Gereç ve Yöntem: Hastanede çalışan doktorlar (n = 30), sağlık görevlileri (30) ve hasta bakıcılar (30) çalışmaya dahil edildi. Otonom sinir sistemi (OSS) aktivitesi, kalp atış hızı değişkenliği (KHD) ile belirlendi ve kişilerin stress algıları, Durum ve Süreklilik Kaygı Envanteri (STAI-II) ile değerlendirildi. KHD, hem gündüz hem de gece vardiyalarında gerçekleştirilen kısa süreli elektrokardiyogram kayıtlarından elde edildi ve NN aralıklarının standart sapması, SDNN (ms); düşük frekans, LF; toplam güç, TP (ms²) gibi parametreleri içerdi.

Bulgular: SDNN değeri, doktorlarda (42±3) hasta bakıcı grubuna göre (32±2) daha yüksek bulundu (p=0.014). LF, hasta bakıcı grubuna göre doktorlarda daha yüksekti [sırasıyla (805±102, 555±97 p=0.046]. TP, doktorlarda [1651 (1129-2903)], ofis görevlileri grubuna [1466 (764-2313)] ve hasta bakıcı grubuna [786 (508-1821)] göre farklı değildi (p=0.065). STAI-II hasta bakıcılarda [45 (42-48) puan] doktorlardan [40 (35-45) puan, p=0.002] daha yüksekti.

Sonuç: Aynı ortamda fakat farklı işlerde çalışmanın, kalp hızı değişkenliği üzerine farklı etkiler oluşturabileceği gözlenmiştir. Ayrıca, doktorlar, daha çok çalışmalarına rağmen, ede edilen bulgular, otonom sinir sistemi aktivitesinin ve stres algısının daha iyi olduğunu göstermektedir.

Social hierarchical factors such as low status and occupational factors pose a threat to cardiovascular diseases (CVD) ^8,9. In addition to social factors, low socioeconomic status increases the risk of disease in healthy people. Socioeconomic status influences the risk of multiple diseases, frailty, and disability. The reason for these seems to be more social inequality. Strong evidence suggests that social inequalities exist in multiple diseases, frailty and disability; all three conditions were associated with a greater risk of mortality ¹⁰. The relationship between socioeconomic status and cardiac outcomes can be related to education, income or profession ¹¹. Low socioeconomic status creates mental stress and increases the risk of cardiovascular disease ¹². In studies, it was emphasized that negative physical and psychosocial work environments, working conditions (such as shift work, overwork load) are related to CVD ¹³. Shift work is linked to a variety of health problems, including harmful effects on the cardiovascular system ¹⁴. Studies support that psychosocial stressor at work have negative effects on CVD, including high blood pressure, CVD incidence, and CVD recurrence ¹⁵. One of the systems activated in response to stress is the autonomic nervous system (ANS) ¹⁶. The autonomic nervous system activates the sympathetic nervous system while suppressing the parasympathetic nervous system (PSS) in excessive or prolonged stress ^17,18. Reduced parasympathetic modulation is associated with increased risk of cardiovascular diseases ¹⁹. Heart rate variability (HRV) is a noninvasive method used to evaluate ANS status and its regulation on the heart ²⁰. HRV can be used to evaluate autonomic imbalances, diseases and mortality ¹⁸. Work stress has been associated with reduced HRV ²¹. There are studies showing a positive relationship between low HRV and mortality ¹⁸.

Shift work has been associated with numerous negative effects on health and is one of the most important stress factors activating the autonomic nervous system.

The aim of this study was to determine the effects of occupational status (doctor, health officer, patient caregiver) on stress perception and autonomic nervous system activity in hospital staff. Additionally, as these parameters likely to be affected by menstrual cycle, we studied only on male personnel.

MINTAB statistical package (PA, USA) was used for power analysis. It was calculated that 16 individuals should be included in the paired t-test in order to obtain a difference of 1 standard deviation difference when standard deviation was 22.5 for SDNN and the alpha value was 0.05. The male volunteer participants were informed about the study and written consent was obtained from them. Doctors (n=30), health officers (30) and patient caregivers (30) working at the hospital were included in the study. The inclusion criteria were; being healthy, being in the 18-45 age range and and not using any medication. Doctors were working between 08:00 a.m. and 05:00 p.m. However, in case of night shifts, they continued to work for 32 hours continuously. Health officers and patient caregivers work with a similar variable shift system. Rotating-shift system consisted of daytime shifts between 08:00 a.m. and 04:00 p.m. and night shifts between 04:00 pm and 08:00 a.m. Rotating-shift system employees were given at least 16 hours to rest after the day and night shifts. The locations of the day and night shifts were constantly changing, with work schedules arranged at two-week intervals. Data on total working hours and monthly income of the participants are added to Table 1. Demographic characteristics of the study population are represented in Table 1. Body mass indexes [BMI; (weight in kilograms/height in meter2)] of the subjects are also calculated.

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Table 1: Demographics of the study population. Data presented as the interquartile range [median(Q1-Q3)]. p<0.05 was considered as level of significance.

The State-Trait Anxiety Inventory (STAI): The State-Trait Anxiety Inventory (STAI) was used in this study. STAI was developed in 1970 by Speilberger et al. ²² the adaptation of the scale to Turkish, validity and reliability studies were carried out by Öner and Le Compte ²³ in 1983. The STAI is a self-assessment questionnaire that is used to find out how participants felt at a particular time or under a specific condition. It has two subscales, the State Anxiety Scale (S-Anxiety) and the Trait Anxiety Scale (T-Anxiety). We used the Trait Anxiety Scale (T-Anxiety) in our study. The STAI helps professionals differentiate between feelings of anxiety and depression by making a clear distinction between the transient state of anxiety and the more general and prolonged persistent anxiety ²⁴.

Heart Rate Variability and Arterial Blood Pressure: All participants were asked not to consume stimulant beverages such as tea and coffee for approximately 2 hours before the heart rate variability (HRV) measurement. In order to determine HRV, electrocardiogram (ECG) recording in volunteer participants were taken for 5 minutes in supine positions with eyes open. ECG recordings were taken once between 4:00 pm and 10:00 pm. Poly-Spectrum 8-E (Neurosoft, Ivanovo, Russia) was used for ECG record and HRV analysis was made with the HRV software program of the same device (Neurosoft, Ivanovo, Russia). HRV is used in the non-invasive evaluation of the autonomic nervous system activity ²⁵. All inter-beat intervals were visually checked to ensure that the program recognized all of them accurately. Time domain parameters (HR, SDNN, RMSSD and pNN50) and frequency domain parameters (TP, LF, HF and LF/HF) were evaluated. Time domain parameters: Heart rate, HR (bpm); standard deviation of NN intervals, SDNN (ms); root mean square of successive RR interval differences, RMSSD (ms); percentage of successive RR intervals that differ by more than 50 ms, pNN50 (%) and total power, TP (ms²) ²⁶. High-frequency, HF (ms²) (synchronous with respiration, generally in the band 0.2–0.45 Hz); low-frequency, LF (ms²) (band 0.03–0.15 Hz); and ratio of LF-to-HF power, LF/HF (27). Arterial blood pressure was measured indirectly using an automated digital blood pressure monitor (Omron, M6 comfort, China).

Statistical Analyses: Statistical analyses were carried out using statistical software (Minitab 19 USA). Distribution of the data was checked by the Anderson-Darling test and non-normally distributed data was transformed into log 10 data for normal distribution. Following this transformation, normally distributed data were analyzed by One-way ANOVA test. Data with non-normal distribution despite the log 10 transformation were analyzed by the Kruskal-Wallis test. Diastolic and systolic blood pressure, heart rate (HR), SDNN and LF had normal distribution whereas the other data did not. Bonferroni correction Mann-Whitney test was used as post hoc analysis after Kruskal-Wallis. Tukey’s t test was used as post hoc analysis after one-way ANOVA. Data are presented as median (interquartile range as Q1-Q3) for non-normally distributed data whereas mean ± SEM was used for normally distributed data. p<0.05 was considered as level of significance.

Trait Anxiety Scale (T-Anxiety): STAI was higher in-patient caregivers [45 (42-48) points] than doctors [40(35-45) points, p=0.002].

Time Domain Parameters of HRV: HR (80±2, p=0.556) was not different in the doctors group compared to the health officers group (81±2, P=0.556) and the patient caregivers group (78±2 mm Hg). SDNN was higher in the doctors group compared to the patient caregivers group (42±3, 32±2 respectively, p=0.014) (Figure 1). Time domain parameters of the HRV are shown in Table 2.

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Figure 1: SDNN (a) and LF (b) values in men working in different professions in the health sector. The data are expressed as mean ± standard error for SDNN and LF. Different letters represent the differences between groups. p<0.05 was considered as level of significance.

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Table 2: Heart rate variability index results in men working in different professions in the health sector. Data presented as the interquartile range [median(Q1-Q3)] or mean±SEM. p<0.05 was considered as level of significance.

HRV Frequency Domain Parameters: TP [1651(1129-2903), p=0.065] was not different in the doctors group compared to the health officers group [1466 (764-2313)] and patient caregivers group [786 (508-1821)] (Figure 2). LF/HF [3.42 (1.42-6.52), p=0.293] was not different in the doctors group compared to the health officers group [3.53 (1.24-5.07)] and the patient caregivers group [2.46 (1.22-3.71)] (Figure 2). LF was higher in the doctors group compared to the patient caregivers group (805±102, 555±97 respectively, p=0.046) (Figure 1). HF [222 (120-459), p=0.065] was not different in the doctors group compared to the health officers group [217 (88-396)] and the patient caregivers group [160 (63-344)]. Frequency domain parameters of the HRV are shown in Table 2.

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Figure 2: TP (a) and LF/HF (b) values in men working in different professions in the health sector. Box-plot graph is shown for TP and LF/HF. There was no difference between the groups for TP and LF/HF. p<0.05 was considered as level of significance.

Systolic and diastolic pressures were not statistically significant between the doctor, health officer and patient caregiver groups. In addition, systolic and diastolic pressures were within normal limits in all groups. ANS affects blood pressure through adjustments in parasympathetic and sympathetic activity ³⁰. There is an increasing amount of studies that work stress may be associated with cardiovascular diseases ³¹. In addition, shift work is a risk factor for cardiovascular disease and hypertension ³². CVD is a leading cause of morbidity and mortality ¹⁸. It is known that socioeconomic status also has effects on CVD ³³. Poverty has always been associated with poor health, but this may not be the case in modern societies ³³. Although the specific contribution of genes and environment is not fully understood, environmental factors and lifestyle are thought to play a more dominant role in the development of CVD ³³.

HR was not statistically significant between the doctor, health officer and patient patient caregiver groups. In addition, HR was within normal limits in all groups. HR is under the influence of ANS ³⁴. HR assessment continues to be used as a health indicator from past to present ³⁴. Researchers emphasize that status and work stress are associated with illnesses and poor health ^18,31. Studies have shown that high resting heart rate is associated with increased mortality ³⁵. Researchers emphasized in their study that HR increased in acute stress situations, but HR decreased with chronic stress ³⁶. Therefore, there may not have been a difference between the groups because they have been doing this job for years in all three groups.

In our study, SDNN value was found to be lower in the patient caregiver group compared to the doctor group (Figure 1). SDNN is a measure for the evaluation of total sympathetic and parasympathetic activity ³⁷. A higher SDNN value is associated with a higher probability of survival ²⁶. Weakness of ANS can lead to a weakened ability to adapt to difficulties and a decrease in the ability to cope with emotional / physical stress factors ^5,38. Low HRV has been associated with conditions such as psychopathology, including anxiety ³⁹. The researchers emphasized in their studies that low SDNN values are associated with both morbidity and mortality ²⁶. HRV time-domain measurements decrease with age ²⁶. Hence, SDNN tends to decrease with advancing age ⁴⁰. Therefore, the decrease in SDNN value may also be due to the age difference. However, the fact that 20-29 and 30-39 age groups are consecutive in the age groups classification and there is no difference between the groups in ⁴¹ terms of other HRV parameters also suggests the possibility that age has less effect on SDNN. Work stress has been associated with reduced HRV ¹⁸. Among men, job stress has been associated with low HRV due to recurrent ANS activation ⁸. In our study, the STAI-2 score was found to be higher in the patient caregiver group compared to the doctor group. Researchers emphasize that status and work stress are associated with illnesses and poor health ^18,31. The researchers emphasized in the studies that low HRV is also associated with low socioeconomic status ⁴². Although social class has an effect on the cardiovascular system, its mechanism of action is not yet understood ⁴². Studies have shown that reduced education ^43, occupational status, and income ^43, are all associated with mortality, morbidity, and poor functional status ⁴². TP was not different in the doctors group compared to the health officer group and the patient caregiver group (Figure 1). TP is a marker of autonomic nervous system activity ⁴⁴. Higher TP is associated with better health ⁴⁵.

In our study, there was no difference between the groups in terms of PNN50, RMSSD and HF values. Some of the parasympathetic components of HRV are PNN50, RMSSD and HF ³⁸. Modulation of vagal tone is important for maintaining cardiovascular health ²⁶. Although there are some differences between studies, the consensus is that lower values of vagal function indices are prospectively associated with death and disability (18). High vagal activity is considered cardioprotective and hence associated with better health ⁴⁶. In our study, there were no difference between the groups in terms of VLF and LF/HF (Figure 1). Normal VLF value correlates with healthy state ²⁶. LF/HF is an indicator of sympathovagal balance ²⁶. An increase in LF/HF ratio indicates predominant sympathetic activity, while a decrease in LF/HF indicates parasympathetic dominance ⁴⁷.

LF has long been considered a measure of sympathetic activity ⁴⁷. The origin of LF power, however, has consistent controversy ⁴⁷. Thomas et al. emphasized in their study that LF and VLF do not represent cardiac sympathetic modulation of the heart and these parameters may reflect vagal mediated baroreflex cardiac effects ⁴⁷. In our study, the STAI-II score was found to be higher in the patient caregiver group compared to the doctors group. However, the LF value was found to be higher in the doctors group compared to the patient caregiver group. This situation seems to support the predictions of Thomas et al. However, the perception of physiological and psychological stress may be different ⁴⁸. Although they are STAI and HRV stress parameters, it has been observed that they may give different results in some studies ⁴⁹.

In our study, the STAI-II score was found to be higher in the patient caregiver group compared to the doctors group. STAI scores are commonly classified as no or low anxiety ^20-37, moderate anxiety ^38-44, and high anxiety (45-80) ⁵⁰. While moderate anxiety was observed in the doctors group, there was a high level of anxiety in the patient caregiver group. Among men, work stress has been associated with low HRV due to recurrent ANS activation ⁸. Stress in the workplace is an important public health risk associated with cardiovascular morbidity ¹⁸. CVD is the leading cause of death and disability worldwide ¹⁸. Researchers emphasize that status and work stress are associated with illnesses and poor health ^18,31. Low socio-economic status (SES) is associated with steadily increasing rates of morbidity and mortality when measured by income, education, or other indicators ⁵¹.

As a result, shift work is an important component of the modern world, but has been linked to risk for diseases such as cardiovascular diseases ⁵. In addition, researchers highlight that job status and stress are also associated with illnesses and poor health ^18,30. In our study, SDNN value was found to be higher in the doctor group compared to the patient caregivers group. In addition, the STAI-II score was higher in the patient caregivers group than in the doctor group. These collectively show that, even the doctors work hard and have higher responsibilities; they appear to have better heart rate variability parameters and less stress perception. As a result, the data suggest that job status may have significant effects on health, even in individuals working in the same environment.

Conflict of Interest: The authors declare that they have no conflict of interest.

Funding: There are no financial supports.

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