Work-related musculoskeletal disorders in dockworkers. Systematic review and meta-analysis

Abstract

BACKGROUND:

Dockworkers are exposed to physical overloads that can contribute to the development of musculoskeletal disorders, leading to functional disability and absenteeism.

OBJECTIVE:

to map, critically appraise, and synthesize the available evidence on the prevalence of musculoskeletal diseases associated with port occupational activities.

METHODS:

A comprehensive search was conducted in structured and unstructured databases in August 2023, with no date or language restriction, to identify observational studies evaluating the prevalence of musculoskeletal disorders in dockworkers’ occupational activity. The risk of bias was assessed using validated tools based on the included study designs. Data from studies were pooled in meta-analyses. The certainty of the evidence was assessed using the GRADE approach.

RESULTS:

We identified 12 analytical cross-sectional studies involving 7821 participants in ports of five countries. Most studies (75%) had a moderate methodological quality according to the Joanna Briggs Institute tool. Considering the overall worker categories and any musculoskeletal disorders, the meta-analysis showed a prevalence of 58% (95% Confidence Interval [95% CI] 37% to 78%), with degenerative spinal diseases 42% (95% CI –0.6% to 91%) and low back pain 36% (95% CI 21% to 50%) being the most prevalent conditions. Symptoms were predominantly in foremen and stevedores. The certainty of the evidence was very low.

CONCLUSIONS:

Musculoskeletal disorders seem prevalent among dockworkers, mainly degenerative spinal diseases and low back pain. Studies with greater methodological consistency are still needed to validate these hypotheses and assist in decision-making for implementing preventive and informational policies in maritime port management organizations. PROSPERO registry CRD42021257677.

Keywords

Dockworker occupational diseases cumulative trauma disorders occupational groups prevalence systematic review

1 Introduction

Dockworkers perform numerous occupational activities to ensure the efficient operation of maritime port facilities [1].

Their responsibilities vary depending on the port type, cargo handled, and specific job assignments; however, they often work in physically demanding and potentially risky environments [1, 2].

Despite the introduction of technological equipment for managing loads in recent decades, loading and unloading goods, operating heavy equipment, repetitive force movements, and prolonged exposure to excessive physical demands increase the risk of back pain and other musculoskeletal disorders [1, 2].

Regardless of the function performed, working in seaports requires physical strength and muscular endurance, agility, balance, and constant attention. For these reasons, port authorities and employers should prioritize safety training, equipment maintenance, and ergonomic practices to protect the health and well-being of workers [1, 2].

Musculoskeletal disorders affecting muscles, tendons, ligaments, nerves, and other soft tissues can lead to overuse injuries or chronic physical conditions. Work-related musculoskeletal pain and discomfort could be derived from physical and psychosocial factors, including working load and posture, repetitive movements, and body vibration, associated with work stress, comorbidities, emotional demands, work pace and duration, social conditions, and sociodemographic aspects [3].

The International Labor Organization (ILO) states that musculoskeletal disorders are the second most common occupational disease, representing significant costs to health systems and decreased worker quality of life [4, 5].

Nonetheless, conditions resulting from executing tasks determined by a historically rigid work organization are frequent. In dockworkers, these can result from repeated movements of lifting and moving heavy loads, awkward postures, excessive force, and vibration, mainly causing low back pain, shoulder injuries, carpal tunnel syndrome, knee injuries, and tendinopathies, leading to increased absenteeism rate [5, 6].

There is a growing research area regarding port occupational activities, and mapping this evidence is essential to help in decision-making policies and develop interventions that contribute to strengthening health policies for these workers. Considering the high-risk and adverse environment to which dockworkers are exposed, the prevalence and profile of occupational musculoskeletal diseases have been the object of investigation to identify possible risk factors and plan instructional and preventive strategies. Thus, this systematic review aimed to map, critically appraise, and synthesize the available evidence on the frequency and risk factors of musculoskeletal diseases associated with port occupational activities.

2 Methods

This systematic review was conducted following the recommendations of the Cochrane Handbook for Systematic Reviews of Interventions [7] and the PRISMA guideline (Preferred Reporting Items for Systematic Reviews and Meta-analyses) [8], adapted for observational studies. The review protocol was prospectively registered on the PROSPERO platform (CDR42021257677).

2.1 Eligibility criteria

2.1.1 Types of studies

According to the research question, study designs for inclusion were considered according to the hierarchical order of evidence: comparative (cohort or case-control) and non-comparative observational studies (single-arm cohort and case series), cross-sectional studies (prevalence, survey or analytical) and before-and-after studies that investigated the prevalence of musculoskeletal disorders related to exposure to the port occupational activities. Case reports were excluded.

2.1.2 Types of participants

Adult dockworkers (over 18 years of age) involved in any port occupational activity and diagnosed with any work-related musculoskeletal disorder. Studies that included workers from sectors other than the port environment would only be included if data on port workers were provided separately.

2.1.3 Outcomes of interest

Primary outcomes

Frequency of work-related musculoskeletal disorders.

Anatomical region (diagnosis) of musculoskeletal disorders.

Secondary outcomes

Type of port activity most affected.

Time of work exposure.

Rate of absenteeism.

Loss of productivity (functional capacity).

Quality of life.

The prevalence measures were defined as the number of exposed workers divided by the total number of workers and reported in absolute frequency (percentage).

2.2 Search strategy

A broad and sensitive literature search was performed on August 12, 2023, to identify studies that met the eligibility criteria without restrictions on date, language, or publication status (abstracts or full texts). The following structured search databases were used:

Medical Literature Analysis and Retrieval System Online (Medline), via Pubmed;

Excerpta Medica Database (Embase), via Elsevier;

Biblioteca Virtual em Saúde (BVS);

Cumulative Index to Nursing and Allied Health (CINAHL), EBSCO host;

Physiotherapy Evidence Database (PEDro);

Health Systems Database (https://www.who.int/workforcealliance/knowledge/toolkit/39/en/);

Health Systems Evidence (https://www.healthsystemsevidence.org/);

LILACS (Latin American and Caribbean Health Sciences Literature, via Biblioteca Virtual em Saúde).

Searches were also carried out in unstructured databases and grey literature related to the topic of interest:

Archived bibliographic database (CISDOC), International Labour Organization (ILO/WHO) (https://www.ilo.org/dyn/cisdoc2/cismain.browseSubjects?p_lang=en);

Comprehensive Epidemiologic Data Resource (CEDR) (https://oriseapps.orau.gov/cedr/search.aspx);

Opengrey (https://opengrey.eu/) via DANS Easy Archive (https://easy.dans.knaw.nl/ui/datasets/id/easy-dataset:200362/tab/2);

ProQuest (https://www.proquest.com/).

The manual search was performed through reference lists of relevant articles, search in annals of specific congresses on occupational health, and contact with specialists. Search strategies for all databases are presented in Supplementary material.

2.3 Selection of studies

The selection of studies from the searches was carried out in two stages. In the first stage, two review authors independently selected the titles and abstracts of the references using the Rayyan platform [9]. In the second stage, the studies that met the eligibility criteria were separated for more detailed analysis by reading the full text. A third author was consulted to resolve disagreements.

2.4 Data extraction from included studies

After discussion and consensus on whether or not to include the studies in the review, two independent reviewers extracted data from each included study, using a standardized form previously prepared, containing the following information: year and design of the study, geographic location, sample size, participant baseline aspects, including age and sex, evaluation period, prevalence estimates of musculoskeletal disorders, types of port activities (and other outcomes as assessed by included studies), methodological details and sources of study funding.

2.5 Risk of bias assessment

Two reviewers independently assessed the risk of bias for each study included in the systematic review, and a third reviewer solved any divergence. The risk of bias assessment was planned to be carried out using the appropriate tools for each study design (when identified) as follows: (i) the Risk Of Bias In Non-randomized Studies of Exposure (ROBINS-E) tool for cohort or case-control studies [10], (ii) the Joanna Briggs Institute risk of bias tool for analytical and prevalence cross-sectional studies [11], and (iii) the Quality Assessment Tool for Case Series Studies of the National Institute of Health [12]. For the last two tools, the authors would consider the following categorization according to the agreement with the items: high quality (>80%), moderate quality (50% to 80%) or low quality (<50%).

2.6 Data synthesis

When possible (homogeneous studies and available data), the data from the included studies were pooled and summarized in meta-analyses using a fixed effect model generated by the STATA software version 17.0. The presence of statistical heterogeneity between studies was performed using I² statistics, considering I² values greater than 50% as the existence of significant heterogeneity between studies within the same meta-analysis [7]. Potential causes of substantial cross-study heterogeneity (I² > 50%) were investigated. For the outcomes in which it was not possible to perform meta-analysis, the results of the individual studies were presented in a narrative form (qualitative synthesis).

2.7. Subgroup analysis

Considering the structural changes in port activities in recent years, including the implementation of technologies, regulations, and legislation for the safety and well-being of port workers [13, 14], we carried out an additional analysis separating the results from the included studies published before the 1990 s.

2.8 Certainty of the evidence assessment

Since there is no current guidance for assessing the certainty of the body of evidence in systematic reviews of prevalence studies using the GRADE approach (Grading of Recommendations Assessment, Development, and Evaluation), the assessment for risk or prognosis was used with pertinent adaptations [15]. The certainty of the evidence assessment was conducted for the primary outcomes. It was classified as very low, low, moderate, and high certainty and presented in the Summary of Findings table.

3 Results

3.1 Search results

The search retrieved 621 references. After removing 43 duplicates, 578 studies were selected through titles and abstracts, and 561 did not meet the inclusion criteria. Two of the 17 potentially eligible studies [16, 17] were classified as “awaiting classification” due to the inaccessibility of the full article. These authors were contacted by e-mail unsuccessfully. Therefore, 12 studies (published in 15 articles) were included in this review [18 –32]. The flowchart of the study selection process is shown in Fig. 1.

Fig. 1

PRISMA flowchart of the study selection process.

3.2 Characteristics of the included studies

The studies included in this systematic review were of cross-sectional design, published between 1968 and 2021, and conducted in ports of six countries. The total sample involved 7,821 participants, predominantly male with a mean age of over 40 years, and employees from different port occupational activities, including foreman, stevedoring, cargo checking, cargo repair, vessel surveillance, and vessel general service. One study [30] was found only as a conference abstract (Table 1).

Table 1
Methodological characteristics of the included studies

Study /year Country Study design Population Outcomes of interest (measurement) Data collection period Funding source

Sample (n) Age (years) Male (%) Working time (years)

Almeida 2012 Brazil Analytical cross-sectional 951 >52 100 >21 Frequency of musculoskeletal disorders (medical record) 2000 to 2009 None

Almeida 2016 Brazil Analytical cross-sectional 232 mean 48 100 24 Frequency of musculoskeletal pain (interview) 2000 to 2009 None

Bevilacqua 1990 Italy Analytical cross-sectional 31 mean 36,6 100 13 Frequency of spinal diseases (radiography and clinical examination) NR NR

Carvalho 2016 Brazil Analytical cross-sectional 318 mean 48 100 NR Frequency of musculoskeletal pain and quality of life (NMQ and SF-36) NR NR

Cavalcante 2005 Brazil Analytical cross-sectional 60 mean 41 100 14 Frequency of musculoskeletal pain (interview) 2003 NR

Cezar-Vaz 2016 Brazil Analytical cross-sectional 232 mean 48,7 100 24,3 Frequency of back pain (interview) 2014 Foundation for Research Support of the Rio Grande do Sul (FAPERGS)

Frković 1988 Croatia Analytical cross-sectional 5247 mean 39,7 84,5 NR Frequency of back pain (physical exam) 1986 NR

Patridge 1968 Scotland Analytical cross-sectional 206 25 to 64 100 NR Frequency of musculoskeletal pain (interview), absenteeism rate and functional capacity NR NR

Saito 2018 Brazil Analytical cross-sectional 72 mean 48 100 23 Frequency of cubital tunnel syndrome (elbow pain on palpation and provocative tests) 2016 None

Sedilla 2017 Philippines Analytical cross-sectional 290 NR NR NR Frequency of musculoskeletal disorders (interview) NR Department of Science and Technology

Yoke 1979 Singapore Analytical cross-sectional 100 41 to 50 100 >10 Frequency of lumbar disc degeneration (lumbar spine radiographs) NR NR

Zanatelli 2021 Brazil Analytical cross-sectional 82 mean 42,9 97,6 11,9 Frequency of low back pain (RMD questionnaire), absenteeism rate and quality of life (SF-36 questionnaire) 2018 None

Study /year	Country	Study design	Population	Outcomes of interest (measurement)	Data collection period	Funding source
Almeida 2012	Brazil	Analytical cross-sectional	951	>52	100	>21	Frequency of musculoskeletal disorders (medical record)	2000 to 2009	None
Almeida 2016	Brazil	Analytical cross-sectional	232	mean 48	100	24	Frequency of musculoskeletal pain (interview)	2000 to 2009	None
Bevilacqua 1990	Italy	Analytical cross-sectional	31	mean 36,6	100	13	Frequency of spinal diseases (radiography and clinical examination)	NR	NR
Carvalho 2016	Brazil	Analytical cross-sectional	318	mean 48	100	NR	Frequency of musculoskeletal pain and quality of life (NMQ and SF-36)	NR	NR
Cavalcante 2005	Brazil	Analytical cross-sectional	60	mean 41	100	14	Frequency of musculoskeletal pain (interview)	2003	NR
Cezar-Vaz 2016	Brazil	Analytical cross-sectional	232	mean 48,7	100	24,3	Frequency of back pain (interview)	2014	Foundation for Research Support of the Rio Grande do Sul (FAPERGS)
Frković 1988	Croatia	Analytical cross-sectional	5247	mean 39,7	84,5	NR	Frequency of back pain (physical exam)	1986	NR
Patridge 1968	Scotland	Analytical cross-sectional	206	25 to 64	100	NR	Frequency of musculoskeletal pain (interview), absenteeism rate and functional capacity	NR	NR
Saito 2018	Brazil	Analytical cross-sectional	72	mean 48	100	23	Frequency of cubital tunnel syndrome (elbow pain on palpation and provocative tests)	2016	None
Sedilla 2017	Philippines	Analytical cross-sectional	290	NR	NR	NR	Frequency of musculoskeletal disorders (interview)	NR	Department of Science and Technology
Yoke 1979	Singapore	Analytical cross-sectional	100	41 to 50	100	>10	Frequency of lumbar disc degeneration (lumbar spine radiographs)	NR	NR
Zanatelli 2021	Brazil	Analytical cross-sectional	82	mean 42,9	97,6	11,9	Frequency of low back pain (RMD questionnaire), absenteeism rate and quality of life (SF-36 questionnaire)	2018	None

n: number of participants; NR: not reported; NMQ: The Nordic Musculoskeletal Questionnaire; SF-36: Short-Form Health Survey; RMDQ: Roland Morris Disability Questionnaire.

3.3 Risk of bias assessment

Given the study design of the included studies, the risk of bias was assessed using the Joanna Briggs Institute (JBI) tool for analytical cross-sectional studies, and 75% (9/12) presented a moderate rate. Table 2 shows the judgment of each study considering each tool domain. Item 3 of the JBI tool was judged as “not performed” for studies that retrospectively collected data through the participants’ medical records. Items 5 and 6 were classified as “not performed” for almost all included studies, as they did not consider the identification and strategies to deal with possible confounding factors related to port activities (exposure) and the occurrence of musculoskeletal disorders. One study [30] was classified as “uncertain” for most evaluated items due to the lack of information.

Table 2
Methodological quality assessment of the included studies

Joanna Briggs Institute for analytical cross-sectional studies

Included studies 1. Were the criteria for inclusion in the sample clearly defined? 2. Were the study subjects and the setting described in detail? 3. Was the exposure measured validly and reliably? 4. Were objective, standard criteria used for measurement of the condition? 5. Were confounding factors identified? 6. Were strategies to deal with confounding factors stated? 7. Were the outcomes measured validly and reliably? 8. Was appropriate statistical analysis used? Total

Almeida 2012 Yes Yes No Yes No No Yes Yes 5/8 62,5%

Almeida 2016 Yes Yes Yes Yes No No Yes Yes 6/8 75%

Bevilacqua 1990 No Yes Yes Yes No No Yes No 4/8 50%

Carvalho 2016 No Yes Yes Yes No No Yes Yes 5/8 62,5%

Cavalcanti 2005 Yes Yes Yes Yes No No No No 4/8 50%

Cezar-Vaz 2016 Yes Yes Yes Yes Yes No Yes Yes 7/8 87,5%

Partridge 1968 Yes No Unclear Yes No No No Yes 3/8 37,5%

Frković 1988 No Yes No Yes No No No Unclear 2/8 25%

Saito 2018 Yes Yes Yes Yes No No Yes Yes 6/8 75%

Sedilla 2017 Yes Unclear Unclear Yes Unclear Unclear No Unclear 2/8 25%

Yoke 1979 Yes No Yes Yes No No Yes Yes 5/8 62,5%

Zanatelli 2021 Yes Yes Yes Yes No No Yes Yes 6/8 75%

Joanna Briggs Institute for analytical cross-sectional studies
Almeida 2012	Yes	Yes	No	Yes	No	No	Yes	Yes	5/8 62,5%
Almeida 2016	Yes	Yes	Yes	Yes	No	No	Yes	Yes	6/8 75%
Bevilacqua 1990	No	Yes	Yes	Yes	No	No	Yes	No	4/8 50%
Carvalho 2016	No	Yes	Yes	Yes	No	No	Yes	Yes	5/8 62,5%
Cavalcanti 2005	Yes	Yes	Yes	Yes	No	No	No	No	4/8 50%
Cezar-Vaz 2016	Yes	Yes	Yes	Yes	Yes	No	Yes	Yes	7/8 87,5%
Partridge 1968	Yes	No	Unclear	Yes	No	No	No	Yes	3/8 37,5%
Frković 1988	No	Yes	No	Yes	No	No	No	Unclear	2/8 25%
Saito 2018	Yes	Yes	Yes	Yes	No	No	Yes	Yes	6/8 75%
Sedilla 2017	Yes	Unclear	Unclear	Yes	Unclear	Unclear	No	Unclear	2/8 25%
Yoke 1979	Yes	No	Yes	Yes	No	No	Yes	Yes	5/8 62,5%
Zanatelli 2021	Yes	Yes	Yes	Yes	No	No	Yes	Yes	6/8 75%

3.4 Synthesis of the results from included studies

The prevalence of participants diagnosed with musculoskeletal disorders ranged between 6.9% and 100% of the samples analyzed in the included studies. Regarding the professional category, seven studies separately described the number of participants evaluated in each subgroup, and musculoskeletal disorders were predominant in foremanship, stevedoring, and cargo checking (Table 3).

Table 3
Frequency of musculoskeletal disorders related to the portworkers professional category

Study /Year MD diagnosis (n/N, %) Dockworkers professional category (n, %)

Foreman Stevedore Cargo checking Cargo repairman Vessel watchman Vessel general services

Almeida 2012 152/951 (15.8%) 73 (48%) 57 (37.5%) 9 (5.9%) 1 (0.7%) 9 (5.9%) 2 (1.3%)

Almeida 2016 232/232 (100%) 136 (58,6%) 96 (41,4%)

Bevilacqua 1990 29/31 (93.5%) NR NR NR NR NR NR

Carvalho 2016 118/318 (37.4%) 173 (54.4%) 95 (29.9%) 20 (6.3) 7 (2.2%) 13 (4.1%) 10 (3.1%)

Cavalcante 2005 58/60 (96.7%) 60 (100%) – – – – –

Cezar-Vaz 2018 232/232 (100%) 136 (58.6%) 79 (34.1%) 17 (7.3%) – – –

Frković 1988 1265/5247 (24.1%) NR NR NR NR NR NR

Partridge 1968 89/206 (43.2%) NR NR NR NR NR NR

Saito 2018 5/72 (6.9%) 27 (37.5%) 42 (58.3%) 1 (1.4%) – 1 (1.4%) –

Sedilla 2017 NR NR NR NR NR NR NR

Yoke 1979 98/100 (98%) NR NR NR NR NR NR

Zanatelli 2021 14/82 (17.1%) 14 (17.1%) 21 (25.6%) 11 (13.4%) 1 (1.2%) 1 (1.2%) 2 (2.4%)

Study /Year	MD diagnosis (n/N, %)	Dockworkers professional category (n, %)
Almeida 2012	152/951 (15.8%)	73 (48%)	57 (37.5%)	9 (5.9%)	1 (0.7%)	9 (5.9%)	2 (1.3%)
Almeida 2016	232/232 (100%)	136 (58,6%)	96 (41,4%)
Bevilacqua 1990	29/31 (93.5%)	NR	NR	NR	NR	NR	NR
Carvalho 2016	118/318 (37.4%)	173 (54.4%)	95 (29.9%)	20 (6.3)	7 (2.2%)	13 (4.1%)	10 (3.1%)
Cavalcante 2005	58/60 (96.7%)	60 (100%)	–	–	–	–	–
Cezar-Vaz 2018	232/232 (100%)	136 (58.6%)	79 (34.1%)	17 (7.3%)	–	–	–
Frković 1988	1265/5247 (24.1%)	NR	NR	NR	NR	NR	NR
Partridge 1968	89/206 (43.2%)	NR	NR	NR	NR	NR	NR
Saito 2018	5/72 (6.9%)	27 (37.5%)	42 (58.3%)	1 (1.4%)	–	1 (1.4%)	–
Sedilla 2017	NR	NR	NR	NR	NR	NR	NR
Yoke 1979	98/100 (98%)	NR	NR	NR	NR	NR	NR
Zanatelli 2021	14/82 (17.1%)	14 (17.1%)	21 (25.6%)	11 (13.4%)	1 (1.2%)	1 (1.2%)	2 (2.4%)

MD: musculoskeletal disorders; n: number of participants diagnosed with musculoskeletal conditions; N: number of participants in the study; NR: not reported.

Table 4 presents the numerical data results of the included studies considering the prevalence of different musculoskeletal disorders concerning the overall population and the subgroups by professional category. Foremen and stevedores were the workers’ category most affected by musculoskeletal disorders, mainly low back pain (11.6% to 45.0%). Considering the overall population, there was a predominance of diagnoses of low back pain (28.0% to 69.8%), back pain (3.3% to 60%), and tendinopathies (15.7% to 20.7%).

Table 4

Prevalence of musculoskeletal diseases regarding the professional category and the overall population of dockworkers

Musculoskeletal disorders	Professional category						Total
Foreman	Stevedore	Cargo checking	Cargo repairman	Vessel watchman	Vessel general services
Low back pain
Almeida 2012	35/152 (23.0%)	24/152 (15.7%)	8/152 (5.2%)	1/152 (0.7%)	1/152 (0.7%)	1/152 (0.7%)	70/152 (46.1%)
Almeida 2016	27/232 (11.6%)	50/232 (21.6%)					77/232 (33.2%)
Cavalcante 2005	–	27/60 (45.0%)	–	–	–	–	27/60 (45.0%)
Cezar-Vaz 2018	96/232 (41.4%)	58/232 (25.0%)	8/232 (3.4%)	–	–	–	162/232 (69.8%)
Partridge 1968	61/206 (29.6%)
Sedilla 2017	–	–	–	–	–	–	168/290 (58.0%)
Zanatelli 2021	–	16/82 (19.0%)	–	7/82 (9.1%)	–	–	23/82 (28.0%)
Osteoarthritis
Almeida 2012	11/152 (7.3%)	6/152 (4.0%)	–	–	–	–	17/152 (11.2%)
Almeida 2016	22/232 (9.5%)	41/232 (17.7%)					63/232 (27.2%)
Frković 1988	–	–	–	–	–	–	183/5247 (3.5%)
Partridge 1968	–	–	–	–	–	–	44/206 (21.3%)
Back pain
Almeida 2012	2/152 (1.3%)	3/152 (2.0%)	–	–	–	–	5/152 (3.3%)
Cezar-Vaz 2018	66/232 (28.4%)	44/232 (19.0%)	8/232 (3.4%)	–	–	–	118/232 (50.9%)
Sedilla 2017	–	–	–	–	–	–	174/290 (60.0%)
Degenerative spinal diseases
Carvalho 2016	–	–	–	–	–	–	28/318 (9.1%)
Frković 1988	–	–	–	–	–	–	1082/5247 (20.6%)
Yoke 1979	–	–	–	–	–	–	98/100 (98%)
Tendinopathy
Almeida 2012	16/152 (10.5%)	6/152 (3.9%)	1/152 (0.7%)	–	7/152 (4.6%)	–	30/152 (19.7%)
Almeida 2016	30/232 (12.9%)	38/232 (16.4%)					48/232 (20.7%)
Carvalho 2016	–	–	–	–	–	–	49/318 (15.7%)
Bursitis
Almeida 2012	2/152 (1.3%)	5/152 (3.3%)	–	–	–	–	7/152 (4.6%)
Almeida 2016	16/232 (6.9%)	22/232 (9.5%)					38/232 (16.4%)
Carvalho 2016	–	–	–	–	–	–	18/318 (5.7%)
Epicondylitis
Almeida 2012	7/152 (4.6%)	5/152 (3.3%)	1/152 (0.7%)	–	–	–	13/152 (8.6%)
Almeida 2016	10/232 (4.3%)	11/232 (4.7%)					21/232 (9.1%)
Synovitis and tenosynovitis
Almeida 2012	1/152 (0.7%)	2/152 (1.3%)	–	–	–	–	3/152 (2.0%)
Almeida 2016	3/232 (1.3%)	6/232 (2.6%)					9/232 (3.9%)
Trigger finger
Almeida 2012	–	1/152 (0.7%)	–	–	–	–	1/152 (0.7%)
Almeida 2016	5/232 (2.2%)	10/232 (4.3%)					15/232 (6.5%)
Arthralgia
Almeida 2012	1/152 (0.7%)	2/152 (1.3%)					1/152 (0.7%)
Cavalcanti 2005	–	17/60 (28.3%)					17/60 (28.3%)
Neck pain
Almeida 2012	9/152 (5.9%)	7/152 (4.6%)	–	–	2/152 (1.3%)	1/152 (0.7%)	19/152 (12.5%)
Cubital tunnel syndrome
Saito 2018	–	–	–	–	–	–	5/72 (6.9%)
Spinal disorders (scoliosis, hyperkyphosis and hyperlordosis)
Bevilacqua 1990	–	–	–	–	–	–	29/31 (93.5%)
Muscle pain
Cavalcanti 2005	–	14/60 (23.3%)	–	–	–	–	14/60 (23.3%)

Given the homogeneity between studies, meta-analyses of prevalence were performed for the population of all dockworkers categories, considering the musculoskeletal diseases most commonly identified in the included studies. The results showed that the prevalence estimate of any musculoskeletal disorder was 58% (95% Confidence Interval [95% CI] 37% to 78%, n = 2,292 in 7,531 participants, eleven studies) (Fig. 2). The prevalence rate of most common conditions was: 42% (95% CI –0.6% to 91%, 1,208 in 5,665 participants, three studies) for degenerative spinal diseases (Fig. 3) and 36% (95% CI 21% to 50%, 449 in 1,254 participants, seven studies) for low back pain (Fig. 4). However, the certainty

Fig. 2

Meta-analysis of the frequency of musculoskeletal disorders related to port occupational activities.

Fig. 3

Meta-analysis of the frequency of degenerative spinal diseases related to port occupational activities.

Fig. 4

Meta-analysis of the frequency of low back pain related to port occupational activities.

of the evidence assessed by the GRADE approach was classified as very low due to the methodological limitations, small sample size, and wide confidence interval (Table 5), indicating that we are unconfident regarding these prevalence estimates.

Table 5

Summary of findings table –GRADE approach

of studies	Certainty assessment						Effect			Certainty
	Study design	Risk of bias	Inconsistency	Indirectness	Imprecision	Other considerations	of events	of individuals	Rate (95% CI)
11	observational studies	serious^a	very serious^a	not serious	not serious	none	2292	7531	event rate 58 per 100 (37 to 78)	Very low
3	observational studies	serious^a	very serious^b	not serious	serious^c	none	1208	5665	event rate 42 per 100 (–0.06 to 91)	Very low
7	observational studies	serious^a	very serious^b	not serious	serious^c	none	449	1254	event rate 36 per 100 (21 to 50)	Very low

Explanations: a. Methodological limitations (downgraded one level). b. Substantial heterogeneity (downgraded two levels). c. Wide confidence interval (downgraded one level).

Meta-analyses for other musculoskeletal disorders demonstrated the following prevalence:

Arthralgia: 14% (95% CI –13% to 41%, 18 in 212 participants, two studies [20, 23]);

Tendinopathy: 13% (95% CI –1% to 24%, 127 in 1,501 participants, three studies [18, 20, 22);

Osteoarthritis: 11% (95% CI 7% to 15%, 307 in 6,636 participants, four studies 18, 20, 27, 28]);

Epicondylitis: 9% (95% CI 6% to 12%, 34 in 384 participants, two studies [19, 21]);

Synovitis and tenosynovitis: 3% (95% CI 1% to 5%, 12 in 384 participants, two studies [20, 23]);

Trigger finger: 3% (95% CI –2% to 9%, 18 in 384 participants, two studies [20, 23]).

It is important to note that, as expected in the prevalence of exposure, substantial heterogeneity was detected in all meta-analyses using the I² statistic (I² > 97%), and some facts may explain it, such as the discrepancy in the disease prevalence measures used by the studies, methodological and work tasks differences and the small number of events in some studies.

3.4.1 Subgroup analysis

The results of three studies [27 , 31], published between 1968 and 1988, were reported separately. The data provided by these studies refer only to any port professional, without specification by category, and the prevalence of any musculoskeletal disorder varied between 24.1% and 98%. One study [28] estimated that low back pain affects 29.6% of port workers. Furthermore, there was a frequency of 3.5% to 21.3% of osteoarthritis cases [27, 28] and 20.6% to 98% of spine degenerative diseases [27, 31].

3.4.2 Additional information on study results

Three studies [18 –20] explained a relationship between age group, length of professional activity, and the prevalence of musculoskeletal diseases. The studies reported a positive association between symptom intensity and the highest age group (p = 0.04) and low back diagnosis pain and time of work (p = 0.033), indicating that the longer the working time, the greater the perception of the intensity of the symptoms. The category with working time over 21 years was the most prevalent.

Another variable analyzed by the included studies was the physical activity practice; two studies [22, 32] showed that a sedentary lifestyle could be associated with a risk factor for the occurrence of work-related musculoskeletal disorders (p = 0.0005).

One study [22] assessed workers’ quality of life using the SF-36 questionnaire. A relationship was observed between work-related musculoskeletal disorders and the following questionnaire items: functional capacity (p < 0.00), physical aspects (p < 0.00), social aspects (p < 0.00), pain (p < 0.00), and vitality (p < 0.00). Only emotional aspects (p < 0.26), mental health (p < 0.07), and general health status (p < 0.10) did not show a significant association with work-related musculoskeletal symptoms.

Finally, an included study [32] evaluated the absenteeism rate and observed that 19.7% of the cases complained of occupational low back pain. As expected, physical activity positively influenced reported quality of life, directly related to improved physical vitality and better performance at work. Another study [28] observed that the participants lost a mean of 110 weeks a year, and the primary cause of reduced functional capacity and loss of employment was low back pain, corresponding to 75 weeks.

4 Discussion

Dockworkers are often engaged in physically demanding and repetitive tasks, which can contribute to the development of musculoskeletal problems. The nature of their work, which involves loading and unloading cargo, manipulating containers, securing freight, and operating cranes, can place massive strain on their musculoskeletal system [5, 33]. However, few studies focus on these workers and mapping and synthesizing the available evidence on its prevalence and associated risk factors can help develop and adopt preventive measures for workers’ health. The results of this systematic review and meta-analysis derived from 12 cross-sectional showing that musculoskeletal disorders seem to have a prominent prevalence (58%) in dockworkers, probably given the physical overload exposure, and it may be increased in a population with higher age, length of professional activity and sedentary lifestyle. The most prevalent diagnoses were degenerative spinal diseases (42%) and low back pain (36%); the other conditions occurred in less than 15% of the analyzed dockworkers. It is important to mention that given the methodological limitations, imprecision in the estimated effects, and substantial heterogeneity (inconsistency) between included studies, the certainty of this body of evidence was classified as very low according to the GRADE approach, indicating little confidence in the estimated prevalence.

The cross-sectional studies identified were conducted in maritime ports of five countries, and all the analyzed categories of dockworkers (foreman, stevedore, cargo checker, cargo repairman, vessel watchman, and vessel general services) had some degree of musculoskeletal symptoms, with foreman and stevedore presenting a higher frequency of conditions.

Previous studies have reported that the most significant risk of musculoskeletal and occupational traumatic injuries in seaports is associated with loading and unloading procedures, the transportation, handling, and storage of goods on docks, and low back pain is associated with high rates of absenteeism, with symptoms disabling [5 , 33].

Hence, preventing and managing work-related musculoskeletal disorders in dockworkers requires implementing ergonomic strategies and promoting a safe working environment. This involves providing comprehensive training on proper lifting techniques, encouraging the use of mechanical aids and assistive devices, organizing work tasks to minimize repetitive movements, implementing regular rest breaks, and promoting physical fitness and overall well-being. Thus, early detection and intervention are essential to mitigate the impacts of these disorders on dockworkers’ quality of life [3 , 33].

According to the risk of bias assessment, performed using the Joanna Briggs Institute analytical cross-sectional study risk of bias tool [11], most included studies were classified as moderate quality. However, only one of the studies analyzed the confounding factors associated with the association between occupational activities and musculoskeletal diseases, such as physical exercise practice and analgesic medication.

No similar systematic reviews have been found in the literature so far. Thus, it is necessary to consider that systematic reviews and meta-analyses of prevalence studies present particular challenges due to inherent biases in the design and heterogeneity between studies. Nonetheless, the recommended methodology for conducting this type of systematic review is incipient and still developing. Thus, efforts are needed on the part of the scientific community to establish a standardized, comprehensive, and transparent methodological framework for systematic reviews of prevalence, for the production of reliable estimates on environmental and occupational exposure factors and the prevalence of diseases in different scenarios and their potential sources of variability [34, 35].

The present systematic review has some limitations regarding the adaptation of methodological guidance and the probable heterogeneity between study populations, which include many port work activities and different worker characteristics such as age and time of exposure. Also, most of the included studies conducted a retrospective analysis, which can lead to measurement bias.

In this context, it is crucial to highlight possible confounding factors relating to the nature of the work and the changes in port work practice automation over the last few decades, as well as adaptations in legal and social conditions and worker health and safety legislation. Since the ILO Dock Work Convention (No. 137) of 1973, there has been increased attention to cargo management and systems training, ensuring work efficiency and preventing occupational injuries and illnesses in port work activities. These health and safety recommendations determine guidelines for policies and procedures, but these regulations can differ between countries, labor conditions, and port technology status [14].

It is noted that the occupational problems that affect dockworkers have been little investigated, which inhibit informational practice and preventive behaviors, leading to a potential increase in reported injuries and the consequent progression of absenteeism, leaves, and occupational diseases. The field of workers’ health brings a series of advances regarding thinking about the work-health relationship insofar as it was able to overcome certain limits present in the areas of occupational medicine and occupational health. In this way, raising reliable data regarding the threats of occupational diseases in dockworkers, in line with bioethical concepts, makes establishing preventive and informative policies gain scientific and moral support, bringing even greater effectiveness to the data that emerged. Dockworkers can perform their tasks effectively and maintain a sustainable and productive work environment by prioritizing health and safety [36].

5 Conclusion

Based on very low certainty evidence, musculoskeletal disorders seem prevalent among dockworkers from maritime ports, mainly degenerative spinal diseases and low back pain. Studies with greater methodological consistency are still needed to validate these hypotheses and assist in decision-making for implementing preventive and informational policies in maritime port management organizations.

Ethical approval

Not applicable.

Informed consent

Not applicable.

Conflict of interest

The authors report there are no competing interests to declare.

Footnotes

Acknowledgments

Not applicable.

Funding

No funding sources.

Author contributions

All authors contributed to the study’s conception and design. Material preparation, data collection, and analysis were performed by GRC, KMMS, GMS, MLLG, EMS, RLP, and ALCM. The first draft of the manuscript was written by GRC, ALCM, RR, SKB, and GDM, and all authors commented on previous versions. All authors read and approved the final manuscript.

The supplementary file is available from:

References

ILO code of practice: Safety and health in ports (Revised 2016). International Labour Office, Geneva; 2018 [accessed July 25, 2023]. Available from: https://www.imo.org/en/OurWork/Facilitation/Pages/ILOCode-Default.aspx.

Taibi

, Metzler

, Bellingrath

, Müller

. A systematic overview on the risk effects of psychosocial work characteristics on musculoskeletal disorders, absenteeism, and workplace accidents, Appl Ergon. 2021;95:103434. doi: 10.1016/j.apergo.2021.103434.

Krishnan

, Raju

, Shawkataly

. Prevalence of Work-Related Musculoskeletal Disorders: Psychological and physical risk factors, Int J Environ Res Public Health. 2021;18(17):9361. doi: 10.3390/ijerph18179361.

Niu

. Ergonomics and occupational safety and health: An ILO perspective, Appl Ergon. 2010;41(6):744–53. doi: 10.1016/j.apergo.2010.03.004.

Rabiei

, Malakoutikhah

, Vaziri

, Sahlabadi

. The Prevalence of musculoskeletal disorders among miners around the world: A systematic review and meta-analysis, Iran J Public Health. 2021;50(4):676–88. doi: 10.18502/ijph.v50i4.5992.

Barbieri

, Sabatini

, Graziosi

, Severi

, Mancini

, Violante

. I rischi per la salute e la sicurezza nel lavoro portuale: Aggiornamento della revisione narrativa della letteratura [Occupational safety and health risks in seaport: An update of narrative review], G Ital Med Lav Ergon. 2019;41(4):294–8.

Higgins

JPT

, Thomas

, Chandler

, Cumpston

, Li

, Page

, Welch

(editors) Cochrane Handbook for Systematic Reviews of Interventions version 6.3 (updated February 2022). Cochrane [Accessed on July 25, 2023].

Page

, McKenzie

, Bossuyt

, Boutron

, Hoffmann

, Mulrow

, Shamseer

, Tetzlaff

, Akl

, Brennan

, Chou

, Glanville

, Grimshaw

, Hróbjartsson

, Lalu

, Li

, Loder

, Mayo-Wilson

, McDonald

, McGuinness

, Stewart

, Thomas

, Tricco

, Welch

, Whiting

, Moher

. The PRISMA statement: An updated guideline for reporting systematic reviews, BMJ. 20202021;372:n71. doi: 10.1136/bmj.n71.

Ouzzani

, Hammady

, Fedorowicz

, Elmagarmid

. Rayyan-a web and mobile app for systematic reviews, Syst Rev. 2016;5(1):210. doi: 10.1186/s13643-016-0384-4.

10.

Higgins

, Morgan

, Rooney

, et al. Risk of bias in non-randomized studies –of exposure (ROBINS-E). Launch version, June 20, 2023.https://www.riskofbias.info/welcome/robins-e-tool [Accessed on July 25, 2023].

11.

Moola

, Munn

, Tufanaru

, et al. Chapter 7: Systematic reviews of etiology and risk. In: Aromataris E, Munn Z (Editors). Joanna Briggs Institute Reviewer’s Manual. The Joanna Briggs Institute; 2017. Available from:https://reviewersmanual.joannabriggs.org/[Accessed on July 25, 2023].

12.

Quality Assessment Tool for Case Series studies. National Heart, Lung, and Blood Institute; 2013. Available from: https://www.nhlbi.nih.gov/health-topics/study-quality-assessment-tools[Accessed on February 16, 2024].

13.

Information System on International Labour Standards. C137 - Dock Work Convention, 1973 (No. 137). Available from: https://www.ilo.org/dyn/normlex/en/f?p=NORMLEXPUB:12100:0::NO:12100:P12100_INSTRUMENT_ID:312282:NO [Accessed on February 16, 2024].

14.

Information System on International Labour Standards. C152 –Occupational Safety and Health (Dock Work) Convention, 1979 (No. 152). Available from: https://www.ilo.org/dyn/normlex/en/f?p=NORMLEXPUB:12100:0::NO::P12100_ILO_CODE:C152.

15.

Foroutan

, Guyatt

, Zuk

, Vandvik

, Alba

, Mustafa

, Vernooij

, Arevalo-Rodriguez

, Munn

, Roshanov

, Riley

, Schandelmaier

, Kuijpers

, Siemieniuk

, Canelo-Aybar

, Schunemann

, Iorio

. GRADE Guidelines Use of GRADE for the assessment of evidence about prognostic factors: Rating certainty in identification of groups of patients with different absolute risks, J Clin Epidemiol. 2020;121;62–70. doi: 10.1016/j.jclinepi.2019.12.023.

16.

Piccinni

, Marchì

, Lorusso

, Magarotto

. Prevalenza di spondilopatie tra i gruisti del porto di Venezia [The prevalence of spondylopathies among the crane operators in the port of Venice], Med Lav. 1992;83(2):146–9.

17.

Waśkiewicz

. The effect of heavy work on the musculoskeletal system of dockers, Bull Inst Marit Trop Med Gdynia. 1996;47(1-4):25–32.

18.

Almeida

, Cezar-Vaz

. Scientific evidence of dockworker illness to nursing clinical reasoning, Rev Esc Enferm USP. 2016;50(2):346–54.https://dx-doi-org.web.bisu.edu.cn/10.1590/S0080-623420160000200022.

19.

Almeida de

MCV

, Cezar-Vaz

, Rocha

, Cardoso

. Trabalhador portuário: perfil de doenças ocupacionais diagnosticadas em serviço de saúde ocupacional, Acta Paulista de Enfermagem. 2012;25(2):270–6.https://doi.org/10.1590/S0103-21002012000200018.

20.

Almeida

, Cezar-Vaz

, Soares

, Silva

. The prevalence of musculoskeletal diseases among casual dock workers, Rev Lat Am Enfermagem. 2012;20(2):243–50.English, Portuguese, Spanish. 10.1590/s0104-11692012000200005.

21.

Bevilacqua

, Pupp

, Magnavita

, Callopoli

. Esposizione a vibrazioni a bassa frequenza ed affezioni del rachide nei lavoratori portuali [Exposure to low-frequency vibrations and spinal diseases in dock workers], Clin Ter. 1990;135(6):475–7.

22.

de Carvalho

, Schmidt

, Soares

. Musculoskeletal disorders and their influence on the quality of life of the dockworker: A cross-sectional study, Work. 2016;53(4):805–12. doi: 10.3233/WOR-162249.

23.

Cavalcante

FFG

, Gomes

ACN

, Nogueira de

FRA

, et al. Estudo sobre os riscos da profissão de estivador do Porto do Mucuripe em Fortaleza, Ciênc saúde coletiva [Internet]. 2005;10:101–10. https://doi.org/10.1590/S1413-81232005000500013.

24.

Cezar-Vaz

, Bonow

, Almeida

, Sant’Anna

, Cardoso

. Workload and associated factors: A study in maritime port in Brazil, Rev Lat Am Enfermagem–2016;24:e2837. doi: 10.1590/1518-8345.1347.2837.

25.

Cezar-Vaz

, Bonow

, Xavier

, Vaz

, Cardoso

, Mello

MCVA

, Costa

VZD

, Sant’Anna

. Prevalence of low back pain and Dorsalgia and associated factors among casual dockworkers, Int J Environ Res Public Health. 2018;15(10):2310. doi: 10.3390/ijerph15102310.

26.

Cezar-Vaz

, Bonow

, Xavier

, Vaz

, Cardoso

, Mello

MCVA

, Costa

VZD

, Sant’Anna

. Prevalence of low back pain and Dorsalgia and associated factors among casual dockworkers, Int J Environ Res Public Health. 2018;15(10):2310. doi: 10.3390/ijerph15102310.

27.

Frković

, Škrobonja

, Vukelić

. Vertebropatije luckih radnika, Arch hig rada toksikol. 1988;39(2):235–40.

28.

Partridge

, Duthie

. Rheumatism in dockers and civil servants, A comparison of heavy manual and sedentary workers. Ann Rheum Dis. 1968;27(6):559–68. doi: 10.1136/ard.27.6.559.

29.

Saito

, Yano

, Angelini

, Matos

, Guimarães

, Angelini

. Prevalence of cubital tunnel syndrome among dock workers, Saint Sebastian, São Paulo, Brazil, Rev Bras Med Trab. 2018;16(3):270–6. doi: 10.5327/Z1679443520180265.

30.

Sedilla

, Matias

. Prevalence, Severity, and risk factors of work-related musculoskeletal disorders among stevedores in a Philippine break-bulk port terminal, Advances in Intelligent Systems and Computing. 2017;90–100.

31.

Yoke

, Ann

. Study of lumbar disc pathology among a group of dockworkers, Ann Acad Med Singa. 1979;8(1):81–5.

32.

Zanatelli

, Guimarães

, Storte

, Velloso

, Emidio

, Peruzzetto

, Bastos

PAS

. Prevalence of low back pain in Port of Santos workers, Rev Bras Med Trab. 2021;19(2):173–80.

33.

Barbieri

, Sabatini

, Graziosi

, Severi

, Mancini

, Violante

. I rischi per la salute e la sicurezza nel lavoro portuale: revisione narrativa della letteratura [Occupational safety and health risks in dock work: A narrative literature review], Med Lav. 2014;105(6):413–34.

34.

Maciel

, Lopes

, Gonçalves

. Ports modernization and its influence on trade unions, Work. 2012;41(Suppl 1)5775–7. doi: 10.3233/WOR-2012-0948-5775.

35.

Migliavaca

, Stein

, Colpani

, Barker

, Munn

, Falavigna

Prevalence Estimates Reviews –Systematic Review Methodology Group (PERSyst) How are systematic reviews of prevalence conducted? A methodological study, BMC Med Res Methodol. 2020;20(1):96. doi: 10.1186/s12874-020-00975-3.

36.

Pega

, Momen

, Bero

, Whaley

. Towards a framework for systematic reviews of the prevalence of exposure to environmental and occupational risk factors, Environ Health. 2022;21(1):64.https://doi.org/10.1186/s12940-022-00878-4.

37.

Motter

, Silva

, Santos

. Opportunities to enhance collective activity to meet the demands of a task: A case of job rotation among port workers, Work. 2021;69(1):283–93. doi: 10.3233/WOR-213477PMID: 33998588.

Joanna Briggs Institute for analytical cross-sectional studies
Included studies	1. Were the criteria for inclusion in the sample clearly defined?	2. Were the study subjects and the setting described in detail?	3. Was the exposure measured validly and reliably?	4. Were objective, standard criteria used for measurement of the condition?	5. Were confounding factors identified?	6. Were strategies to deal with confounding factors stated?	7. Were the outcomes measured validly and reliably?	8. Was appropriate statistical analysis used?	Total
Almeida 2012	Yes	Yes	No	Yes	No	No	Yes	Yes	5/8 62,5%
Almeida 2016	Yes	Yes	Yes	Yes	No	No	Yes	Yes	6/8 75%
Bevilacqua 1990	No	Yes	Yes	Yes	No	No	Yes	No	4/8 50%
Carvalho 2016	No	Yes	Yes	Yes	No	No	Yes	Yes	5/8 62,5%
Cavalcanti 2005	Yes	Yes	Yes	Yes	No	No	No	No	4/8 50%
Cezar-Vaz 2016	Yes	Yes	Yes	Yes	Yes	No	Yes	Yes	7/8 87,5%
Partridge 1968	Yes	No	Unclear	Yes	No	No	No	Yes	3/8 37,5%
Frković 1988	No	Yes	No	Yes	No	No	No	Unclear	2/8 25%
Saito 2018	Yes	Yes	Yes	Yes	No	No	Yes	Yes	6/8 75%
Sedilla 2017	Yes	Unclear	Unclear	Yes	Unclear	Unclear	No	Unclear	2/8 25%
Yoke 1979	Yes	No	Yes	Yes	No	No	Yes	Yes	5/8 62,5%
Zanatelli 2021	Yes	Yes	Yes	Yes	No	No	Yes	Yes	6/8 75%