1. Introduction
Musculoskeletal disorders are widespread in the workplace, and preventing them has become a major public health issue given the very high number of people affected (1.71 billion in 2019 [
1]). These WMSDs are characterized by inflammatory and degenerative condition. These WMSDs are characterized by inflammation and degeneration of muscle, joint, and nerve tissues. They include all inflammatory syndromes (tendinitis, bursitis, etc.), tissue compression, particularly of the nerves (e.g., carpal tunnel syndrome), and all other regional pain syndromes (e.g., low back pain) that cannot be attributed to a known pathology [
2]. They are the origin of many work stoppages and induce very high direct and indirect costs.
The prevalence of WMSDs is very high among healthcare professionals [
3,
4]. Numerous studies have reported an overall prevalence of 83% among surgeons [
5,
6], 87% among dentists [
7,
8], 90% among midwives [
9,
10], 91% among physiotherapists [
11,
12], 91% among occupational therapists [
13], and 58% among osteopaths [
14]. A high prevalence of between 50% and 90% has also been widely demonstrated among nurses at the national [
15,
16], continental [
17,
18,
19], and worldwide [
20,
21,
22] levels. The authors highlighted that the most affected areas were the lower back, with a prevalence of nearly 60%, followed by the neck and shoulder, with a prevalence of 40–45%.
Many factors influence the overall WMSD prevalence and prevalence by body area. Some risk factors are related to professional practice and refer to issues such as awkward postures, handling heavy equipment or dependent patients, repeating numerous tasks throughout the day in static postures maintained for long periods of time, etc. [
23,
24]. These factors affect their quality of life at work and lead them to adapt their working environment, call for help to perform some care tasks, take more breaks, or reduce the use of specific care practices that aggravate their discomfort [
25,
26]. Other factors are related to the demographic characteristics of nurses. Studies have shown that age, gender, body mass index, marital status, level of education, and level of experience affect the prevalence of WMSDs among nurses [
27,
28]. Working conditions, including the number of hours worked per day and per week, heavy workload, and night shift frequency, also have an impact on the onset of WMSDs [
15,
29]. General working conditions also contribute to the development of WMSDs. They are related to the resources that each country allocates to the healthcare sector. With a larger share of Gross Domestic Product (GDP) invested, it is possible to improve these working conditions, in particular by providing hospital infrastructure, healthcare personnel, and ergonomic equipment, thereby reducing the risk of WMSDs. For example, Sun et al. [
20] have shown relationships between parameters related to a country’s development (i.e., financial resources) and the risk of WMSDs. The authors showed that the prevalence in eight body areas was higher in developing countries than in developed countries. With regard to staff, the nurse-to-bed ratio, i.e., the number of nurses administering care to patients, has also been considered at the local level, i.e., a department or institution [
30], or at the national level [
31] as a risk factor. Abedini et al. [
30] showed an effect of the nurse-to-bed ratio on WMSDs: a higher nurse-to-bed ratio reduces the WMSD prevalence. Finally, the degree of awareness is also a factor that could be involved in the prevention of WMSDs. The Human Development Index (HDI) is a macroscopic parameter at the country level that incorporates this aspect through an education index coupled with a life expectancy and national income index. It is therefore a complementary parameter to GDP and the nurse-to-bed ratio that could have an impact on the prevalence of WSMDs.
To our knowledge, few studies have conducted large-scale subgroup analyses, i.e., at the continental level or worldwide. The studies currently available mainly concern overall prevalence and prevalence by body area on a continent [
17,
19] or worldwide [
20,
22,
32,
33,
34]. Only recent studies have investigated the effect of some of these parameters on a large scale. Jacquier-Bret et al. [
22] assessed the effect of demographic parameters on the prevalence of WMSDs, while Sun et al. [
20] analyzed the effect of an economic parameter considering different countries in the world. Only one meta-analysis has tested the effect of experience on the prevalence of WMSDs among nurses in Asia [
19]. Analyses by continent have the advantage of highlighting specificities that cannot be seen worldwide and thus contribute to a better understanding of the appearance of WMSDs. These data provide evidence to support practice and improve the professional environment and quality of life at work for nurses through the implementation of appropriate policies, the development of new equipment, and more effective human resource management that incorporates planification and staff rotation cycles.
In this context, the aim of this study was to extend the analyses by continent, examining the effects of demographic, economic, and quality-of-life indicators on the prevalence of WMSDs among African nurses. Subgroup analyses will be conducted based on information on age, experience, body mass index, GDP, HDI, and the nurse-to-bed ratio. It has been hypothesized that a high GDP, HDI, and higher nurse-to-bed ratio leads to better working conditions and therefore a reduced prevalence of WMSDs.
4. Discussion
The objective of this literature review was to investigate the effect of demographic, economic, and quality of life indicators on the overall and body area prevalence of WMSDs among African nurses. Six parameters were used to conduct subgroup analyses from data collected in 18 cross-sectional studies involving 4266 nurses. Three anthropometric parameters (age, years of experience, and BMI), two economic parameters (GDP and nurse-to-bed ratio), and one quality of life parameter (HDI) were considered.
4.1. WSMD Prevalence Among African Nurses
The included studies had an overall prevalence ranging from 61.0% to 97.8%, excluding the two studies with the lowest prevalence, i.e., 38.0% [
28] and 48.1% [
59]. This range corresponds to that presented in the scoping review by KgaKge et al. [
18], who reported values between 57.1% and 95.7%. The prevalence pooled by the meta-analysis was 77.7%. It is equivalent to that reported by Sun et al. (77.2% [
20]) on worldwide scale and between the values found by Ellapen et al. (71.85% [
21]) and Saberipour et al. (84.2% [
16]). However, the prevalence in Africa appears to be lower than that observed in Asia (84.3% [
19]) and Europe (87.8% [
17]). As regards body areas, the most affected area was the lower back, with a prevalence of 61.2%, which was twice as high as in other areas. This result is consistent with the findings of numerous studies in the literature conducted in many countries among nurses. The neck and upper back are also significantly affected, with one in three nurses reporting the presence of WMSDs. These results can be explained by information related to risk factors reported in cross-sectional studies. Nurses repeat many care tasks in awkward positions involving bending and twisting, which are widely considered to be factors that contribute to the onset of WMSDs [
25,
26]. For the upper limbs, the shoulder was the most affected area (36.1%), well ahead of the wrist (26.3%) and elbow (13.8%). Occupational demands are therefore concentrated on the shoulder area, particularly when carrying heavy materials/equipment and during lifting or transferring patients [
62,
63]. Finally, for the lower limbs, the knee and ankle also had values of around 35%, indicating a significant prevalence of WMSDs. These high rates can be explained either by maintaining static postures, mainly standing, for long periods of time [
64], or by numerous movements during a 12 h shift [
65].
These results show that nurses are healthcare professionals who are highly exposed to WMSDs due to their extensive daily tasks. Numerous adjustments are often necessary to enable them to continue their work [
25] while considering physical, psychological, and environmental constraints [
66]. It is therefore important to continue development and research in order to propose technical, organizational, and educational solutions aimed at maintaining a satisfying quality of life at work.
4.2. Effect of Demographic Parameters on WSMD Prevalence
Based on the 18 studies included and a sample of 4266 nurses, three parameters were used to conduct the subgroup meta-analyses: age, years of experience, and BMI. We observed a decrease in prevalence with age, mainly for overall prevalence and for the upper body. However, the lower back did not appear to be affected by age and showed a high prevalence (>65%). This result contrasts with the results presented in previous studies. Heiden et al. [
67] found an increase in the prevalence of WMSDs with age for the neck, shoulder, lower back, and overall in India, based on a study of 273 nurses. In a meta-analysis conducted in China (23 studies and 21,042 nurses), Wang et al. [
15] found an age effect with a significant odds ratio of 1.69 (95% CI: 1.16–2.45) for nurses over 35 years of age. In contrast, Mahajan et al. [
62] found no age effect on prevalence between nurses under 30 and over 40 in a sample of 190 nurses. Under these conditions, it is difficult to draw conclusions about the effect of age on the prevalence of WMSDs. However, considering age in combination with other parameters related to the country or continent could be relevant for future work.
In our study, an effect of experience was observed on overall prevalence. This result was also observed in the study by Wang et al. [
15] on a sample of 21,042 nurses in China. The authors found an odds ratio of 3.30 (95% CI: 1.84–5.92). Analysis by body area showed that the increase in prevalence with experience was mainly concentrated in the lower limbs. Thus, the accumulation of years of nursing practice in Africa would have a greater impact on the hip, knee, and ankle, particularly due to prolonged maintenance of static postures, mainly standing [
64], or significant travel of around 10 km during a shift, as reported in the literature [
65]. These strain factors have an even greater impact when BMI is high, as shown by the increase in the prevalence of WMSDs in the knee and ankle among overweight nurses (
Table 7).
However, in order to further investigate these observations, it would be useful to have a precise breakdown of the time spent performing each task during a shift [
68]. By combining this information with the risk factors associated with the appearance of WMSDs, it would then be possible to attribute specific prevalence to clearly identified activities.
4.3. Effect of Economic Parameters on WSMD Prevalence
A subgroup analysis was performed to assess the effect of the nurse-to-bed ratio on the prevalence of WMSDs over 12 months, both overall and for the nine body areas. The analysis showed that five of the nine body areas had a decrease in the prevalence with an increase in the nurse-to-bed ratio. This result is consistent with the literature, which reports that an increase in this ratio reduces stress and workload, as there are more nurses for a given number of beds [
30,
69]. However, this result could be tempered, as other authors have observed significant emigration of nurses in African countries [
70]. This is resulting in a shortage of personnel on the African continent. Available data for 10,000 inhabitants shows that for most countries, the average number of nurses is well below the world threshold of 37.7. In our study, only South Africa and Libya had a higher value (63.9 and 63.8, respectively) [
44]. In addition, the number of beds is very low and well below the world average of 3.3 per 1000 inhabitants [
71]. Countries such as Ethiopia, Nigeria, and Uganda have fewer than 1 bed per 1000 inhabitants. This lack of healthcare facilities results in an artificial increase in the nurse-to-bed ratio, which minimizes the relevance of this indicator in analyses for this continent.
The second subgroup analysis was conducted based on the GDP of each country included in the analysis. This macroscopic parameter represents a country’s capacity to produce wealth. The results showed an increase in WMSDs with GDP for hip and knee. For other body areas, no direct link between GDP and prevalence was found, which does not validate the hypothesis that a higher level of wealth would offer better working conditions and therefore a lower risk of WMSDs. A country’s wealth does not necessarily mean a lower risk of WMSD. This could be explained by the fact that GDP is only linked to nurses through the percentage of GDP redistributed to healthcare. Thus, the way in which wealth is redistributed is not necessarily consistent across all countries for a given GDP. For example, Nigeria (GDP of
$158 billion) and Kenya (
$131 billion) have public health expenditures of 0.9% and 3.5%, respectively. Similarly, public health expenditure was twice as high (4% vs. 1.8%) in Tunisia (GDP of
$56 billion) and Uganda (GDP of
$64 billion) for a similar GDP [
72]. Furthermore, the small number of studies and the specificity of healthcare facilities may influence the link that could exist between GDP and the risk of WMSDs. Indeed, GDP is reported for a country, while the prevalence of WMSDs measured is often linked to a facility, whose financial, technical, and structural resources do not necessarily reflect the wealth of the country. Therefore, the link between resources and prevalence needs to be investigated in greater depth. One approach could be to link the degree of development of a facility (human, structural, and financial resources, number of beds, etc.) with the associated WMSD risk level.
4.4. Effect of Quality of Life on WSMD Prevalence
The analysis was conducted based on the HDI of different countries. This composite index represents the human development rate of a country in the world based on life expectancy, access to education, and standard of living [
73]. The results showed an increase in prevalence for seven body areas when the HDI was high (no effect was observed for the elbow and hip). Because the HDI takes life expectancy into account, a country with a high HDI has a population that lives longer and therefore works longer. Several studies have reported an effect of age on the prevalence of WMSDs: older people had a higher prevalence of WMSDs [
15,
67]. This relationship may therefore explain the increase in prevalence observed with the HDI between countries in Africa. In addition, the HDI incorporates access to education and therefore to knowledge. It is widely recognized that knowledge of workplace ergonomics among nurses is an important factor in minimizing loss of time and workforce, early disability, and early fatigue [
74], and therefore ultimately preventing the onset of WMSDs. Several authors have highlighted different levels of ergonomic knowledge among nurses in relation to the occurrence of WMSDs. Zakeriyan et al. showed that nurses’ knowledge of ergonomics was at an intermediate level and that there was a significant relationship between this knowledge and WMSDs: the more nurses knew about ergonomic principles at work, the less they suffered from WMSDs [
75]. Mohammad et al. found that nurses had a low level of knowledge of ergonomic principles in the workplace, poor workplace ergonomics, and a high prevalence of WMSDs [
76]. Finally, Juibari et al. found that nurses in Golestan had a high level of knowledge, but that there was no significant relationship between these two variables [
77]. The ergonomic knowledge level among nurses therefore varies greatly and does not always have a direct impact on the occurrence of WMSDs. In the context of our study, African countries with a high HDI have not necessarily acquired the knowledge necessary for the prevention of WMSDs, or else its application in working conditions is not possible or optimal due to a restrictive environment or an expanded workplace. This could therefore explain the higher prevalence observed in the results, despite a high HDI. It therefore appears necessary to maintain and strengthen ergonomic–educational policies for nurses in Africa in order to improve their occupational health and reduce the risk of WMSDs.
Despite high HDI scores in some countries, there has been a strong tendency among African nurses to want to leave their jobs [
78] or to want to work in better conditions, i.e., in other countries. Currently, several countries have difficulties to adequately compensate nurses (salaries, pensions, or other benefits) due to a lack of resources [
79] or other economic reasons, such as inflation in Nigeria, for example [
80]. This situation prevents them from meeting their basic needs and working comfortably. As a result, African nurses are migrating to destinations offering better social benefits [
81].
4.5. Solutions to Prevent and Reduce WMSDs
This review has highlighted that the occurrence of WMSDs is multifactorial and widespread in Africa. It is therefore important to continue developing and implementing ergonomic programs and organizational work strategies to reduce their impact. Interventions aimed at reducing WMSDs proposed in the literature fall into five categories: (a) individual, (b) task- and equipment-specific, (c) work organization and task design, (d) work environment, and (e) multifactorial [
82]. Individual actions focus on behavior and health preservation at work. Awkward postures and repetitive tasks are two major factors in the appearance of WMSDs [
83,
84] and must be limited. Physical activity should be encouraged because of its positive effect on WMSDs [
85,
86] and to prevent new episodes of pain [
87]. Programs aimed at improving nurses’ knowledge of ergonomic principles, familiarizing them with appropriate working methods, and using therapeutic equipment should be promoted, as they play an important role in reducing WMSDs among nurses [
75]. The ergonomics of equipment and knowledge of how to use it must also be considered. Targeted interventions on issues such as manual and mechanical handling of patients or moving and transporting heavy equipment are all factors that contribute to significantly reducing injuries related to musculoskeletal disorders [
88,
89]. Finally, workplace environment interventions are another important factor in the prevention of WMSDs. Organizing and limiting shifts [
90] and reducing stress by reducing the time pressure associated with a heavy workload [
91] (e.g., by reducing the number of patients per shift or adjusting staffing levels, i.e., the nurse-to-bed ratio) are recommendations that should be considered. Finally, the category of multifactorial interventions includes a combination of different types of interventions [
92].
4.6. Limitations
Some limitations can be addressed. The first concerns the nurse-to-bed ratio. On the one hand, it is difficult to obtain reliable data and, on the other hand, it relates to the entire country. However, the analyses presented in the various cross-sectional studies were often conducted in a single institution. It would be much more relevant to have this parameter available for each institution, which would more realistically reflect the conditions in which nurses work. Such an approach could lead to more accurate results for WMSD prevalence.
The second concerns the high degree of heterogeneity observed in the results despite the subgroup analyses. From a methodological viewpoint, the different questionnaires used and the subjective nature of the responses are a significant source of variability. In addition, sample size and working conditions (department, specialty, etc.) are parameters that can influence the measurement of prevalence. More in-depth subgroup analyses considering several criteria could refine the results presented.
A third limitation concerns the number of studies included in the subgroup analyses. With regard to overall prevalence and prevalence by body area, all of the studies included provide exhaustive data. However, demographic, socioeconomic, and psychological data for the sample are not always detailed, which limits the subgroup analyses.
The last one relates to the methodological criteria for selecting and including studies in the meta-analysis. Restricting the research to original peer-reviewed studies written exclusively in English may have led to the omission of some studies that could have been relevant in assessing the prevalence of WMSDs among nurses in Africa.
5. Conclusions
WMSDs are common among African nurses, particularly in the lower back, neck, shoulders, knees, and ankles. Demographic, economic, and quality-of-life indicators have an impact on the prevalence of WMSDs. The nurse-to-bed ratio should be viewed with caution, as it may be skewed in Africa. Few countries (Libya and South Africa) have sufficient nursing staff, and all have far fewer beds than the world average, which artificially increases the value of this ratio. In addition, a country with a high HDI may have poor working conditions, leading to an increase in WMSDs. Future work could examine the effect of the nurse-to-bed ratio by considering the resources of a facility and conducting more in-depth analyses by subgroup, particularly by specialty. The ongoing development of ergonomic programs and organizational work strategies remains a major challenge for improving the well-being and safety at work of African nurses.