Influence of Chronic Obstructive Pulmonary Disease on Work Ability

Abstract

Chronic obstructive pulmonary disease (COPD) is a leading cause of mortality, morbidity and disability worldwide. COPD cannot always be defined as an occupational disease, because it is more of a work-related disease or a disease that worsens at work, and the patient’s ability to work will depend on the degree and duration of lung function damage. Very clearly and unambiguously, apart from smoking as a risk factor for the development of COPD, the workplace and work environment are also important. In our research, the largest number of patients with COPD worked at workplaces with special working conditions and were exposed to chemical, physical, and biological hazards at the workplace, which brings with it an increased number of sick days due to frequent exacerbations of the disease and reduced work ability.

1. Introduction

Cigarette smoking is the best-known and most common cause of chronic obstructive pulmonary disease (COPD) in the world [1]. Cigarette smoke causes airway inflammation in COPD, which is known to persist even after smoking cessation [2]. Other causes are more common in developing countries, namely passive smoking, environmental and workplace exposure, and lack of alpha-1-antitrypsin.

Indoor and outdoor air pollution is an important cause of the onset and development of COPD [3]. Certain professions where patients are exposed to harmful particles and gases at the workplace also represent risk factors for the onset of disease [4].

Given that chronic obstructive pulmonary disease is a multicomponent disease that, due to symptoms, therapy, and changes in functionality, leads to altered work ability and more frequent sick days, with our study we wanted to draw attention to how important the workplace of workers, especially in industry, contributes to the initiation of the disease and exposure to risks that may further exacerbate it.

COPD cannot always be defined as an occupational disease, as it is more of a work-related disease or a disease aggravated by work along with smoking. Many epidemiological studies have confirmed that long-term occupational exposure to various dusts increases the risk of developing COPD [5].

For work processes in which there is exposure to gases, vapors, and dusts, as well as unfavorable microclimatic conditions, the risk of exposure as well as the length of exposure at the workplace must be assessed. When it comes to dusts, the most common occupations for an increased risk of COPD are in the production of ceramics, barite cement, lignite, and brown coal mines. These are dusts with a possible fibrogenic effect, and relatively inert dusts. In technical and technological processes in production, there are numerous toxic substances that serve as raw materials. The synergy of several raw materials in the process of obtaining a finished final product is worse than a finished chemical compound. Inhalation of such compounds acts as one of the factors for exacerbation of COPD or, during prolonged exposure, for the development of the disease [6].

The evaluation of working capacity will depend on the degree and durability of lung function damage, so we evaluate it in the following way:

• Slight impairment of lung function (FEV1 > 80%), does not reduce the ability to work for the largest number of occupations.

• Moderate impairment of lung function (30% > FEV1 < 80%) leads to inability to work with moderate and severe physical exertion.

• Severe pulmonary function impairment (FEV1 < 30%) prevents any physical effort.

The measurement of the partial pressures of oxygen and carbon dioxide is also of great importance for the assessment of work capacity [7].

The ventilation of the space where the worker resides is important because synergistic action is also possible in the atmosphere of the present pollution.

Every worker suffering from COPD requires a change of workplace when the presence of respiratory irritants is found at the workplace, even when they do not exceed the maximum permissible concentration (MDK) [8].

At least every 2 years, they must undergo health examinations, which must include a diagnostic minimum for exposure to gases, vapors and dusts. The life of patients with COPD can be stressful because it forces life changes, which are also reflected in work functioning [9].

COPD is significant not only due to its large spread, but also due to economic pressure on health insurance funds, where large funds are allocated for the treatment and rehabilitation of patients [10, 11]. According to data from the World Health Organization (WHO), COPD is the fourth leading cause of death, after cardiovascular, malignant and cerebrovascular diseases. Nowadays, there is a significant increase in costs for the treatment of chronic lung diseases in the total costs of health care. The more severe the chronic disease, according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) [12], the higher the direct and indirect costs of treatment [13]. Indirect costs include loss of working ability, absence from work – sick leave, patient care and others. Indirect costs can be classified into two types: morbidity costs (time lost from work due to illness) and mortality costs (time lost due to premature death) [14].

The costs of sick leave, loss of working ability of patients with respiratory diseases, are estimated to amount to 41.4 billion euros, and COPD is responsible for more than half of this amount, i.e. 25.1 billion euros [15]. Since human capital is often the most important national asset for developing countries, the indirect costs of COPD could be a serious threat to their economies. This group of patients should be the focus of attention of workers, employers, and doctors, as well as health and pension insurance agencies [16, 17].

Men tend to have exacerbations more often, but in recent years the difference has decreased due to the increase in the number of smokers among women . The study conducted by Ljubičić [18] included 61 subjects with COPD, of which 41 (67.2%) were male and 20 (32.8%) were female. Such results may arise because male respondents mostly work at workplaces with special working conditions and are exposed to harmful noxious agents from both the workplace and the environment.

According to data published so far, approximately 328 million people suffer from COPD worldwide, of which 168 million are men and 160 million are women [18]. COPD usually occurs after the age of 40 and is mostly related to long-term smoking, although exposure to harmful workplace and environmental factors cannot be ruled out.

The GOLD report [12] describes the ABCD test, which divides COPD patients into four groups, A, B, C, and D. Groups A and B are low risk and have zero to one exacerbations per year, not leading to hospital admission, where Group A has less symptoms and Group B has more symptoms. Groups C and D are high risk and have two or more exacerbations or one or more hospitalizations per year, with Group C having less symptoms and Group D having more symptoms.

2. Material and methods

During the examination in 2019 in the Pulmonology Cabinet of the Health Center, a prospective study was conducted using appropriate questionnaires with a smaller retrospective part using previous medical documentation (medical history and other medical documentation), which included 150 respondents (workers) with already established and verified diagnosis of COPD. In the examined group, subgroups were formed in relation to the habit of consuming cigarettes (smokers and non-smokers), as one of the most important risk factors for the development of COPD.

Criteria for inclusion in the study:

• Patients older than 40 years.

• Diagnosed with chronic obstructive pulmonary disease.

• Voluntary consent to participate in research.

Criteria for exclusion from the study:

• Patients under 40 years of age.

• Workers suffering from malignant diseases and pneumoconiosis.

• That they do not suffer from COPD.

• To have no other comorbidities.

• Without voluntary consent to participate in research.

Each worker was examined by an occupational medicine specialist who performed and interpreted additional tests.

1. A detailed anamnesis was taken for each subject with a special emphasis on the work anamnesis, absence from work and the habit of consuming cigarettes.

2. Each subject filled out a standardized questionnaire for COPD (CAT questionnaire).

   The COPD assessment test (CAT) questionnaire was created as a result of the need for doctors to better understand their patients’ condition in order to achieve the optimal treatment of COPD. The description of the disease, which was taken as the framework concept of the questionnaire, was created after numerous expert meetings with doctors and patients. Additionally, two validation studies as well as patient testing were performed as part of the European Quality of Life Survey. The entire research resulted in a short, simple, validated questionnaire consisting of eight simple questions that provide the best framework concept for the description of the disease. Each question quantifies the impact of the disease on the patient’s quality of life based on a semantic scale from zero to five. The values on this scale are circled by the patient for each of the eight questions. The values of the obtained results range from 0 to 40. While spirometry remains the gold standard for confirming the diagnosis and determining the severity and stage of COPD, but it does not fully reflect the impact of this disease on patients’ lives.

3. A physical examination was performed with special emphasis on auscultatory findings on the lungs.

4. Anthropometric measurements were taken, including body mass (BW), body height (BW).

   An anthropometer according to Martin was used to measure body height (BH) with a measurement accuracy of 0.1 cm. Each subject was measured without shoes, hands relaxed next to the body, heels together, with the head positioned so that the so-called the Frankfurt plane (an imaginary line connecting the tragus of the auricle and the outer corner of the eye) should be horizontal.

   A medical decimal scale with a movable weight was used to measure body mass. The measurement accuracy on the same is +/−0.3 kg.

   The spirometric examination was performed in the Pulmonology Office of the Sarajevo Hospital on the “Master Screen Body Jaeger” spirometer, which was manufactured in Germany.

5. Spirometry is the gold standard for diagnosing chronic obstructive pulmonary disease (COPD). It is a simple, quick and painless test that is performed to assess lung function by measuring the volume of air that the patient can exhale from the lungs after maximal exhalation. The patient was explained how to test the lung function and how he should cooperate with the nurse in order for the findings to be technically correct. The patient’s nose must be plugged with a clip. The patient will first breathe normally through the mouthpiece, which he has covered well with his lips.

   The patient then breathes with forced inhalation and exhalation. This respiration was repeated three times, and the best result will be taken for analysis.

   Lung volumes (respiratory volume, inspiratory reserve volume, expiratory reserve volume) and capacities (vital capacity, inspiratory capacity), as well as respiratory volumes as a function of time (forced expiratory volumes) are determined by spirometric testing. During the forced expiratory maneuver, vital capacity is obtained, which in this case is marked as forced vital capacity (FVC) and forced expiratory volume during the first second (FEV1) as well as flow rates in the flow/volume curve.

6. We monitored working capacity on the basis of absence from work and monitoring of spirometric findings.

3. Results

The study that we conducted confirmed that COPD significantly affects the working ability of the respondents, and therefore the quality of life in all its spheres. The study included 150 subjects suffering from COPD, 105 male subjects and 45 female subjects.

Our study, compared to others, included more male patients with irreversible airway obstruction. The average age of our subjects was 60.16 years (SD ± 5.12 years) (Table 1).

Minimum age	Maximum age	Average age of respondents	The age range is	Standard deviation SD
40 years	70 years	60.16 years	30 years	±5.12 years

Table 1.

Demographic characteristics of subjects with COPD (age).

Most of the respondents who had chronic obstructive pulmonary disease were from the 60 to 70 age group (55.00%). This was expected because COPD takes decades to fully develop. The group up to 70 years of age was taken into the research because employees in certain workplaces had the possibility to work up to 70 years of age. In the research of Skrbić, the average age of the subjects was 64.85 years ±10.1, which is a similar value as in our research [19]. Therefore, the higher the age, the greater the number of people with COPD, which brings with it an increased number of sick days due to frequent exacerbations of the disease and reduced work capacity.

The analysis of the COPD stage of the subjects of this study, according to the GOLD ABCD tool, yielded the results reported in Table 2. Most respondents were in the group with moderately severe and severe stage of the disease. In these patients, due to their age, especially if they have not stopped smoking, the disease is expected to worsen, with occasional hospitalizations, due to progressing symptoms. COPD worsens progressively, and it is often difficult to find the cause of the exacerbation of the disease and the transition to a more severe stage. The results of our study agree with results of the study of Maričić. and most respondents were in the group with stages B and C [20]. According to data from the Institute of Public Health of the Federation of Bosnia and Herzegovina, it is believed that one in 10 inhabitants of Europe has a mild or severe form of COPD, and that the large number of smokers among the inhabitants of the Federation of Bosnia and Herzegovina (44.1%), as well as increasing air pollution affects are major contributors to the causes of death [21].

COPD stage	Number of patients	Percentage in relation to the total number of patients
A	33	22.00%
B	40	26.67%
C	44	29.33%
D	33	22.00%
Total	150	100.00%

Table 2.

Number of subjects per COPD stage.

The duration of COPD for patients in this study is shown in Figure 1. The average length of the disease is 25.9 years ±11.9. Analysis of the available literature yielded similar data, where the duration of COPD in subjects from group A was 15.6 years, and in subjects from group B 25.5 years [22].

Figure 1.

Duration of COPD in patients (in years).

The above statistics show that the development of COPD is generally preceded by a long history of smoking. Typically, nicotine weakens the line of defense in the lungs, the defense systems are activated, mucus secretion increases, and obstruction develops that is initially reversible but eventually becomes irreversible. In addition, airway distortion occurs due to loss of alveolar support and destruction of alveolar septa. For all this, it takes many years for the disease to develop to its full extent, and one of the reasons for development may be insufficient prevention at the primary level of health care.

Quitting smoking can bring many benefits for people with lung diseases. They will be less prone to lung infections and exacerbations of the current condition, they will have fewer hospitalizations, their oxygen levels will be higher and their carbon monoxide levels will return to normal. As many of the symptoms will be alleviated, they will be less likely to be temporarily unable to work [23]. However, according to the results in Table 3, the ratio of the number of smokers to ex-smokers among the respondents is about 2.6 and, unfortunately, the number of respondents with smoking habits is 108, i.e. 72.00%, with only 42, i.e. 28.00%, ex-smokers.

	Number	Percentage
Smokers	108	72.00%
Ex- smokers	42	28.00%
Total	150	100.00%

Table 3.

Ratio of the number of smokers and ex-smokers among the respondents.

Results in the available literature are similar to ours [24]. It is very difficult to convince smokers that smoking promotes further reduction of lung function and prevents adequate treatment of any deterioration. Smoking is part of the daily routine for these patients and causes a strong addiction, so smokers are unmotivated to stop smoking. Studies have shown that in COPD and other lung diseases, the most important thing is to stop smoking, not to reduce the number of cigarettes [23].

For people with COPD, neither too little nor too much body mass is desirable because both can lead to worsening of the disease and earlier loss of working ability. Malnutrition is common in COPD patients. Loss of muscle mass and strength of respiratory and skeletal muscles is characteristic of patients with COPD and is an independent predictor that increases the frequency and severity of exacerbations [25].

On the other hand, the loss of muscle mass is often not measurable from the patient’s overall weight because it is masked by the accumulation of fat, which can worsen the condition and prognosis.

Table 4 shows that the height distributions of the subjects and the average weight of all patients in each height group. The average height of the male subjects was 176.48 ± 6.90 cm, and that of the female subjects was 163.80 cm ± 9.23 cm. The average weight of the male subjects was 86.52 kg ± 14.98 kg, and the female 73.33 kg ± 11.82 kg. The smallest body mass measured in men was 48 kg, and in women 49 kg. These results did not differ significantly from those of Šrbič, where the smallest weight was 42 kg in the group with COPD, and the average weight was 74.34 ± 17.70, without gender division [19].

Male/female	Height (cm)	Number of respondents	Avarage weight (kg)
Male	140–150	2	49.50
Male	151–160	13	69.31
Male	161–170	23	73.83
Male	171–180	53	84.94
Male	181–190	14	102.79
Total male		105	82.28
Female	140–150	1	48.00
Female	151–160	3	68.33
Female	161–170	8	68.38
Female	171–180	25	86.64
Female	181–190	8	97.38
Total female		45	83.22

Table 4.

Heights and avarage weight of respondents by gender.

The results of many studies indicate that, in addition to smoking, one of the risk factors for a higher incidence of COPD is exposure to industrial dust and chemicals that are present in workplaces and the working environment. In most cases, these are jobs with special working conditions. In the group of 150 respondents, the type of occupation was: tinsmith, car tinsmith, varnisher, policeman, armorer, pump salesman, manual worker, cook, farmer, bricklayer, storekeeper, hairdresser, cleaner, metal turner, fitter, shoemaker, postman, operator, pedagogue, programmer, social worker, physiotherapist, market seller, security guard, sanitation technician, driver, speech therapist, cashier, architect, and construction worker. These occupations involve workplaces with special working conditions where the respondents are exposed to a wide range of harmful noxious agents. A small number of subjects did not fall into this category, and these are for the most part respondents with a higher professional education who are not exposed to the harmful effects of the group of workers with special working conditions (Table 5).

Substances	Occupations
Paints	Car varnisher; bricklayer
Dust	Armorer; cleaning lady; NK construction worker; tinsmith; metal turner; baker; assistant cook; carpenter; farmer; storekeeper
Motor oil	Auto tinsmith
Exhaust gases	Auto tinsmith; policeman
Varnishes	Car varnisher; carpenter; bricklayer
Gasoline	Auto tinsmith; farmer; shoemaker
Chemical substances	Cleaning lady; hairdresser; sanitation technician
Weather conditions	Cleaning lady; policeman
Shift work	Civil servants; policeman; nurse
Work at heights	Electrical fitter; construction worker
Lifting loads over 25 kg	Manual worker
Micro climate conditions	Tinsmith; manual worker; fitter; metal turner; market seller; farmer
Glue	Shoemaker
Heat	Baker
Additives	Baker
Evaporation	Sanitation technician
Pesticides	Farmer
Fertilizer	Farmer
Temperature change	Baker; merchant

Table 5.

Workplace conditions in relation to harmful substances and microclimate.

Assessment of working ability through the occupational requirements survey (ORS) is an assessment of the compliance of the health condition of the worker, his physical and mental abilities, with the requirements of jobs and work tasks, as well as with the conditions of work and the working environment. Since the physiological and psychophysiological capabilities of the worker and the physiological demands of the workplace are constantly changing, the assessment of working ability is not a static activity but a continuous process that follows the worker and the working conditions at his workplace during his entire working life, starting from the first choice of title, the preliminary examination upon starting work, and regular periodic examinations, all the way to the evaluation of the remaining work capacity. Working ability as a specific activity of occupational medicine is primarily a preventive medical activity with the aim of preserving health and working ability, i.e. preventing the occurrence of disability, reducing the number of occupational diseases and injuries at work, and increasing safety and productivity at work [26].

Certain jobs are associated with greater risk due to the exposure of workers to various chemical, physical, and biological hazards. If a worker with COPD works in jobs where harmful emissions into the working environment occur during the work process, then that worker is at risk of health detriments.

Table 6 shows the number of subjects in our study in each COPD category whose ability to work was or was not compromised by the disease. A total of 73 workers, or 48.67%, had preserved work capacity, and 77 workers, or 51.33%, had reduced work capacity. Preserved working ability is the highest in groups A and B, and decreased in groups C and D. This study was done to compare the working ability of subjects suffering from COPD divided into groups according to the GOLD classification, because no more recent data could be found in the available literature, except for the study of Okiljević et al., which indicate that the evaluation of work ability of respondents with COPD limits work ability [27].

Disease severity	Ability to work preserved	%	Reduced working capacity	%
A	33	22.00%	0	0.00%
B	38	25.33%	2	1.33%
C	2	1.33%	42	28.00%
D	0	0.00%	33	22.00%
Total	73	48.67%	77	51.33%

Table 6.

Change in work ability in patients with COPD.

Given that COPD shows a significant increase in morbidity and mortality and that in the next 20 years a further increase in incidence is predicted, the aforementioned will bring about changes in working ability and longer absences from work of patients [28]. Kuhajd’s doctoral dissertation “Risk factors affecting the outcome of respiratory rehabilitation in patients with COPD” indicated that in subjects with a disease duration of less than 10 years, rehabilitation results are excellent and amount to 77.3%. The success of the rehabilitation was tested over FEV 1, 6 minute walk test, “CAT” questionnaire and “mMRC” questionnaire [29]. That result is why it is necessary at the level of primary health care to apply prevention measures in a timely manner and determine guidelines in the fight against smoking, as well as risk assessment in workplaces.

Spirometric testing should be done in all people who are long-term smokers and who complain of cough and expectoration because early detection of the disease and the start of treatment improve the quality of life, prevent a decline in lung function and delay the onset of comorbidities [30].

Table 7 compares the stage of COPD to spirometry (which is the gold standard for diagnosing COPD) results from this study’s subjects. The lowest values of FVC and FEV1 were obtained by subjects from stage D according to GOLD, and the mean value of FVC was 44.50% (1.95 L). The mean value of FEV1 was 38.82% (1.35 L). These values are similar to results from other studies. Škrbić reported an FEV1 for COPD patients of 1.43 L [19], while Fernández-Villar reported an average value of 40.30% [31].

Disease severity	Number of patients	Percentage of Number of patients	FVC mean value %	FVC mean value L	FEV1 mean value %	FEV1 mean value L
A	33	22.00%	75.06%	2.98	61.32%	1.99
B	40	26.67%	70.08%	2.68	55.41%	1.74
C	44	29.33%	53.55%	2.00	47.49%	1.48
D	33	22.00%	44.50%	1.95	38.82%	1.35
Total	150	100.00%

Table 7.

Comparison of COPD stages in relation to spirometry.

Figure 2 showed the analysis of the working ability of COPD patients in relation to gender for our study. The percentage of respondents with reduced work ability was higher in male respondents and amounted to 41.33%, and in women it was 10.00%.

Figure 2.

Changes in working ability of respondents with COPD in relation to gender.

The results fit with the analysis of workplaces where more “male” occupations exposed the respondents to the harmful effects of the workplace.

Figure 3 shows the number of respondents who had reduced and preserved working ability in three age groups, 40–50, 51–60, and 61–70 years old. The age group with the highest percentage of reduced ability (35.33%) was 61–70 years (53 respondents).

Figure 3.

Change in work ability of respondents with COPD in relation to age.

The average duration of COPD was 31.83 ± 8.79 years for respondents with reduced working capacity and 19.75 ± 10.35 years for respondents with preserved working capacity. A histogram of the number of patients in the preserved and reduced categories in each duration range is shown in Figure 4.

Figure 4.

Change in working capacity in relation to duration of COPD.

Figure 5 shows the number of respondents with reduced and preserved working capacity in each of the four ABCD test categories, None of the respondents in Group A had reduced work capacity. Only 5% of those in Group B had reduced work capacity. The vast majority of those in Group C had reduced capacity, and all respondents in Group D had reduced capacity. Overall, work ability was reduced in 77 subjects, i.e. 51.33%, and preserved in 73 subjects. We could not obtain data from other studies on work ability in relation to the duration of COPD and its severity. Groups A and B include subjects who rarely have exacerbations of the disease and who respond best to rehabilitation measures. In stage A, doctors at the primary level of health care play an important role in preventing and preventing exacerbations of the disease and thus reducing the number of lost working days because early detection and recognition of risk factors can be of great importance in preventing the onset of COPD and in preventing the reduction of working capacity.

Figure 5.

Altered working capacity in relation to the severity of the disease.

Figure 6 shows the distribution of COPD symptoms among respondents. Cough occurs in the largest number of respondents n = 137. The next most frequent symptom was fatigue (n = 59), followed by dyspnea (n = 42), expectoration (n = 37) and chest pressure (n = 34). Other symptoms occur in a smaller number of respondents and include difficulty breathing, loss of breath, sweating, insomnia and suffocation.

Figure 6.

Distribution of COPD symptoms by frequency.

Of our examinees, 75 had reduced working capacity, and the leading symptom was cough. The same symptom occurred in 52 respondents with preserved work ability. All the leading symptoms occurred in the largest number of respondents with reduced working capacity. As already stated, the largest number of respondents worked in environments with special working conditions and were exposed to workplace hazards that caused increased bronchial secretion and, as a result, prolonged coughing. Symptoms of COPD vary and depend on the stage of the disease. Coughing clears the airways of mucus. Chronic cough is usually the first sign of illness. At first it occurs in the morning occasionally, and later on daily. The cough is generally mild at first and is often mistaken for a “normal” smoker’s cough, even though it is not a normal cough. In case of infection, cough is indicated and accompanied by expectoration of yellow or green secretion [31, 32]. Dyspnea is difficulty breathing or shortness of breath. As with cough, dyspnea is accompanied by a limited ability to move due to fatigue, and therefore a limited ability to work during that period. In advanced stages of the disease, dyspnea occurs even at rest. Chest pressure is tightness and a feeling of being unable to breathe.

Table 8 lists the more frequent exacerbations that are associated with absenteeism from work and temporary work incapacity.

Cough	Fatigue	Expectoration	Dyspnea	Difficulty breathing	Chest pressure	Insomnia	Lose breath	Choking	Weating	Working ability
52	12	8	0	3	20	0	14	0	1	% Preserved
34.67	8.00	5.33	0.00	2.00	13.33	0.00	9.33	0.00	0.67	% Preserved
75	45	30	39	20	14	4	4	1	2	% Reduced
50.00	30.00	20.00	26.00	13.33	9.33%	2.67	2.67	0.67	1.33	% Reduced

Table 8.

Change in working ability in relation to the difficulties of the respondents.

Figure 7 showed preserved working capacity within each workplace environment. All such environments were clerical workplaces, where there are no harmful noxious agents and which are not workplaces with increased risk.

Figure 7.

Ability to work preserved.

Figure 8 shows the number of respondents with reduced working ability in the various workplaces. Reduced capacity respondents were mostly exposed to harmful noxious agents at the workplace.

Figure 8.

Working capacity reduce.

Figure 9 shows preserved and reduced capacity for smokers and ex-smokers. In the smoker category the numbers of respondents with preserved and reduced working capacity were both 54. In the group of ex-smokers, working ability was reduced in 23 subjects, and preserved in 19.

Figure 9.

Working capacity in relation to nicotine abuse.

Absence from work due to illness or injury is considered temporary incapacity for work, during which the employee is entitled to salary compensation. Due to exacerbation of the disease (worsening), 131 respondents were on sick leave for up to 42 days during 1 year, and 73 respondents were absent from work due to illness for more than 42 days. The largest number of absences from work is concentrated in groups C and D, because their exacerbations are more severe and more frequent. This concentration is an indication that COPD significantly affects work ability. Which was the aim of our study. We wanted to draw attention to how important the workplace and work environment are for people diagnosed with COPD. Due to the accompanying manifestations of the disease, people with COPD cannot do heavy physical work, cannot work with chemical irritants, under masks, in a smoky area due to reduced lung volume, cough, ease of fatigue and loss of strength.

People suffering from COPD represent a burden for the Health Insurance Funds due to frequent exacerbations of the disease when therapy and in some cases hospital treatment is required. According to data from the White Book of the European Respiratory Association (ERS White Book) for the year 2011, obstructive diseases (COPD and asthma) had the largest share in total, direct, and indirect costs for respiratory diseases [17]. Total direct costs for respiratory diseases in 2011 amounted to 55 billion euros. Of that amount, COPD is responsible for 23.3 billion euros. In relation to indirect costs amounting to 41.4 billion euros, COPD is responsible for more than half of this amount, i.e. 25.1 billion euros. The cost of treating people with COPD in the United States was $38.6 billion for the same period [33, 34].

COPD represents a major public health problem in the world, and in our country as well, given that it has a high prevalence (up to 600 million patients worldwide), high morbidity (a frequent cause of hospitalization, which accounts for over 75% of the total costs for COPD), high mortality (the fourth leading cause of death), and huge treatment costs (they amount to 2–5 times more than the costs of asthma treatment). Nowadays, there is a significant increase in costs for the treatment of chronic lung diseases in the total costs of health care. The more severe the chronic disease according to GOLD, the higher the direct and indirect costs of treatment. Indirect costs include loss of ability to work, absence from work, and sick leave, i.e., the period of time for which the employee has the right not to work and to be paid compensation for that time due to inability to work.

Since human capital is often the most important national asset for developing countries, the indirect costs of COPD could be a serious threat to their economies. This group of patients should be the focus of attention of workers, employers and doctors, as well as health and pension insurance funds. In more severe cases, the costs of prevention are many times lower than the costs of treatment, and as such the WHO recommends them for implementation because, from a social perspective, prevention and interventions focused on disease control and slowing the progression of the disease and strengthening work capacity would save costs in COPD, including financial expenses in the category of direct costs-hospitalization and indirect costs.

COPD is also preventable through mitigation of influencing risk factors. In this sense, many strategies are implemented today, such as campaigns against smoking and exposure to tobacco smoke, reduction of air pollution and exposure to harmful substances in the workplace [35].

It is necessary to combine preventive and curative medicine, which reduces the possibility of aggravation and provides an even better overview of the health status of workers, when assessing the work capacity of patients with COPD [12, 36]. Also, ORS should have its role at all levels of prevention (primary, secondary and tertiary) of work-related health disorders [37].

4. Conclusions

This study examined the influence of the work environment and work ability in people diagnosed with chronic obstructive pulmonary disease. The largest number of respondents worked at places with difficult working conditions and were exposed to workplace hazards that caused increased bronchial secretion and, as a result, prolonged coughing. These environments are associated with more frequent exacerbations that are associated with being absent from work - temporary work incapacity and overall loss of workforce capability. The more severe the chronic disease according to GOLD, the higher the direct and indirect costs of treatment.

It is necessary to raise awareness about the primary prevention of all risk factors that lead to exacerbation of COPD because the costs of prevention are many times lower than the costs of treatment in more severe cases and as such WHO recommends them for implementation [14, 15, 17].

Conflict of interest

The authors declare no conflict of interest.