Although the prevalence of WMSDs and their related management have been extensively investigated, yet important gaps in surveillance systems remain, and a significant proportion of the global working population continues to live and work with these disabling conditions. In the present study, we have focused on a representative sample of the Italian working population, assessing their exposure perception to the biomechanical/ergonomic and VDU risks and the actual health surveillance programs for these two risks proving strong association with WMSDs.
The assessed prevalence of low Back pain, Shoulders, neck and/or upper limbs pain and Lower limb pains assessed in this study are in line with the literature. Indeed, WMSDs are the second most common cause of disability worldwide measured by YLDs, with low back pain ranking as the most frequent condition [21].
Some sociodemographic variables (age, sex, educational level and BMI) seem to be closely associated with the presence of WMSDs confirming available evidence. The WMSD prevalence increases with age and reach its maximum in the range between 55 and 64 years being consistent with data by the EU- OSHA. Indeed, in this age range the number of self-reported symptoms is 1.7 times higher than the range of 25–34 [8]. The recorded evidence of increasing WMSDs with advanced age may be related to the fact that older workers are becoming more prevalent in the work force due to improvement in health, increased life expectancy and a higher rate of employment in companies [22]. Women reporting WMSDs more frequently than men also agrees with evidence observed in other previous studies [23]. Indeed, women who do the same job tasks as men often face a higher risk of WMSDs that may be due to both biological divergences as well as differences in social roles, activities and behaviors [23]. Moreover, they have a moderately increased risk of chronicity compared to men [24]. Education is likely a protective factor for WMSDs that may be due to the association between higher level of education and working position and therefore a decreased risk for these disorders. Farioli et al. showed that the prevalence of back and upper limb pain increased with age and was higher among women and workers with lower educational level in a population of 43,816 subjects from 34 European countries [25]. Regarding BMI, it is widely acknowledged that obese or overweight workers have a greater risk of developing WMSDs, as they are more susceptible to risks from vibrations, repetitive movements and manual handling of loads [26]. Obese workers are twice as likely as normal weight workers to develop upper limb tendinopathies and four times as likely to develop carpal tunnel syndrome. In accordance to our data, BMI was also associated with musculoskeletal symptoms of the lower extremity [27]. Furthermore, obesity markedly increases the risk of disability retirement due to WMSDs [28].
The strong association between work in the commerce sector and leg pain could possibly be linked to the long time work standing in this sector (shop assistants, waiters). The prolonged standing work posture has a strong association with pain in feet and legs, with the onset of varicose veins, and chronic venous insufficiency [29].
Among the others, most interesting findings emerged by our study are those related to the risk perception compared to risk detection linked to MSDs. Such findings showed that workers perceiving exposure to biomechanical/ergonomic and VDU risks, but not included in a health surveillance program for these occupational risk factors (Risk Perceived/No Risk Detected), had significantly higher odds of reporting MSDs, similarly to those perceiving exposure and included in a health surveillance program (Risk Perceived/ Risk Detected). These results were unexpected and would suggest a rather high risk profile (referring to biomechanical/ergonomic and/or VDU risks) for these subjects, at least similar to that of workers undergoing health surveillance medical examinations. However, it is important to underline that the items of questionnaire measuring the occurrence of WMSDs did not provide for the detection of a time frame and consequently it should be considered that workers not included in a health surveillance program may have had WMSDs for only a short period of time, whereas workers included in the program possibly had chronic complaints. Therefore, this result should be considered with caution and further investigated in future using appropriately designed and targeted studies. Nevertheless, it is still possible to hypothesize that the OSH management system may not have been able to intercept them, thus highlighting some potential critical issues in the evaluation and management process of these specific occupational risk factors. There are several possible reasons that can explain this finding and probably each of them contributes partially, but synergistically, in determining the evidence here reported. Obviously, considering the cross-sectional design of our study, we are not able to determine or identify causal correlations between the results obtained and any underlying determinants but, on the basis of the observed associations, we can still try to put forward plausible hypotheses. First of all, it should be considered that the available evaluation tools and strategies applied for biomechanical/ergonomic risk assessment and management are based on observational methods that require specific competencies and adequate training in order to be selected and used properly. For example in this regard, among the numerous tools available, there is no single one that is suitable for all purposes and consequently the choice of the most appropriate method may be quite challenging [14]. Moreover, the final users (i.e. occupational physicians or OSH technicians) of these evaluation instruments could have a limited knowledge since the operating indications are often provided in unfamiliar language or the methods have been developed for a specific work sector and their translation into a different professional context is complex and not always reliable [14]. Therefore, an initial possible explanation of this result could lie in a potential incorrect application or inadequate biomechanical/ergonomic risk assessment by the OSH management system.
Moreover, it is important to keep in mind that WMSDs are associated with numerous and different risk factors, some of which are socio-demographic (e.g. age, sex, BMI, leisure physical activity) but others are closely related to the working activities carried out [30]. In fact, it is no coincidence that MSDs prevalence is significantly higher in workers compared to general population since several workplace hazard exposures such as manual handling of heavy loads, awkward postures, hand-arm and whole body mechanical vibrations, repetitive movements may play an important role in their onset [31, 32]. Most importantly, in many industrial sectors the damaging action of these occupational risk factors occurs at the same time on the same target organ as the working activities involve a simultaneous exposure of the worker. Therefore, the case could arise in which the single assessment of each of the aforementioned risk factors highlights a controlled risk condition with exposure levels that are below the values that require the application of secondary prevention measures such as the health surveillance. Consequently, these workers are probably not subjected to health surveillance medical examinations (as the risk assessment and management system would not provide for its activation) but, in the long run, chronic and simultaneous exposure to multiple and synergic occupational risk factors might determine the occurrence of WMSDs. These complex situations involving multiple exposures to risk factors with potential synergistic action should be carefully evaluated by the OSH management system also in consideration of the results observed in our study.
Indeed, regarding the biomechanical/ergonomic risk, workers who perceive the risk but are not included in a health surveillance program for such risk (Risk Perceived and No Risk Detected) are mainly employed in transportation, warehousing/information and communication that are particular working activities often characterized by the simultaneous exposure to awkward postures, mechanical vibration, manual handling of heavy loads and repetitive movements. Furthermore, they are mainly in the age range of 19–24 years and this may be due to the precarious employment conditions, such as short-term contracts or low-wage work, which are more common among younger workers in Europe [15] and seem to be related to lower standards of OSH protection [16]. In this regard, it should be considered that younger workers have less access and a lower awareness of OHS issues compared with older workers, therefore, constituting an important challenge for OSH systems [4].
With regard to VDU risk, these workers (Risk Perceived/No Risk Detected) are in the age range of 45–54 years and they are mainly involved in the professional, financial and business services. Concerning the higher OR of workers who, although not included in the health surveillance system for exposure to VDU risk factor, perceived this exposure as high, it is noteworthy that according to regulatory framework currently in force in Italy VDU worker spend at least 20 h of their weekly working time using a VDU unit. Usually, the assessment of this working time is carried out by means of validate questionnaire and/or checklists [13]. However, even if a subject is not classified as a VDU worker it could happen that its actual exposure time to the VDU unit is significantly higher (often >20 h). Furthermore, also in this case, this type of work involves exposure to additional risk factors (i.e. awkward postures and repetitive movements of the upper limbs) closely related to WMSDs. This hypothesis would be further corroborated by the observed positive and statistically significant association between Lower limb pain and working hours. Moreover, it is possible to speculate that, if these subjects are not actually classified as VDU workers, then also the attention paid to them by the OSH management system, both in terms of prevention and protection measures and training and information programs, can be significantly lower than their VDU colleagues.
WMSDs often pose also major threats to mental health and can be associated with increased risk of developing other chronic health conditions [33]. Data from our study also support the correlation between psychosocial factors and MSDs, already highlighted in other studies. Indeed, Sobeih et al. [34] conducted a systematic review examining the link between psychosocial factors and the presence of WMSDs among construction workers. All studies reported a correlation between WMSDs and at least one psychosocial factor, the most frequent being work-related stress, poor professional satisfaction, low control over work and pressing demands in terms of work performance. Leka et al. [35] identified 16 studies describing the existence of a link between psychosocial factors (including stress, long working hours, no control over their work, lack of social support) and onset of WMSDs including injury from biomechanical overload (muscle injury due to frequent use of the same muscles) and pain in the upper limbs, neck and back. A correlation between WMSDs and anxiety and depression was observed by Magnavita et al. [36] on caregiving workers. The authors showed, that Back pain was associated with workload, depression, age and anxiety; cervical pain was associated with psychosocial factors of stress, female sex and anxiety.
Moreover, in the present study, training in health and safety was found to be a protective factor for Back pain and Upper limb pain confirming the crucial role of education and training. However, it is currently agreed that training alone is not enough, prevention plans need an overall strategy, that must take into account all the aspects that influence the biomechanical risk: organizational (quantity of operators; definition of procedures; working times; working relationships), technical-structural (availability and quality of tools/aids; typology and organization of work spaces) and cultural (adequate training and knowledge of handling procedures and techniques). Over time, only global strategic interventions have proven to be able to adequately manage the risk for operators, reducing disease, absences and reflected costs. Other partial interventions, such as the training of healthcare operators have shown enormous limits of effectiveness, making the relative economic investments fruitless [37].
All in all, the main strength of this study is that this allows a comparison among workers’perceptions of exposure to some occupational risks, their actual involvement in health surveillance program, and the emergence of MSDs. Few previous studies focused on the effectiveness of OSH management system in detecting risks associated to MSDs. Thank to our results we offered thus insights and reflections on tools and methods used for the evaluation to contribute in improving the OSH risk management in organizations.
Some limitations of this study must be addressed too with a view to future improvements. First, the cross-sectional design allows us to describe associations but not drawing causal inferences about the effects of the different variables on MSDs. Nevertheless, data collected are part of a national survey (INSuLa) and are based on a large representative sample, that represents a strength of this study since allows to obtain valid results, which adequately reflect population distribution. Moreover, this survey is now becoming a monitoring system to follow changes over time. A new wave was already conducted in 2019 on further 8000 workers and preliminary data will be presented in 2020. As second limitation is related to the self-reporting of measures. Particularly, data on MSDs are self-report and refers to the last 12 months, thus might tend to have a recall biased, namely error that can occur when participants do not remember their experiences accurately or omit detail. Combining self-report data with other information by using a multi-method assessment provides more likely accurate data on the outcome. Thus, ongoing studies are focussing on collecting self report data and integrate such information with medical examination outcomes or diagnosed information.