Homogeneity Criteria in Occupational Medicine: A Focus on Women’s Health in Musculoskeletal Disorders

Abstract

Musculoskeletal disorders (MSDs) are a major occupational health concern, especially for women in physically demanding jobs. Despite efforts to standardize risk assessment in occupational medicine, the lack of homogeneous criteria limits the comparability and applicability of the findings, particularly concerning gender-specific risks. A systematic review was conducted across PubMed, Scopus, and Web of Science, following PRISMA guidelines. The review included primary studies in English or Italian that applied standardized criteria to assess MSDs among working women. The search strategy was built using the PICO framework, focusing on uniform assessment methods for MSDs in occupational contexts. Out of 416 initially retrieved records, 5 studies met the inclusion criteria. These studies, conducted in North America, Europe, and Asia, applied diverse yet standardized tools such as the ISO 2631, INRS/Saltsa guidelines, ergonomic assessments, and functional capacity evaluations. Female representation ranged from 12% to over 80%, highlighting the underrepresentation of women in some studies. All studies incorporated criteria to ensure population or exposure homogeneity. Although standardized methods are increasingly being used in MSD research, only a few studies integrate a gender-sensitive approach. This review underscores the need for personalized occupational health models that consider sex and gender differences, promoting equitable and effective fit-to-work assessments.

1. Introduction

Musculoskeletal disorders (MSDs) among workers represent one of the leading causes of disability and the most common health issue faced by women and men of working age in their daily lives [1]. The implications extend beyond the temporary incapacity to fully perform one’s job; it is also necessary to consider the direct economic loss, namely, the expenses that individuals incur to address their health problems, as well as the indirect costs borne by the workplace or, more broadly, society due to the reduced productivity of the affected workforce [1]. Since the 1990s, MSDs have become not only a challenging issue for ergonomists worldwide [2] but have also become a national prevention priority in some countries [3].

Several studies have reported that gender differences in the prevalence of work-related musculoskeletal disorders (MSDs) may stem from varying levels of occupational exposure between men and women [4,5]. While MSDs affect workers across all sectors, women face additional risk factors, including the use of tools and equipment that have not been designed with female physiology in mind [6]. Traditionally, across the globe, work tools, equipment, and personal protective devices (PPE) have been designed and tested for the male body. As a result, women may struggle with improper fit, which can hinder usability and contribute to discomfort during use. Poorly fitting equipment can lead to awkward postures and ergonomic strain, ultimately increasing the risk of MSDs—especially in women [7,8].

Among female workers, those employed in office-based roles and working with video display terminals (VDTs) are particularly vulnerable. In fact, multiple studies have identified a higher risk of MSDs in female office workers (OR 3.6; 95% CI: 1–12) [9,10]. For instance, the Italian study by Santoro et al. [11] found that, among women working remotely without ergonomically adequate home office setups, the most frequently reported symptoms were neck/shoulder pain, back or lower limb pain, and arm pain. Despite experiencing these symptoms, only 15.4% of those with neck/shoulder pain, 16.5% with back/lower limb pain, and 20.0% with arm pain reported taking posture-related or visual breaks from their workstation or screen.

In 2009, Lapointe et al. also found that, while male VDT workers predominantly reported lower back pain associated with posture-related occupational risk factors, women more frequently experienced symptoms in the shoulders, neck, lower back, and upper limbs [12]. According to Sorrentino et al., women are also more likely to be affected by both musculoskeletal and psychological issues due to occupational segregation and their higher share of domestic responsibilities [13]. These challenges are particularly common in professions that require intense physical and emotional engagement, such as healthcare. Female nurses, for example, are among the occupational groups most at risk of both physical strain and psychological conditions such as depression and burnout [14].

Through systematic reviews, such as this one, awareness can be raised about these increasingly prevalent issues in occupational health, particularly regarding gender disparities.

To date, numerous attempts have been made to analyze and evaluate the reliability of observational ergonomic assessment scales for workplaces [15,16], as well as various preventive and corrective measures aimed at avoiding MSDs [17,18,19,20]. In this regard, it is essential to consider gender differences from an anatomical and physiological standpoint, particularly concerning muscle compliance and structural resistance to physical effort.

In this context, some authors have sought to develop a gender-specific Job Exposure Matrix (JEM) to study its predictive validity for musculoskeletal pain [21]. However, more generally, the assessment of musculoskeletal disorders in occupational medicine has become highly heterogeneous, lacking uniform and consistent analytical criteria due to the presence of numerous classifications used at national or, at best, supranational levels. Although the National Institute for Occupational Safety and Health (NIOSH) established a dedicated health program for musculoskeletal disorders [22], to date and to our knowledge, there are no studies in occupational medicine that have uniformly analyzed musculoskeletal disorders among working women. The aim of our study was to conduct a systematic review of the literature that defined criteria for uniformity in fit-to-work assessments in occupational medicine, related to exposure to musculoskeletal risks in the workplace, considering workers’ characteristics such as anthropometric measurements, age, and gender, both female and male.

2. Results

The initial search across PubMed, Scopus, and ISI Web of Knowledge yielded 416 potentially relevant studies. After the removal of 135 duplicates, three researchers independently screened the remaining records. Any disagreements regarding the inclusion or exclusion of studies were resolved through internal discussion. Following the exclusion of 251 studies based on abstract screening, the full texts of 30 articles were assessed for eligibility. Of these, 25 were excluded after full-text review, following the same inclusion criteria stated above. Ultimately, five studies met the inclusion criteria and were incorporated into the systematic review. Figure 1 shows the complete article selection process.

The five studies included in the review were conducted across different geographical regions: two in North America (the United States and Canada, 40%), two in Europe (France and the Netherlands, 40%), and one in Asia (Iran, 20%). This geographical distribution reflects the global relevance and multidisciplinary research interest in the topic.

The sample sizes varied considerably, ranging from 19 to 2685 participants. The mean age of participants was reported in three studies and ranged from 39.5 to 48 years. The proportion of female participants varied between studies, with values ranging from 12% to 61%.

In terms of occupational classification, three studies focused on blue-collar workers (including hospital workers, agricultural machinery operators, and weavers), while two involved mixed blue- and white-collar populations from various sectors (e.g., industrial workers, farmers, technicians, and professionals).

All five studies investigated musculoskeletal disorders (MSDs), with most reporting multiregional disorders (including the neck, back, upper, and lower limbs). Two studies focused specifically on upper limb disorders, such as rotator cuff syndrome, epicondylitis, carpal tunnel syndrome, and tendinitis.

Importantly, all studies applied homogeneity criteria for population or exposure characteristics. These included standardized tools and methods such as ISO 2631 [23] standards for vibration exposure, structured ergonomic analyses, European consensus documents (INRS/Saltsa), functional capacity evaluations (EK FCE) [24], and detailed postural and task-based classifications.

These findings suggest that, despite geographical and occupational differences, there is a consistent effort across studies to apply standardized methodologies to assess and interpret musculoskeletal risk factors and outcomes.

Table 1. Summary of the main characteristics of the studies included in the systematic review, including country, sample size, gender distribution, occupational category, type of musculoskeletal disorders (MSDs), and applied homogeneity criteria.

Author (Year)	Country	Sample Size (n.)	Mean Age (±SD)	% Female	Occupational Category (e.g., White-Collar, Blue-Collar, Mixed)	Type of MSD	Homogeneity Criteria Applied (Y/N)	Homogeneity Criteria Details
Mayton A.G. et al. (2008) [25]	USA	50	48 y	12%	Blue-collar (heavy machinery agricultural operators)	Multiregional disorders	yes	Exposure to whole-body vibrations (WBV) according to ISO 2631 standards
Choobineh et al. (2007) [26]	Iran	1439	N.D.	80%	Blue-collar (weavers)	Multiregional disorders: neck, shoulders, back, hands/wrists, knees, etc.	yes	Standardized ergonomic analysis
Roquelaure Y. et al. (2006) [27]	France	2685	39.5 y	41.7%	Mixed: farmers, craftsmen, managers and professionals, technicians, employees, skilled and unskilled workers	Upper limb disorders: rotator cuff syndrome, lateral epicondylitis, ulnar cubital syndrome, carpal tunnel syndrome, wrist tendinitis, and De Quervain’s disease	yes	European consensus criteria document (INRS/Saltsa)
Messing K. (2017) [28]	Canada	19	N.D.	>60%	Blue-collar (hospital workers, HCAs)	MSDs related to the spine, shoulders, and back	yes	Classification into ‘light work’ and ‘heavy work’; postural analysis; direct observation; body map pain questionnaires
Wind H. et al. (2009) [29]	The Netherlands	54	46 y	61%	Mixed	Multiregional disorders	yes	EK FCE (Evaluation of Functional Capacity)

shows the main characteristics of the studies included in the systematic review.

2.1. Qualitative Analysis of the Included Studies

A qualitative synthesis was conducted to complement the quantitative overview of the included studies. The aim was to highlight, for each study, the specific research focus, methodological strengths, weaknesses, and overall quality as assessed through the Newcastle–Ottawa Scale (NOS) [30]. To further ensure methodological transparency, the risk of bias assessment was conducted using the Newcastle–Ottawa Scale (NOS), independently by three reviewers. Each study was evaluated across the three NOS domains (selection, comparability, and outcome), and discrepancies in scoring were resolved by discussion until full consensus was reached. Based on the total NOS score, the risk of bias was categorized as low (7–9 points), moderate (5–6 points), or high (≤4 points). This classification was used to qualitatively support the synthesis of evidence presented in the Results section.

2.1.1. Mayton A.G. et al. (2008) [25]: NOS Score: 7/9 (High Quality)

This study investigated the relationship between whole-body vibration exposure and musculoskeletal symptoms among heavy machinery agricultural operators. The application of ISO 2631 standards [23] for vibration exposure represented a methodological strength, ensuring comparability across studies. The mean age (48 years) reflected a mature working population, useful for understanding MSDs in middle age. However, the small sample size (n = 50) and low representation of women (12%) limited the generalizability and prevented gender-specific analyses. Despite these limitations, the study’s structured exposure assessment supports its overall methodological validity.

2.1.2. Choobineh et al. (2007) [26]: NOS Score: 8/9 (High Quality)

Conducted in Iran, this large-scale study examined musculoskeletal disorders among female weavers using standardized ergonomic assessments. The very high female participation (80%) and large sample (n = 1439) enhanced the representativeness and statistical power. The main limitations were the lack of a reported mean age and the reliance on self-reported data, potentially introducing recall bias. Nevertheless, the comprehensive ergonomic analysis and consistent methodology led to a high NOS rating, confirming the study’s robustness and reliability.

2.1.3. Roquelaure Y. et al. (2006) [27]: NOS Score: 7/9 (High Quality)

This French multicenter study explored upper limb MSDs across multiple occupational categories using the INRS/Saltsa European consensus criteria. Its strengths included the large sample size (n = 2685), detailed case definitions for upper limb disorders, and standardized diagnostic criteria. However, the cross-sectional design limited causal inference, and the absence of stratified analyses by gender reduced the interpretability. The study was nevertheless rated as methodologically strong due to rigorous data collection and validated assessment tools.

2.1.4. Messing K. (2017) [28]: NOS Score: 6/9 (Moderate Quality)

This qualitative study critically analyzed how ergonomic standards and biological assumptions can disadvantage women, particularly hospital care assistants. Strengths included its gender-sensitive perspective, mixed methods approach (direct observation, postural analysis, and body mapping), and focus on real work environments. The small sample size (n = 19) limited the external validity, but the depth of analysis offered unique insight into gendered occupational risks. Its moderate NOS score reflects solid methodological integrity within a qualitative research framework.

2.1.5. Wind H. et al. (2009) [29]: NOS Score: 7/9 (High Quality)

This Dutch study assessed how Functional Capacity Evaluation (EK FCE) data influence physicians’ judgment of work ability in disability claims. The use of an objective standardized tool represented a key methodological strength. The balanced gender composition (61% women) and clear link between measured capacity and clinical decision making increased its practical value. The relatively small sample size (n = 54) slightly limited the statistical strength but not the internal validity. The high NOS score supports its reliability and methodological soundness.

Overall, the NOS scores ranged from 6 to 8, indicating generally good methodological quality across the included studies. These findings support the validity of the results discussed in this review and reinforce the importance of standardized assessment tools in occupational health research, particularly when investigating gender differences in musculoskeletal disorders.

3. Discussion

The objective of this systematic review was to analyze how homogeneity criteria are applied in occupational health studies investigating musculoskeletal disorders (MSDs), with particular attention to their implications for women’s health.

Among the five studies included in the systematic review, the representation of female workers varied considerably, ranging from 12% to over 80%. Notably, three studies reported a female participation rate exceeding 40%, with one study (Choobineh et al., 2007) [26] reaching 80% and another (Messing, 2017) [28] indicating a female majority (>50%).

These studies highlight important concerns regarding the musculoskeletal health of women in predominantly blue-collar occupations, such as textile workers and hospital care assistants (HCAs). Women in these roles are frequently exposed to physically demanding tasks, including repetitive movements, awkward postures, and manual handling of loads—factors strongly associated with musculoskeletal disorders (MSDs). In the study by Messing (2017) [28], for example, the analysis was explicitly stratified by work intensity (“light work” vs. “heavy work”), incorporating direct observation and body mapping to document pain distribution. This approach allowed for a nuanced understanding of how workload and postural strain differentially affect women workers, who are often underrepresented or homogenized in occupational health research. Moreover, Choobineh et al. (2007) [26] reported a high prevalence of multi-regional MSDs among female weavers, reinforcing the need for gender-sensitive ergonomic interventions in industrial settings.

Despite being included in mixed-gender samples in other studies, the relatively low representation of women (e.g., 12% in Mayton et al., 2008 [25]) suggests a persistent gap in research specifically designed to assess the musculoskeletal health risks unique to female-dominated professions or to account for sex-related biological and ergonomic differences. These findings underscore the importance of integrating a gender perspective into occupational health studies, both in terms of participant recruitment and in the design of preventive strategies tailored to the specific needs and risks faced by women workers.

Beyond the epidemiological and ergonomic dimensions, an important but often under-discussed aspect emerging from this review is the application of homogeneity criteria in fitness-for-work assessments. All five studies explicitly applied some form of standardization or grouping strategy to ensure internal consistency within the study populations. These criteria—based on exposure type, job category, or functional capacity—serve as proxies for defining work-related risk but also implicitly shape how fitness-for-work decisions could be conceptualized or implemented in clinical occupational practice.

For instance, in Mayton et al. (2008) [25] and Wind et al. (2009) [29], the use of internationally recognized standards (e.g., ISO 2631 [23], EK FCE) enabled the assessment of biomechanical stress and functional performance, both of which are central to determining work suitability. Similarly, Roquelaure et al. (2006) [27] adopted the INRS/Saltsa European consensus criteria, which align with the clinical frameworks used in many occupational health settings for guiding return-to-work or job task modification decisions.

In Messing (2017) [28], the division of workers into “light work” and “heavy work” categories illustrates a direct overlap between research classification and real-world fitness assessments. This stratification reflects the kinds of clinical reasoning often employed by occupational physicians when issuing temporary or permanent fitness judgments, especially for workers with MSDs. Moreover, the incorporation of tools such as body maps and direct observational methods represents an advanced form of functional evaluation that could inform individualized decisions about work placement or restrictions, which are particularly relevant for female workers whose symptoms may be underreported or poorly contextualized.

4. Materials and Methods

A systematic review was conducted using three electronic databases: PubMed, Scopus, and Web of Science, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines [31]. Only primary studies published in English and Italian were considered, with no restrictions on the publication date.

The search strategy was developed using the PICO framework. The population (P) consisted of women working in any context and at any age, the intervention (I) was the use of homogenous criteria to evaluate musculoskeletal disorders in occupational health studies, and the outcome (O) referred to how these criteria were applied to this workforce. No control group (C) was included in the review.

The following search query was employed:

((“clinical guidelines” OR “practice guidelines” OR “recommendations” OR “standardized assessment” OR “occupational physician judgment” OR “occupational health decision making” OR “consensus” OR “uniform criteria”)

AND

(“occupational medicine” OR “occupational health” OR “workplace” OR “workers” OR “working women”)

AND

(“musculoskeletal disorders” OR “musculoskeletal diseases” OR “MSDs” OR “work-related musculoskeletal disorders” OR “musculoskeletal pain”)

AND

(“women” OR “female” OR “gender differences”)).

All retrieved records were screened to identify studies reporting the association between an intervention (I) and an outcome (O). After merging results from the three databases, duplicates were removed. Initial screening based on titles and abstracts was performed using the web-based tool Rayyan [32], which allowed for independent triple-blind review by the researchers to minimize selection bias.

4.1. Inclusion Criteria

The inclusion criteria for the eligible articles were as follows:

(1)

Articles written in English or Italian;

(2)

Working women;

(3)

Working-age population;

(4)

Musculoskeletal Disorders (MSDs);

(5)

Use of homogeneous criteria for occupational fit assessments.

4.2. Exclusion Criteria

All articles that did not strictly meet the “Inclusion Criteria” were excluded.

5. Conclusions

What emerges from this review is that, although not all studies explicitly report on fitness-for-work judgments, the criteria used to ensure population homogeneity mirror many of the clinical criteria used in occupational health practice to determine worker suitability. However, only Messing (2017) [28] explicitly integrates a gender-sensitive approach into these classifications, reinforcing the need to move toward inclusive and differentiated fitness assessments that consider sex and gender not just as covariates but as core determinants of occupational health outcomes. Currently, occupational medicine is mandatory in Italy, in accordance with workplace safety regulations. The law specifies that, in risk assessment, differences in age and gender must be studied and defined.

Our systematic review identified the gap in the literature on this aspect. In Italy, numerous documents [33,34,35,36] have addressed the topic from different perspectives; however, the evolution of the world of work and the technologies connected to it, ongoing digitalization, and increasing occupational disability management policies require a strong effort to update these guidelines for the revised definition of the criteria for the assessment of MSDs. The new interpretation of the concept of work tasks and disability management, the identification of non-regulated risks, and the recent Legislative Decree 62 of 2024 [37] represent a basis for developing a personalized occupational medicine model that identifies, on the one hand, standard fit-to-work judgments with respect to pathologies and anthropometric, age, and sex differences and, on the other hand, an occupational physician’s approach to risk assessment with a view to improving management systems, following the Deming cycle (Plan, Do, Check, Act), analyzing the task in a multidisciplinary way and holistic way, identifying personalized work plans, and preserving the health of both male and female workers, with personalized health promotion projects, which also include the use of Internet of Things (IOT) and Artificial Intelligence (AI), while respecting workers’ dignity and privacy and protecting their right to work.