Sense of Coherence in Nurses: A Systematic Review

Background: Nurses experience high levels of distress due to the nature of their work and workplaces; Antonovsky’s salutogenic theory shows that individual and work-related factors can influence human health. The aim of this paper is to analyze the possible correlations with different work-related and individual variables, which influence or are influenced by Sense of Coherence (SOC) and verify the possible use of SOC scales to prevent negative health determinants in workplaces. Methods: Electronic databases were searched with selected studies compared for sample, sample size, study design and basic results. Cross-sectional studies were reviewed for correlations between individual physical and mental health, distress, burnout, job satisfaction and SOC, with intervention studies used to assess the possible impact of training on nurses’ SOC. Results: The review found several correlations between SOC and different work-related variables; but also with several individual characteristics. Conclusion: The review found that SOC was predictor of depressive state, burnout, job dissatisfaction among female nurses; therefore, SOC could be a health promoting resource.


Introduction
Nurses are in the front line in the psychologically demanding everyday-care of patients, which can often undermine their emotional balance, influencing both their physical and mental wellbeing [1]. Moreover formal caregivers are frequently burdened with an excessive workload, high working pressure and demands, spending more time at work than on other dimensions of their lives [2,3]. All together these factors may contribute to the creation of a stressful working environment, which requires great coping abilities.
According to the salutogenic theory [4], one of the most critical determinants of the capacity to cope successfully with distress is the Sense of Coherence (SOC), which shapes the individual experience of a stressful event and allows it to be perceived as meaningful, manageable and comprehensible. This can be achieved by mobilizing efficiently the so-called GRRs (generalized resistance resources), which include biological, material and psychosocial factors, triggering a virtuous cycle and in turn strengthening the personal SOC [5]. Similarly, the Conservation of Resources theory (COR) states that the stress can result from circumstances involving loss of valued resources, and that the desire to preserve the individual resources is the basis of the coping ability [6].
Transposing Antonovsky's theory on the working context, the SOC can be modified, in a positive or negative way, by the nature of the current working environment. This re-adaptation explains how "job resources" are an integral part of the GRRs and participate in the modeling of the worker's SOC, which consequently influences how the so-called job demands (hours and pattern of work, workload, Data extraction from the included studies were performed and, according to the variables assessed, they were allocated to the three categories mentioned above: "Work-Related Variables", "Individual Variables", "Interventions" (Figure 2). Features of the same article, falling into more than one category were assessed separately. Table 1 summarizes the articles.  Data extraction from the included studies were performed and, according to the variables assessed, they were allocated to the three categories mentioned above: "Work-Related Variables", "Individual Variables", "Interventions" (Figure 2). Features of the same article, falling into more than one category were assessed separately. Table 1 summarizes the articles. Data extraction from the included studies were performed and, according to the variables assessed, they were allocated to the three categories mentioned above: "Work-Related Variables", "Individual Variables", "Interventions" (Figure 2). Features of the same article, falling into more than one category were assessed separately. Table 1 summarizes the articles.    Age negatively correlates with depressive state (r = −0.18, p = 0.00) and positively to SOC (r = 0.27, p = 0.00) Inverse correlation between SOC and shift work (r = −0.16, p = 0.00), job rank (r = −0.14, p = 0.01), and overtime hours (r = −0. 33 Patients' age and type of illness seems to influence nurses' assessments of pain and distress Nurses with high emotional stability and high SOC scores assess pain and distress for acute patients as less intense and assess it more intense for chronic patients   (45.15), followed by the Comprehensibility and Meaningfulness subscales. They showed an inverse correlation between SOC and the dimensions of mental load investigated by the Meister questionnaire, such as Monotony, Unspecific Load and Mental Load [6]. The relationship between SOC and general working experience, position at work and employment characteristics was unclear, while some authors found no correlation [7,8], an inverse correlation between SOC and work experience was found by Debska et al. [6], in contrast Miyata et al. [9] observed a positive correlation. Among nurses there is a wide variety of work schedule such as regular, irregular, flexible, etc. Fusz et al. showed that day-shift workers had higher SOC score than shift workers, and that lower SOC value was found among irregular workers (58. 19), compared to flexible work schedule workers [10], while Kikuchi et al. observed an inverse correlation between SOC and shift work, job rank, and overtime hours [11]. Several studies found differences of SOC between different professionals, because there was higher SOC in nurses employed as strategic managers [7], Lindmark et al. likewise showed that clinical coordinators have higher SOC score, compared with all other professions, for example dental hygienists have higher scores for meaningfulness, and dentists have higher scores for manageability, compared with dental nurses [12].
Ando et al. described the relationship between the moral distress for nurses and several job characteristics, such as job satisfaction, SOC and mental health, finding an inverse correlation between Moral Distress Scale for Psychiatric Nurses (MDS-P) and SOC. Inverse correlations were found between subscales of the MDS-P and those of SOC [13]. Positive correlation was observed between SOC and workplace adaptability [14], and job satisfaction [11,14,15]. Moreover, Ida et al. identified SOC as an important factor affecting sickness-absence [14].
Lastly planning effective pain and distress management is a crucial part of the nurses' profession. Hall-lard et al. found that patient's age and type of illness seems to influence nurses' assessments of pain and distress, nurses with high emotional stability and high SOC scores assess pain and distress for acute patients as less intense and assess it more intense for chronic patients [16].

Work-Life Balance
Some authors, investigating Work-Life Balance as the proportions of percentages of time spent at work and private life (50/50 and below, 60/40, 70/30, 80/20 and above), reported significantly higher SOC scores in "50/50 and below" and "60/40" groups, whereas the lowest SOC scores were associated with the "80/20 and above" group [2,17].
As far as the Quality of Life (QoL) is concerned, the "50/50 and below" reported the higher scores for overall QoL and physical health, while the "80/20 and above" group the lowest in the overall QoL, in the physical health domain and in the environment domain. No significant differences among the four groups were observed in terms of social support, job satisfaction, and the psychological and social relationship domains of the QoL [2].

Work Related Trauma
Michael et al. investigated the effect of social and personal resources at work, related to trauma. They observed that nurses who did not report a traumatic event had the strongest SOC. This could be due to some causes, nurses with strong SOC did not perceive an event as traumatic, or in contrast, traumatic events influence the SOC [18].

Social Support
Social support and SOC were found to be significant predictors (p < 0.05) for all QoL domains. Indeed, a unit increase in SOC results in a 6-12% increase in the likelihood of having high QoL for all domains, however social support had more influence on nurses' QoL than their ability to cope with stress [2].

Stress and Burnout
Yam et al. analyzed SOC and perceived stress with a sample of critical care nurses, finding that SOC was a protective factor in relation to stress perceptions arising from the work environment [19].
Höge et al. investigated the possible impact of SOC and negative affectivity on the relationship between work stressors and strain. They found a strong correlation between SOC and negative affectivity [20].
Berg et al. [21] observed that Work-Related Strain Inventory (WRSI), measuring the feeling of psychological strain in occupational setting, and factor involvement of the Satisfaction with Nursing Care and Work (SNCW) scale, negatively related to SOC.
Several studies negatively correlated SOC with overall stress [8,20] and work-related stress [8], especially workload [22]; in these studies, nurses' overload in the workplace was identified as a critical factor for stress development. Burnout and SOC were found to inversely correlate in several studies [22][23][24][25].
Moreover, burnout subscales were observed to logically relate to SOC. A stronger coping ability is associated with higher scores in personal accomplishment, lower levels of emotional exhaustion, and depersonalization [8,15,26,27]. Workload was considered a major contributing factor for burnout [8].

Individual Characteristics
Five studies investigated the correlation between SOC and age, with discordant results: two studies [11,28] revealed a positive association between SOC and age of the participants, whereas another three studies [7,8,29] did not find this relationship significant. Nevertheless, in the study conducted by Debska et al., although no significant correlation was found between total SOC and age, an inverse association between age and Manageability subscale was observed [6].
Although one study did not find any correlation with sex of the participants [26], an earlier study by Lewis [8] observed a stronger SOC in women, compared to men.
SOC was associated to marital status in the study conducted by Tselebis et al. [26], whereas the same correlation was not found in other studies [8,9]. Educational background, considered by Kretowicz et al. was found to be positively associated to overall SOC and Meaningfulness [7]. Two studies by Debska et al. and Lewis et al. have not proven the same correlation [6,8].

Individual Physical and Mental Health
The relationship between SOC and nurses' health was the focus of several studies. Miyata et at. associated positively SOC with good mental health status and good physical health status [9].
Schäfer et al. observed a significant increase from the cut-off value of nurses' scores in ICD-10-Symptoms Rating (ISR), evaluating general health problems, as well as symptoms burden, depression and eating disorder symptoms. Moreover, when compared to physicians, nurses reported higher ISR and symptoms burden scores, the same was not found for variables such as Resilience, SOC or LOC (Locus of Control). Furthermore, SOC, Resilience, and Internal and External LOC correlated with ISR scores and Post-Traumatic Stress Disorder (PTSD) symptoms, correlating SOC as a significant predictor of mental health problems and of symptom severity [30].
An inverse correlation was found between health risk and SOC, the latter significantly affecting sickness-absences, especially for experienced and expert nurses, for whom it is the only casual factor, among the other investigated variables [14].
Depression and SOC have been found to negatively, and strongly, correlate in several studies [11,26,28,31]. Takeuchi et al. also considered the interaction of SOC and work-family conflicts (WFC) on the degree of nurses' depression and pointed out the buffering effect of SOC against depression, resulting from WFC [31].
Moreover, an inverse correlation was found between SOC and personal stress [22] and cumulative fatigue [31].

Personality Traits and Characteristics
Van der Colff et al. showed that SOC was correlated positively with different coping strategies, evaluated through the Coping Orientation for Problem Experienced (COPE) questionnaire, namely Approach Coping (seeking emotional/social support) and Turning to Religion; the correlation was inverse for Avoidance and Focus on and ventilation of emotions [15].
Overall a higher SOC score was associated with stronger total coping resources [22], thriving and the use of GRRs [1] and greater self-motivation, measured by the Self-Motivation Inventory (SMI) [32].
SOC was positively related to perceived progress goal as well as perceived control, both related to the perception of characteristic tasks of the job and life activities in which nurses were involved, evaluated upon interruption signals. Such signals were found to have a lower positive affect and higher negative affect in nurses with lower SOC [33].
Few studies concentrated on the relationship between SOC and personality traits. Kikuchi et al. revealed that SOC had a strong correlation with almost all personality traits, the strongest being the one with Neuroticism [11]. Höge et al. underlined the same concordant relationship between SOC and Negative Affectivity [20]. Similarly, SOC was found to correlate to the Karolinska Scale of Personality (KSP): negatively to Impulsiveness, Monotony Avoidance, Detachment, Hostility and Psychasthenia, and positively to Socialization and Empathy [23].
The KSP variable "Somatic Anxiety" was inversely related to SOC [23], but in contrast, no differences in mean SOC between the Anxiety (+) and the Anxiety (−) groups were found by Yoshida et al. [34].

Negative Life Events
In two different studies Hochwälder et al. investigated the association of negative life events on nurses' SOC [29,35]. There was no strong evidence that negative life events lower SOC in the sample population, but those who experienced a negative life event had initially a weaker SOC, compared to those who did not experience any negative life events [35]. Although there was not a significant correlation between SOC and the number of uncontrolled negative life events, those with high and moderate SOC reported fewer controllable negative life events compared to individuals with low SOC [29].

Intervention Studies
A total of six studies analyzed the effect of an intervention on nurses' Sense of Coherence. Only two studies observed a significant improvement in the SOC scores [36,37]. In the first study, nurses participated in a modified version of the Mindfulness-Based Stress Reduction (MBSR) program, lasting two weeks. After the intervention, it was observed a significant decrease in GHQ and its subscales (Physical Symptoms, Anxiety/Sleep, Social Activities and Depression), indicating an overall improvement in general health. Furthermore, SOC increase was significant, compared to the control group, as it was the increase in the meaningfulness subscale score, compared to comprehensibility and manageability scores [36].
Sarid et al. investigated the effect of Cognitive-Behavioral Intervention (CBI), comprised of 16 meetings, once a week, on nurses' SOC. At baseline the two groups did not differ in respect to SOC, perceived stress and mood states [37,38]. At T2 (four months after the beginning, upon completion of the program), nurses of the intervention group scored higher in SOC and vigor scales, whereas reported decreased level of perceived stress and fatigue. Such changes were not reported in the control group.
Nurses in the study conducted by Shimizu participated in an Assertive Training program. Although no significant changes in SOC were reported, the effects of the intervention were appreciable as an improvement in Self-esteem scores in the sample analyzed [39].
Berg 1999 and Pålsson 1996 both investigated the outcomes of systematic clinical supervision strategies on nurses. The two studies did not report significant changes in SOC after the intervention [21,23].
Only one study observed a reduction of mean SOC scores of nurse managers in early years of their supervisory roles, after the participation in a four-month experiential learning-based program [40].
The effect of an IT support project on SOC was considered in one study: no significant within-subject effects for the total SOC scale and meaningfulness subscale was observed both in the group receiving the intervention and the control group. However, IT support improved the perception of psychosocial job satisfaction and the quality of care; in this sense the study showed a significant interaction effect for the family relation factors, close friend relation (LSQ), total SOC scale and meaningfulness subscale [41].

Discussion
The nursing profession is characterized by taking care of patients and their families, it is a factor increasing the mental and emotional burden, and for this reason nurses' Sense of Coherence needs to be strong enough to deal with several stressful working experiences. Among others, most of the strain experienced by nurses derives from heavy workload, unsatisfactory work environment and work conditions, deep emotional involvement in others, organizational structure, lack of resources, inter-professional conflicts and professional uncertainty [21].
The majority of nurses spend more time at work than on their private life and report significantly higher SOC scores for those whose percentages were proportionally lower, and the lowest scores were for nurses with higher percentages of time spent on working activities [2,17].
Nurses face moral distress and feel so powerless because of the management policy of institutions [13]. The crucial role of institutions in cooperating in the hospital management is also correlated to a positive perception of safety, which in turn is correlated with absence of burnout and a strong Sense of Coherence [24].
The raising of SOC and organization environment reduces sickness-absence. Improving comprehensibility by enriching professionalism, recovering meaningfulness and manageability through optimizing work-life balance and social support may also raise SOC.
SOC and social support were found to be significant predictors for all QoL domains. Social support had the most relevant influence on nurses' QoL and is considered as a buffer in the stressful situations of healthcare working environment to help the individuals to cope. Cultivating social support could indeed help the individuals to improve their coping abilities and their general health status [2].
Occupational stress is a major contributing factor to burnout [15]. This correlation is also supported by studies, showing that individuals with high burnout levels are expected to possess poor stress coping abilities, specifically in the manageability dimension of the Sense of Coherence, which was found to be related to emotional exhaustion of burnout [15]. Burnout is defined as a syndrome of emotional exhaustion, depersonalization and decreased sense of self-achievement, unfortunately, occupational burnout affects a considerable proportion of nurses who face daily stress experienced at work [25].
Despite the relative stability of SOC after the third decade, it may be shaped progressively throughout the whole course of someone's life and the GRRs [42], which are mobilized by the Sense of Coherence, arise from the cultural, social and environmental conditions of living, in addition to idiosyncratic factors [43]. This concept could explain why the analysis of the correlation between SOC and individual characteristics (age, sex, marital status and educational background), taken into account only in few studies, yield discordant results.
An interesting point was explored by Kretowicz et al., who correlated positively SOC and educational background: as SOC is considered to have an educational value and the progress in the academic education could elevate it, it is reasonable to think that this relationship could influence task completion in managerial positions [7].
Furthermore, Antonovsky did not exclude a possible influence of negative life events on SOC, especially for those with low or moderate SOC [42]. Starting from this assumption, Hochwälder et al. in two different studies [29,35] have investigated this relationship: no association was found between negative life events and nurses' SOC, however those who experienced a negative life event had initially a weaker SOC, compared to those who did not experience any [35]. This result led the authors to consider a low SOC as a vulnerability factor, rather than considering a high SOC as a protective factor. This finding is in accordance with Antonovsky's assumption that a high SOC could prevent the experience of negative life events, both helping individuals to avoid potential stressors and not allowing them to perceive them invariably as negative [4].
A strong SOC is believed to be related to general well-being [15]. This relationship was confirmed by Miyata et al., who demonstrated in nurses a positive association between SOC and good mental health status and good physical health status [9].
Moreover, nurses working in hospitals reported, compared to the general population, higher burden of general health problems, as well as symptoms of burden, depression and eating disorders symptoms. SOC was found to be the most important predictor for general mental health problems and post-traumatic stress symptoms. SOC could play a crucial role in the development and course of these health issues, by shaping the perception and attitude toward aversive work experiences and stress [30].
The inverse relationship between SOC and health risk and the identification of SOC as a key determinant of sickness absences demonstrates how a poor coping ability, in the presence of powerful stressors, such as advanced career levels, could represent a health risk, due to a decreased ability to cope successfully with the stress. Nevertheless, Ida et al. advanced the possibility that raising SOC and the organization of the environment could produce a positive effect on sickness absences [14].
The inverse correlation between depression and SOC was strong in several studies [26,30,31]. Possession of a strong SOC allowed nurses to better manage occupational stress due to lack of organizational support and job demands, through the choice of appropriate coping strategies [15], to define themselves as thriving, with a positive use of GRRs [1] and to possess a greater self-motivation [32]. Self-motivation was found related to certain specific behavior attitudes (propensity toward physical activity and giving it value in respect to health) and the hypothesis of Langius et al. of a positive relation to SOC was confirmed by their investigation [32].
Only two studies investigated the correlation between anxiety and SOC. Yoshida et al. confronted two groups, divided based on anxiety presence, assessed by an ad hoc questionnaire: no differences were found among the two groups, possibly explained by the initially high SOC possessed by the group at hand [34]. Palsson et al.'s finding indicated that there is an inverse relationship between self-rated pathogenic anxiety and self-rated salutogenic Sense of Coherence [23].
Among the five studies investigating the effects of an intervention on the SOC, only two studies reported significant results. Stress coping strategies improvement, achieved by the MBSR therapy was demonstrated by a significant increase in SOC scores. Moreover, a significant increase in the Meaningfulness subscale of SOC indicated that, through the program, nurses were able to focus their attention on mind and body, allowing them to find meaning in their life and work activities [36].
The effects of CBI were significant in increasing SOC and vigor levels and in decreasing perceived stress and fatigue. CBI aims to raise the personal awareness on possible stress reaction, to learn how to self-talk in anxiety-producing situation, to gain a balance and awareness on perspective stressful events and to facilitate cognitive restructuring of stressful work situations. These intrinsic characteristics of the therapy explain the improvement in nurses' coping ability and the reduction of negative moods [37,38].
The only study reporting a decrease in mean SOC score investigated the changes produced by an experiential learning-based program. This result was explained by the overload experienced by nurse managers in early years of their supervisory roles when discussing their behavior and stressful situation encountered at work. Furthermore, it has been argued that SOC could possibly increase after an initial decrease, which was not evaluated, due to the short-term follow-up performed [40].
The other intervention studies did no show significant changes on SOC, these results are coherent with the initial description of SOC by Antonovsky, for whom SOC tends to remain stable in adulthood under normal circumstances and can be considered as a moderating factor on negative work environment variables [21]. Moreover, also the well-recognized difficulty in obtaining a significant SOC change in respect to high or low baseline is considered a determining factor of SOC stability in these studies [23].

Conclusions
SOC provides a solid theoretical basis for examining the organization of work [32]. Therefore it has been proposed that nursing management could focus on building a healthy work environment, which fosters SOC, rather than concentrating on resolving the effects of stress and its management at individual level [33].
Comprehensibility is improved by a clear view on roles and responsibilities and by open communication channels; sense of manageability is strengthened by appropriate workload and availability of resources [8,22]. Participation in decision making and the perspective of a clear career path are factors improving the sense of meaningfulness [8,33].
We found that SOC was a protective factor for depressive state, burnout, job dissatisfaction among female nurses, but there is no clear correlation with factors such as working experience or position at work. In addition, a higher SOC enhances a good mental and physical health status, acting as a health promoting resource, according to Antonovsky's theory [44,45].