Prevalence and Factors Associated with Chronic Low Back Pain in the Mining Sector in Burkina Faso ()
1. Introduction
A public health pathology, low back pain is the leading cause of work-related disability before the age of 45 [1]. It affects 60% - 70% of workers in France [2]. According to France’s Haute Autorité de Santé (HAS), chronic low-back pain is defined as pain in the lumbar region related to damage to the intervertebral disc and/or posterior vertebral joints, which has been present for more than three months. Pain may radiate to the buttock, iliac crest or thigh, and only exceptionally extends beyond the knee [3].
It may be accompanied by radicular pain when a spinal nerve root is involved, causing pain in the leg along the spinal nerve, accompanied by numbness and tingling, muscle weakness and loss of reflexes [4].
The prevalence of this pathology remains high in the workplace in Africa and particularly in Burkina Faso. Indeed, among workers at the port handling station in Cotonou, this prevalence was 52.6% in 2017 [5]. It was 68.89% in 2019 among motorcycle cab drivers in Porto-Novo, Benin [6]. In Burkina Faso, its prevalence was 59% among physical education and sports teachers (EPS) in Ouagadougou and 76.5% among traditional loincloth weavers in Ouagadougou [7] [8]. In the workplace, this pathology has a number of consequences both for individual workers and for the company as a whole. In fact, chronic low-back pain is the cause of work stoppages and reduced quality of life for sufferers [9] [10]. What’s more, the costs associated with treating this pathology in the workplace are considerable, amounting to over a billion euros a year in France [1]. There are also indirect costs that are difficult to assess, such as reduced production, recruitment and training of replacements, and the risk of production stoppages.
In the mining sector, as in other sectors, several risk factors are associated with the onset of this pathology in workers. These include manual handling, vibration, awkward working postures and intense physical work. Non-occupational factors are also associated with its occurrence. In a study carried out among Senegalese nursing staff, manual handling was a risk factor for this pathology [11].
To the best of our knowledge, no study has yet been carried out on this pathology in the mining sector in the country, which had 27 industrial mines in 2022, including 24 gold mines [12]; hence the interest of our study, which aims to determine the prevalence and factors associated with chronic low back pain in the mining sector in Burkina Faso.
2. Materials and Methods
2.1. Type and Period of Study
This was a cross-sectional descriptive and analytical study with retrospective collection that took place from August 1, 2021 to March 16, 2022 in a gold mine in Burkina Faso. It included all workers with low back pain at the mine who attended the 2019 annual medical check-up.
2.2. Inclusion Criteria
Workers suffering from low back pain and who had undergone a radiological examination of the lumbar spine were included in the study.
2.3. Non-Inclusion Criteria
Not included in the study were workers with insufficient data from the medical check-up, or workers absent during the study period.
2.4. Sampling
This was a convenience sample of mine workers who attended the 2019 periodic medical check-up and whose clinical records met the inclusion criteria.
2.5. Study Variables
Chronic low-back pain was the study’s dependent variable. The independent variables were: socio-demographic variables (age, gender, marital status) and occupational variables (profession, job position, job seniority).
Mechanical pain is induced pain; it occurs as a result of movement, walking (it is useful to determine the walking perimeter), weight-bearing and weight-bearing. It is pain that calms down with rest. It occurs during the day, mainly at the end of the day (when tired). The intensity of the pain was assessed using the Visual Analogue Scale (VAS). It corresponds to the distance in millimetres between the position of the cursor moved manually by the patient and the “no pain” end of the scale (0 mm), with the other end marked “the worst pain imaginable” (100 mm). The scores obtained from the VAS have a descriptive value for a given individual and make it possible to monitor his or her state of pain. This is the scale most commonly used in our context.
Radicular pain was assessed using the Lasègue sign: in a patient lying supine, flexion of the extended lower limb on the thigh is limited by the pain. If the manoeuvre is performed with the leg bent, mobilisation of the limb is not painful. This sign distinguishes sciatica from joint disorders.
2.6. Data Analysis
For the descriptive study, Microsoft Office software version 2016 with its Word and Excel components was used for analysis and table processing.
The analytical study for the search for associated factors was carried out in two stages using Epi info software version 7.2.4. Fisher’s exact test and Chi2 test were used to calculate p-values as a measure of association with chronic low back pain, as well as 95% confidence intervals at the 5% significance level.
After univariate analysis, all variables associated (independent variables) with chronic low back pain (dependent variable) at a threshold of 20% (p < 0.2) were included in a multivariate logistic regression model. The association between chronic low back pain and each factor was investigated independently of the other factors using multiple logistic regression. In the end, we retained as factors associated with chronic low-back pain those variables whose p values were <0.05 at the end of the multivariate analysis.
2.7. Ethical Considerations
To carry out the study, the agreement of the mining company’s General Manager was obtained.
The anonymity of the questionnaire and the confidentiality of the data collected were respected.
3. Results
3.1. Prevalence of Chronic Low Back Pain
Out of a total of 1200 employees at the mine at the time of the study, 880 took part in the 2019 periodic medical check-up, representing a participation rate of 73.33%. Among the workers who took part in the said visit, 165 had chronic common low-back pain, i.e. a prevalence of 18.75%.
3.2. Socio-Demographic Characteristics of Workers with Low Back Pain
The mean age of workers with low back pain was 37.21 ± 7.5 years, with extremes of 22 and 55 years. The male sex was the most represented in the study, with 156 workers (94.55%), and the sex ratio was 17 men to 1 woman. 66 workers (40%) were uneducated.
The socio-demographic characteristics of workers with low back pain are shown in Table 1.
Table 1. Socio-demographic characteristics of workers with low back pain.
|
Number |
Percentage |
Age |
|
|
≤22 |
1 |
0.61 |
]22 - 32] |
47 |
28.48 |
]32 - 42] |
79 |
47.88 |
]42 - 52] |
34 |
20.61 |
]52 - 55] |
4 |
2.42 |
Gender |
|
|
Male |
156 |
94.55 |
Female |
9 |
5.45
|
Study level |
|
|
Primary |
30 |
18.18 |
Secondary |
45 |
27.27 |
Higher |
24 |
14.55 |
No schooling |
66 |
40 |
3.3. Occupational Characteristics of Workers with Low Back Pain
The majority of workers suffering from low back pain in the study were in the mining department, with a workforce of 67 workers (or 40.61%), followed by the plant department, with 58 workers (35.15%). The machine operator position was the most represented, with 62 workers (37.58%), followed by plant operators, with 34 workers (20.61%). Average job tenure was 3.5 years ± 1.2 years, with extremes of 1 year and 7 years. The occupational characteristics of the workers are presented in Table 2.
Table 2. Occupational characteristics of workers with low back pain.
|
Number |
Percentage |
Department |
|
|
Mining |
67 |
40.61 |
Plant |
58 |
35.15 |
Garage/Maintenance |
22 |
13.33 |
Safety |
7 |
4.24 |
Logistics |
5 |
3.03 |
Geology |
4 |
2.42 |
Occupational health and safety |
1 |
0.61 |
Human resources |
1 |
0.61 |
Workstations |
|
|
Welder |
10 |
6.06 |
Machine operator |
62 |
37.57 |
Electrician |
11 |
6.67 |
Maintainer |
3 |
1.82 |
Mechanic |
19 |
11.51 |
Metallurgist |
3 |
1.82 |
Factory operator |
34 |
20.61 |
Other professions |
23 |
13.94 |
Job seniority |
|
|
[1 - 3] years |
22 |
13.61 |
]3 - 5] years |
117 |
70.91 |
>5 years |
26 |
16.06 |
Total |
165 |
100
|
3.4. Clinical Signs
Clinically, isolated low-back pain was found in 136 workers (82.42%).
The Schöber index was abnormal in 111 low-back pain sufferers (67.27%). Mechanical pain was found in 113 workers with low back pain (76%), and radicular pain in 29 workers (17.58%). One hundred and eight workers (65.45%) had no known history of low-back pain prior to employment at the mine. The clinical characteristics of low-back pain are presented in Table 3.
Table 3. Clinical features of low back pain in workers.
Clinical features |
Number |
Percentage |
Complaints |
|
|
Isolated lumbago |
136 |
82.42 |
Lumbago + radiation to |
29 |
17.58 |
Type of pain |
|
|
Mechanical |
113 |
68.48 |
Inflammatory |
52 |
31.52 |
Pain intensity |
|
|
<4 |
42 |
25.46 |
4 - 5 |
17 |
10.3 |
6 - 7 |
103 |
62.42 |
≥8 |
3 |
1.82 |
History of low back pain |
|
|
Yes |
57 |
34.55 |
No |
108 |
65.45 |
IMC (kg/m2) |
|
|
<18.5 |
10 |
6.06 |
18.5 - 24.9 |
73 |
44.24 |
25 - 29.9 |
63 |
38.18 |
>30 |
19 |
11.52 |
Schöber index |
|
|
Normal |
54 |
32.73 |
Abnormal |
111 |
67.27 |
Doorbell sign |
|
|
Present |
20 |
12.12 |
Absent |
145 |
87.88 |
Lasègue sign |
|
|
Present |
55 |
33.33 |
Absent |
110 |
66.67 |
3.5. Triggering Factors
In our study population, a pain-triggering factor was present in 148 workers (89.7%). These were mainly whole-body vibration in 50 workers (30.30%), prolonged standing in 44 workers (26.67%) and manual handling in 34 workers (20.61%). Prolonged sitting was a trigger for low-back pain in 20 workers (12.12%). Figure 1 shows the distribution of workers suffering from chronic low-back pain, according to the triggering factors.
Figure 1. Distribution of workers suffering from chronic low back pain according to triggering factors.
3.6. Radiological Signs
A pathological image was found on standard radiography of the lumbar spine in 129 workers (78.18%), with a high proportion of cases of low back discarthrosis found in 61 workers (36.97%).
Table 4 shows the distribution of workers suffering from low-back pain according to radiological signs.
3.7. Socio-Professional Impact of Chronic Low Back Pain
Low back pain had an impact on walking perimeter in 54 workers (32.73%), on sleep quality in 60 workers (36.36%) and on sex life in 74 workers (44.85%). In addition, 57 workers (34.55%) reported restricted fitness for work due to low back pain, and 33 workers (20%) reported work stoppage due to the condition. Figure 2 shows the socio-professional impact of chronic low back pain among workers.
Table 4. Distribution of low back pain workers according to radiological signs.
Radiological sign |
Number |
Percentage |
Normal radiography |
36 |
21.82 |
Lumbar disc osteoarthritis |
61 |
36.97 |
Herniated disc |
4 |
2.42 |
Pinched disc |
52 |
31.51 |
Isthmic lysis |
6 |
3.64 |
Other |
6 |
3.64 |
Total |
165 |
100 |
Figure 2. Socio-professional impact of chronic low back pain in workers.
3.8. Factors Associated with Chronic Low Back Pain in Workers
3.8.1. Univariate Analysis
- Chronic lumbago and socio-demographic and occupational characteristics
In the univariate analysis, the socio-demographic and occupational data associated with chronic low back pain were gender (p = 0.004), level of education (p = 0.001), workstation (p = 0.001) and job seniority (p = 0.046). Table 5 presents the univariate analysis of the association between socio-demographic and occupational characteristics and the occurrence of chronic low-back pain in workers.
- Chronic lumbago and clinical signs
On univariate analysis, a significant association was found between low back pain and trigger factors (p = 0.000). On the other hand, no statistical association was found between the occurrence of low back pain and body mass index, or the workers’ history of low back pain.
Table 6 presents the univariate analysis of the association between clinical signs and the occurrence of chronic low-back pain in workers.
3.8.2. Multivariate Analysis
In the multivariate analysis, the factors independently associated with chronic low back pain were whole-body vibration (Fisher test = 12.7541; P = 0.000), male gender (Fisher test = 8.363; P = 0.004), and job seniority (Chi2 = 4.0234; p = 0.046).
The results of the multivariate analysis are presented in Table 7.
Table 5. Univariate analysis of the association between socio-demographic and occupational characteristics and the occurrence of chronic low back pain.
Socio-demographic and
professional characteristics |
Number |
Percentage |
P |
Age |
|
|
|
≤22 |
1 |
0.61 |
|
]22 - 32] |
47 |
28.48 |
|
]32 - 42] |
79 |
47.88 |
0.715 |
]42 - 52] |
34 |
20.61 |
|
]52 - 55] |
4 |
2.42 |
|
Gender |
|
|
|
Male |
156 |
94.55 |
0.004 |
Female |
9 |
5.45 |
|
Education level |
|
|
|
Primary |
30 |
18.18 |
|
Secondary |
45 |
27.27 |
|
Higher |
24 |
14.55 |
|
Out of school |
66 |
40 |
0.001 |
Marital status |
|
|
|
Married |
50 |
30.3 |
|
Single |
115 |
69.7 |
0.274 |
Workstation |
|
|
|
Welder |
34 |
20.60 |
|
Conductor |
62 |
37.57 |
0.001 |
Electrician |
11 |
6.66 |
|
Maintainer |
3 |
1.81 |
|
Mechanic |
19 |
11.51 |
|
Metallurgist |
3 |
1.81 |
|
Factory operator |
23 |
35.38 |
|
Other |
10 |
15.38 |
|
Length of service |
|
|
|
[1 - 3] years |
22 |
13.61 |
|
]3 - 5] years |
117 |
70.91 |
0.046 |
>5 years |
26 |
16.06 |
|
Table 6. Univariate analysis of the association between clinical signs and the occurrence of chronic low back pain.
Clinical data |
Number |
Percentage |
P |
IMC (kg/m2) |
|
|
|
<18.5 |
10 |
6.06 |
|
18.5 - 24.9 |
73 |
44.24 |
0.342 |
25 - 29.9 |
63 |
38.18 |
|
>30 |
19 |
11.5 |
|
History of low back pain |
|
|
|
Yes |
57 |
34.54 |
0.073 |
No |
108 |
65.45 |
|
Triggering factors |
|
|
|
Absent |
17 |
10.30 |
|
Prolonged sitting |
44 |
26.67 |
|
Prolonged standing |
20 |
12.12 |
|
Whole body vibration |
50 |
30.30 |
0.000 |
Handling |
34 |
20.61 |
|
Table 7. Multivariate analysis of factors associated with chronic low back pain.
Socio-professional characteristics |
Number |
Percentage |
Statistical tests |
P |
Triggering factors |
|
|
|
|
Absent |
17 |
10.30 |
|
|
Prolonged sitting position |
44 |
26.67 |
|
|
Prolonged standing position |
20 |
12.12 |
|
|
Whole body vibration |
50 |
30.30 |
12.7541 |
0.000 |
Handling |
34 |
20.61 |
|
|
Gender |
|
|
|
|
Male |
156 |
94.55 |
8.363 |
0.004 |
Female |
9 |
5.45 |
|
|
Length of service |
|
|
|
|
[1 - 3] years |
22 |
13.61 |
|
|
]3 - 5] years |
117 |
70.91 |
4.0234 |
0.046 |
>5 years |
26 |
16.06 |
|
|
4. Discussion
4.1. Limits of the Study
We carried out a cross-sectional descriptive and analytical study with retrospective collection, which did not allow us to follow the evolution of low back pain in workers; This does not make it possible to establish a clear causal link between low back pain and the various factors observed in the study. In addition, there could be an information bias due to the fact that not all of the mining company’s workers were included in the study. However, the results obtained represent a database that could prompt further studies with the aim of improving workers’ health in the country’s growing mining sector.
4.2. Prevalence of Chronic Low Back Pain
Out of a total of 880 workers participating in the study, 165 suffered from chronic common low-back pain, representing a prevalence of 18.75%. The average age of workers with low back pain was 37.21 ± 7.5 years. Males were most represented in the study, with 156 workers (94.55%). Sixty-six workers (40%) had no formal education. Machine operators were the most represented, with 62 workers (37.58%), followed by plant operators, with 34 workers (20.61%). Average job tenure was 3.5 years ± 1.2 years. Higher prevalences of chronic low-back pain were observed in several studies. In a study of musculoskeletal disorders in a port handling company in Cotonou, Mikponhoue et al. [5] noted a prevalence of chronic low back pain of 52.6%.
In France, in companies in the Pays de la Loire region, the prevalence of this pathology was high in both men and women, at 59% and 54% respectively [13]. Several other studies confirm the high prevalence of low-back pain in the workplace. Indeed, in 2021, this pathology was observed in 52% of building construction workers in Nepal [14]. In a hospital setting in Ouagadougou, its prevalence was 56.4% in the study by Ouedraogo et al. in 2010 [15]. The low prevalence of low back pain in our study could be explained on the one hand by the preventive actions carried out by the mining company’s occupational health staff, notably periodic medical check-ups of workers, staff awareness-raising on the prevention of musculoskeletal disorders in general and low back pain in particular, and monitoring of the working environment and conditions through workplace visits. On the other hand, this could be explained by the fact that our study only took into account cases of chronic low back pain, unlike other studies. Also, low back pain was reported in 17.58% of cases in our series. These results are comparable to those of Amon-Tanoh et al. [16], who reported 13.32% low back sciatic pain.
4.3. Factors Associated with Chronic Low Back Pain
In the univariate analysis, the factors associated with chronic low back pain were gender (p = 0.004), level of education (p = 0.001), workstation (p = 0.001) and length of service (p = 0.046). The presence of a precipitating factor such as whole-body vibration, prolonged standing or sitting and handling was strongly associated with low-back pain in workers (p = 0.000). On the other hand, no statistical association was found between the occurrence of chronic low-back pain and age, or marital status. Multivariate analysis revealed that the factors independently associated with this pathology among workers were whole-body vibration (Fisher test = 12.7541; P = 0.000), male sex (Fisher test = 8.363; P = 0.004) and job seniority (Chi2 = 4.0234; p = 0.046). In fact, workers subjected to vibrations were around 13 times more prone to low-back pain. Similarly, men were 8 times more prone to low back pain than women; job seniority of 4 to 5 years increased the risk of low back pain in mine workers by almost 4 times.
Several studies corroborate our findings. In their study of French companies, Fouquet et al. observed that men suffered more from low-back pain than women. [13] In Greece, Spyropoulos et al. also noted a statistically significant difference between the occurrence of low-back pain and gender among civil servants. [17] Job seniority has also been identified as a risk factor for low-back pain in workers, with a strong predisposition before 10 years’ experience. [7] At the start of their professional careers, lack of experience and the quest for promotion can lead young workers to over-invest in their workstations, putting them at greater risk of LBP than older workers. What’s more, given the extensive use of vibrating machinery on the mine site, a vibration prevention plan needs to be put in place at the mine, through the acquisition of quieter machines and regular equipment maintenance, in order to safeguard workers’ health.
Contrary to our results, age was a risk factor for low back pain among motorcycle cab drivers in Porto-Novo. [6] The same was true for overweight and awkward postures during work, notably bent-over posture, which was a risk factor for low back pain in their study. Although our study did not demonstrate an association between work postures and low back pain, in the literature, awkward postures are known to be a source of low back pain in the workplace and a factor in the transition to chronicity. The pauses observed in our workers’ work activity could partly explain our results. In their study of nursing staff in Senegal, Diatta et al. [11] noted that women were more prone to back pain than men. These same findings were made by Ouedraogo et al. [10] in Ouagadougou, in contrast to our data, where men were around 8 times more exposed than women. The low representation of women in our study could partly explain this state of affairs. What’s more, in mining, women are less likely than men to work in jobs requiring intense physical effort. Other authors have demonstrated a significant association between body mass index and the occurrence of low back pain in the workplace [10] [17]. Workers should be encouraged to engage in regular physical activity and control their diet to avoid becoming overweight.
5. Conclusion
The study carried out in a mine in Burkina Faso revealed a prevalence of chronic low-back pain of 18.75% among workers. Factors associated with the occurrence of this pathology were male gender, whole-body vibration and length of service. A multidisciplinary condition, low back pain should not be neglected, as it can have serious professional, social and economic consequences. Workers suffering from low-back pain were referred to a specialist for appropriate treatment. Preventing this pathology requires the implementation of an occupational risk prevention policy at mining sites, which takes into account the creation of occupational health services, the improvement of working conditions, the effectiveness of statutory medical check-ups and the participation of all workers in information, education and awareness-raising activities.