Prevalence of low back pain in Port of Santos workers

Abstract

INTRODUCTION:

Low back pain is a common symptom among the general population and among manual workers, contributing to high rates of absenteeism and a decrease in overall quality of life.

OBJECTIVES:

To determine the prevalence of low back pain in Port of Santos workers, its influence on overall quality of life, physical activity level, and associated absenteeism rate.

METHODS:

This cross-sectional prevalence study was based on prospective data collection.

RESULTS:

Eighty-two port workers were interviewed, 97.6% were male, and mean age was 42.9 years. Ethnically, 37.8% reported being brown. Most had completed high school. Longshoreman was the most common occupation, followed by foreman, tallyman, and others. A 44-hour workweek was the most frequent (31.3%), and over 85% of workers reported not working overtime. Most of them were not paid on a production basis. Formal employment, according to Brazilian Labor Law, was 70.7%, and union membership was 64.6%. The mean time working at the port was 11.9 years (standard deviation ± 12.5). Occupational low back pain was reported by 17% of respondents, leading to an absenteeism rate of 19.7%. Physical activities helped improve the feeling of vitality for work performance.

CONCLUSIONS:

The prevalence of low back pain among respondents was 17%, not influencing their quality of life, with an absenteeism rate of 19.7%. Doing physical activities was common among respondents.

INTRODUCTION

Low back pain is the feeling of pain or discomfort in the lumbar region, which covers the area below the rib cage and above the pelvis.1 It can be divided by pain duration into acute (up to 3-4 weeks), subacute (3-4 to 12 weeks), and chronic (over 12 weeks).1 Another possible classification is primary, secondary, mechanical, axial, inflammatory, infectious, tumor-related, metabolic, traumatic, and others.1 Low back pain is the second most frequent symptom in medical consultations (first is headache),1^,2 accounting for numerous cases of hospitalization and surgical intervention.

Epidemiologically, 50 to 80%1 of the population has experienced or will experience, at some point in life, a low back pain episode, with recurrence in the first year in 50-60%3 of cases and possibly leading to disability in 30%.1^,2^,3^,4 Pain most commonly affects men aged 40 to 45 years and women aged 50 to 60 years.1^,3 The worldwide prevalence of chronic low back pain is 10%.11 Up to 85%3 of the times, the etiology of low back pain is not established, being reported as unknown.

Occupational low back pain is the major cause of absenteeism.1^,3^,4^,5 Because it affects the economically active population, it represents a socioeconomic and health problem. Some affected patients remain unfit for work for a long time or are given a disability leave, which leads to a great financial loss for companies and families, in addition to the discomfort caused by pain.6

The Port of Santos is the largest port in Latin America and in the southern hemisphere. It accounts for almost 60% of Brazilian gross domestic product (GDP) and 1/3 of Brazilian trade.6 Approximately 3.6 million containers/year travel through its 16 kilometers in length, 110 kilometers of railroads, and 66 berths, where approximately 33,000 employees work, including those of Companhia Docas do Estado de São Paulo (CODESP), currently named Santos Port Authority; the Workforce Management Agency (Órgão Gestor de Mão de Obra, OGMO); the pilotage service; the Port Captaincy; the National Health Surveillance Agency (Agência Nacional de Vigilância Sanitária, Anvisa); the Customs office; the Federal Police; as well as customs brokers, port terminal employees, railroad workers, and independent workers, among others.6

The workforce in the port sector is diversified. Even with technological advances, manual labor is still required. Longshoremen, crane and forklift operators, tallymen, and others are exposed to overload, which may cause low back pain.7 The degree of physical exertion and musculoskeletal overload required for each function varies, but workers submit themselves to overexertion to be considered efficient, which results in job stability or better opportunities. However, this compromises their physical and mental health.5^,8

People with chronic pain experience a decline in quality of life due to musculoskeletal problems or depression and behavioral changes.2^,4^,5^,9 The World Health Organization (WHO), in the International Classification of Impairments, Disabilities, and Handicaps, reports that low back pain arises from psychological, physiological, and anatomical factors, either combined or alone.2^,3 Occupational diseases are classified into (I) diseases necessarily caused by work activities (workplace accidents), (II) diseases that have work activities as a contributing factor, and (III) preexisting diseases aggravated by work activities. Port labor contributes mostly to classifications I and II.10

Occupational low back pain is one of the most prevalent work-related musculoskeletal disorders (WMSDs), affecting 23% of health care workers in Brazil.2^,3^,5^,11 It is one of the most common diseases in developed and developing countries.2^,3 Little is found in the literature on occupational low back pain in port settings and its impact on workers’ quality of life. However, many studies have explored the field of occupational nursing and addressed general and metabolic musculoskeletal disorders.5^,11

Barbosa et al.8 investigated how workers deal with the diagnosis of an occupational disease. They evaluated workers from a Labor Court in northeastern Brazil and found pain and limitations due to repetitive tasks, disorganized workplaces, unspecific room designs, and psychological tensions such as pressure and relationship problems. Also, the respondents always mentioned the activities they were unable to perform after the diagnosis of repetitive strain injury (RSI)/WRMSD, demonstrating the substantial interference of the disease in their quality of life.

Soares et al.12 described how unhealthy working in a port is and how workers perceive the risks to which they are exposed, demonstrating that knowledge of the risks is based on contact with other workers, consisting of an internal learning mechanism.12 Machin et al.,7 in turn, mentioned a historical study on the identity of the port worker, in which the values of courage, pride, and physical strength were identified. Although these attributes ensured more opportunities to earn money, working outdoors, wearing wet clothes, and experiencing overexertion led to complaints of chronic low back pain. The illness then led to a decline in quality of life and exclusion from work.7

A fundamental article for this research paper was that of Almeida et al.,5 in which 953 medical records of workers treated at the OGMO Occupational Medicine Outpatient Clinic in Rio Grande, state of Rio Grande do Sul, were reviewed, showing 527 diagnoses of musculoskeletal diseases, circulatory system diseases, respiratory system diseases, and psychological and behavioral disorders. The treated population was mostly male (90.4%), under 50 years of age (52%), and working for more than 19 years at the port (51.7%). Regarding musculoskeletal findings, low back pain and hypertension prevailed in the circulatory disease group; asthma and bronchitis in the respiratory disease group; and depression in the mental disorder group. Quality of life and behavior at work were significantly affected, which added a risk for workplace accidents. Even non-work-related diseases such as diabetes and hypertension were influenced by work overload because patients did not eat properly or were not interested in activities of daily living.5

Cezar-Vaz et al.11 investigated workload and associated factors that increase or decrease it for port workers. They interviewed 232 male workers. In conclusion, port labor was shown to have physical (heavy lifting, pulling, pushing, stacking), mental (scheduling, planning), temporal (fast or slow performance of tasks), performance (how much success can be achieved in a given function), and emotional (feelings of insecurity, depression, irritability caused by work) demands. Professional category and work shift were the factors that increased workload. Age was the factor that decreased it.11

In view of the above, we aimed to determine the prevalence of chronic low back pain among port workers and whether there is an influence on their quality of life, as well as to investigate physical activity level and absenteeism rate among these workers. To design the strategies required to address this situation, the first step is to quantify the problem. Then, correlations are established, and this creates a path for seeking solutions that reflect the well-being of the worker.

METHODS

A cross-sectional study based on prospective data collection was conducted. The research project was registered on Plataforma Brasil and approved by the Research Ethics Committee at Universidade Metropolitana de Santos (UNIMES) with protocol number 2568827. A convenience sample was recruited, and data were collected from June to November 2018 from Port of Santos workers who underwent periodic examinations at the Department of Occupational Medicine at Instituto de Análises Clínicas de Santos, on a first-come, first-served basis. The inclusion criterion was being employed in a port job for over 1 year. People who had already undergone spinal surgery, who did not sign the informed consent form (ICF), or who could not understand the questions were excluded. A structured questionnaire was used to identify the respondent.

The Roland Morris Disability Questionnaire (RMDQ)13 was used to obtain information about limitations or disabilities caused by back pain. Respondents should read the 24 statements and tick the ones that best represented their status referring to pain and functional limitation. The higher the score, the poorer the functional capacity. The 36-Item Short Form Health Survey (SF-36)14 assesses the respondents’ health perceptions and performance of their activities. The questions include the following items: physical functioning, physical health problems, general health perceptions, vitality, emotional health problems, social functioning, and bodily pain. Both instruments have been officially validated for use in Brazil.10^,15 The questionnaires were completed by Port of Santos workers after they read and signed the ICF. The data were analyzed with the aid of IBM-SPSS, using the nonparametric Kolmogorov-Smirnov and Mann-Whitney U tests and Pearson correlation.

RESULTS

Eighty-two people were interviewed; their mean age was 42.9 years, and most of them were self-reported brown men (Table 1). Of the total, 53.7% were married; 29.3% were single; 9.8% were divorced; and 6.1% were in other types of relationships. Most of them had completed high school (48.8%), and 17.1% had completed higher education. The most common occupations are shown in Figure 1.

Table 1.

Gender and ethnicity of port workers, Port of Santos, Santos, state of São Paulo, 2018 (n = 82)

	n	%
Sex
Male	80	97.6
Female	2	2.4
Ethnicity
Caucasian	28	34.1
Black	23	28.0
Brown	31	37.8
Yellow	0	0.0

Figure 1.

Dockworkers occupations.

A 44-hour workweek was the most frequent (31.3%). Over 85% of workers did not work overtime, and most of them were not paid on a production basis. Formal employment, according to Brazilian Labor Law (Consolidação das Leis do Trabalho, CLT), was 70.7%, and union membership was 64.6%. The mean time working at the port was 11.9 years (standard deviation [SD] ± 12.5).

Low back pain was reported by 17.1% of workers, radiating into legs and feet, intensified most commonly by physical exertion at work, poor posture, and repetitive movements. A decrease in overload improved symptoms in 45.1% of respondents, and the use of analgesics also had a positive influence. Regarding the occupations, longshoremen had more cases of low back pain (19%), followed by tallymen (9.1%), and no foreman complained of low back pain. Only 31.7% sought medical care, and less than 20% underwent some type of appropriate treatment. Total absenteeism rate was 19.7%, and absence from work was more frequent among those with low back pain (Table 2). Most of them returned to work in 6 months.

Table 2.

Absenteeism rate versus low back pain among port workers, Port of Santos, Santos, state of São Paulo, 2018 (n = 82)

	Absence n (%)	No absence n (%)	Total n (%)	p-value
Low back pain	7 (50.0)	7 (50.0)	14 (100.0)
No low back pain	9 (13.3)	59 (86.7)	68 (100.0)	0.005
Total	16 (19.7)	66 (80.3)	82 (100.0)

Hypertension and diabetes mellitus (DM) were the most reported metabolic diseases. According to the WHO,11 the prevalence of hypertension in adults over 35 years of age in the American continent ranges from 14 to 40%, while the prevalence of DM is over 8.5% in adults over 45 years of age. Hearing loss was frequent in 12.2% of respondents, and previous orthopedic changes such as fractures and degenerative joint disease were also reported. Other frequent comorbidities were hypertension (12.2%), DM (4.9%), and asthma (2.4%). Regular physical activity was reported by 65.9% of workers, and soccer was the preferred modality, played on average 3 times per week. Weight training and walking were also among the workers’ exercise preferences. Among those who did not report any physical activity, complaints of low back pain prevailed (Table 3).

Table 3.

Physical activity versus low back pain among workers at Port of Santos, Santos, state of São Paulo, 2018 (n = 82)

	Low back pain	No low back pain	Total	p-value
Active	7 (8.5)	47 (57.4)	54 (65.9)	0.21
Sedentary	7 (8.5)	21 (25.6)	28 (34.1)
Total	14 (17.1)	68 (82.9)	82 (100.0)

The mean RMDQ score was 2.1 (SD ± 3.5), with a significant difference between those with and without low back pain. Question 2 (I change position frequently to try and get my back comfortable) was ticked by 20 respondents. Questions 6, 11, and 21 were also frequently ticked. One worker aged 80 years, a tallyman working for 45 years in the port, responded positively to 20 questions (maximum score possible = 24) (Table 4). A score 4.0 (± 3.8) found in the group of workers with low back pain means greater limitation in activities of daily living due to pain.

Table 4.

Roland Morris Disability Questionnaire (RMDQ) administered to port workers, Port of Santos, Santos, state of São Paulo, 2018

RMDQ	Score	p-value
Maximum score possible	24.0
Mean for total sample	2.1 (±3.5)
Mean for low back pain group	4.0 (±3.8)
Mean for no low back pain group	1.6 (±3.3)	0.006*

^*Mann-Whitney U test.

The lowest SF-36 score referred to general health status, followed by vitality and pain. A comparative study between groups with and without low back pain was statistically significant for the domains of physical functioning and general health status. The results are shown in Table 5.

Table 5.

36-Item Short Form Health Survey administered to port workers with and without low back pain, Port of Santos, Santos, state of São Paulo, 2018

Domain	PF	RP	BP	GH	VT	SF	RE	MH
Mean for low back pain	78.2	80.3	71.1	50.1	68.9	80.3	76.1	80.5
SD	±21.3	±32.7	±24.0	±19.2	±21.9	±24.3	±42.2	±16.2
Mean for no low back pain	92.2	86.7	79.3	61.5	73.0	85.8	90.6	80.8
SD	±14.9	±28.8	±19.9	±13.0	±16.7	±18.5	±22.9	±14.1
p-value*	0.002			0.032

BP = bodily pain; GH = general health; MH = mental health; PF = physical functioning; RE = role-emotional; RP = role-physical; SD = standard deviation; SF = social functioning; VT = vitality.

^*Mann-Whitney U test.

DISCUSSION

Although low back pain is frequently reported by port workers, scientific publications in indexed journals were found to be scarce. Only one article5 with the same experimental design was retrieved from the searched databases. Lack of statistical data and limited support to research in Brazil prevent dedication to scientific production.

According to the WHO, acute low back pain will be experienced by up to 90% of people before 25 years of age.1^,2 Symptoms usually disappear without specific treatment. The risk of recurrence in 1 year is 60%. For chronic low back pain, the prevalence in the general population is 10%, affecting mainly those between 45 and 50 years of age.2

A study conducted in the United States found that 22.6% of construction workers had chronic low back pain. In Brazil, the numbers are similar, affecting 23% of workers in general.1^,2^,3 Similar prevalences among workers subject to similar physical exertion conditions were expected. Greater use of technology to replace manual labor has probably had a direct influence in low back pain decrease.18

The main factors associated with chronic low back pain described in the literature are heavy work, heavy lifting, working in a sitting position, lack of exercise, and psychological problems.2 This study focuses on a work activity that is, in summary, a set of the problems described. Port workers, especially longshoremen, are exposed to heavy lifting throughout their shift.17^,18 Heavy work, heavy lifting, and nonergonomic positions are common in this setting, and, despite being arduous and unhealthy, port labor attracts many people, especially because there are opportunities for unskilled employees, a common situation faced by Brazilians. Tasks related to heavy lifting and cargo handling on the deck and outside the ships are a great opportunity for physically strong workers.

Heavy lifting activities, regardless of where they are done (in the best gym in the city or in the workplace requiring most manual labor), accelerate the degeneration of musculoskeletal tissues. The spine in bipeds is already subject to a natural effort to remain in an upright position, therefore being more sensitive to the action of external forces.1

In this study, less than 2.5% of respondents were women. The main paper supporting this study found a female prevalence of 5.3%5 among employees; however, in a study of port workers in the state of Rio Grande do Sul,12 the sample consisted exclusively of men. The small sample size prevents assertions, but, in theory, jobs involving greater physical overload tend to attract less women. In Brazil, 44% of workers are women, consisting of the largest proportion in Latin America.16 However, the need for physical strength, among other factors, leads to a reduced number of women in the port sector. However, the greater the computerization and modernization of ports, the more this scenario changes. In this study, the female presence was small (2.4%).

All respondents in this study were literate, and most of them had completed high school. Longshoreman was the most reported occupation and had the highest number of complaints of low back pain. Loading and storing cargo inside the ships under adverse weather conditions, with the risk of falling or having serious injuries, is the longshoreman’s job. The prevalence of low back pain was 9.09% among tallymen, and no foreman complained of low back pain. This relationship between exposure to overload and complaints of low back pain becomes evident when the activity performed by the worker is evaluated.4^,5^,9^,11^,17^,18 Most respondents were formally hired (CLT workers) and were union members.

The low proportion of port workers with underlying diseases and acquired deficits reflects the younger age of workers and the use of protective equipment for preventing occupational accidents.17^,18 Tightening of labor safety laws has provided many benefits, and more intense enforcement and more severe punishment help to reduce the risk of greater physical harm. It is believed that there has been a greater awareness regarding occupational safety, leading to improved working conditions.18

There was no correlation between the most reported diseases and complaints of low back pain. Hypertension and DM are metabolic diseases, and although microvascular changes in DM may contribute to progressive joint degeneration, their presence does not cause occupational low back pain. The same logic can be applied to the complaint of hearing loss. Physical activity was reported by 65.9% of participants, and 80% of these did not complain of low back pain. A positive correlation between physical fitness and a better capacity to perform overload activities is expected.1^,4^,8

The RMDQ scores were low in general but statistically worse in workers with low back pain (p = 0.006). Low RMDQ scores are consistent with what has already been explained, i.e., that a younger population that proactively preserves health has fewer complaints of work-related disorders (or are less affected by them). The main complaint was “I change position frequently to try and get my back comfortable,” which denotes some discomfort. The assessment of groups with and without low back pain demonstrated a strong positive correlation between pain and decreased quality of life; however, it was statistically significant in only two domains.

Chronic pain leads to a feeling of physical frailty and to emotional changes that impair sleep, concentration, interpersonal relationships, and emotional status, leaving a clear impression of unstable health. There is no doubt that port workers have a poor overall quality of life.

The low back pain rate among respondents was lower than that among workers in general, and absenteeism rate was about 19.7%,2^,5^,17^,18 with most employees returning to work in 6 months. The percentage of absence from work among those with low back pain was statistically higher than that among those without low back pain,17^,18 as expected. It is worth noting that absenteeism has an economic impact.

As shown in this study, the quality of life of those working at Port of Santos is not negatively influenced by their work activity. There was no statistical relevance to support the opposite, but working in the port can still be unhealthy. New laws have greatly improved this activity, with significant adherence of workers with higher education.4^,7^,12^,17^,18 The assumption that this category works informally and is suffering and dissatisfied was not confirmed in the responses.

In conclusion, although a higher prevalence of low back pain in a setting where tasks with risk of overload are performed seems obvious, few studies describing the prevalence of low back pain in port workers were found. This paper contributes to the literature with the information that the pain rate among the respondents was not different from the general rates for workers exposed to physical exertion and that their quality of life has not undergone any statistically significant changes. Conducting comparisons between different jobs in several different ports is possible if there are studies confirming previously assumed knowledge.

As expected, physical activities had a positive influence on the reported quality of life, being directly related to improved physical vitality and better performance at work. Absenteeism rate was markedly higher among workers who complained of low back pain.