and back disorders in men and women over 40 exhibited a similar trend. In fact, the risk for developing LBP and back problems due to obesity may be even more significant in older men who tend to gain weight as they age. A positive relation between excess body weight and risk for back disorders was shown in most studies w12,17,20,21x, but the authors revealed that there is no distinct dependence on obesity w9x. Many authors suggest that smoking in particular seems to increase the risk of LBP, disk disease and LSRS w17,19,22,23x. Some physiologic studies have shown that smoking impairs the blood supply to the vertebral endplate and thereby decreases the nutrition of the intervertebral disk. In the present study, we found no relationship between smoking and BP syndromes. An exception can be identified when analyzing the link between the heaviness of smoking and back disorders. A statistically significant correlation has been found between the duration of smoking and LSRS. It is important to note here that this data assessment suffers due to the incomplete control over
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some additional factors Žespecially age.. CBS and LBP also show higher prevalence rates for smokers with long smoking practice, but there is no statistical significance to this data. Despite the fragmentary nature of the results regarding smoking, our data corroborate to some extent the argument that smoking Žespecially in cases with long smoking practice, i.e., more than 20 years. may be related to the occurrence of BD. The most widely discussed risk factors for BD include strain and overuse at work w24–32x or in the subject’s non-occupational lifestyle w9,12x. Many work-related factors, such as heavy physical work, prolonged sitting Žstatic work posture., lifting and forceful movements, repetitive bending and whole-body vibration, have been reported to be of importance in the development of BD w12,33–37x. In contrast to these findings, our results do not demonstrate any significant connection between work-related strain and BD. This may be due partially to the fact that the workers in the exposure group Žwith work related overuse. were repair staff, loaders, transport equipment machine operators, pump machine operators, whose occupational physical strain is mild. The AclassicalB occupational factors w15x for the development of BP syndromes such as constrained working postures w38x and back-straining tasks, heavy physical work and repetitive manual handling, pulling, pushing, etc., are not part of the physical activities required for their jobs. At this stage of our research, there is also no clear proof of the impact of non-occupational overuse on the development of back disorders. There is probably another explanation of this fact: occasional and irregular gardening and other non-occupational physical tasks carried out mostly on weekends. This overuse is followed by periods of rest from physical labor, which permits the AtiredB back structures to recover. In other cases, the degree of non-occupational physical activity is insignificant and cannot cause damage to the back structures and nerve roots. The present study support the view that some individual factors like age and gender are strongly connected with back disorders, whereas other causes Žoverweight, smoking. demonstrate varied results. These results may support programs to prevent the development of BD: for example, activities to stabilize the back structures and measures against osteoporosis, especially in jobs involving heavy physical labor, prevention of obesity, smoking control and cessation programs, etc. Nonetheless, our study has not identified the nature of the relationship between hypercholesterolemia, non-occupational or work related overuse and back disorders, and we consider it necessary to pursue this line of research in the future. References w1x Belkin S. Back pain. In: Aronoff GM, editor. Evaluation and Treatment of Chronic Pain. Baltimore: Williams & Wilkins; 1992. p. 248–59.
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