*2.2. Articles Selection*

Two independent reviewers selected the studies according to the following inclusion criteria: (1) original articles, and (2) administration of the SOC questionnaire to a sample of formal nurses.

Exclusion criteria applied were: (1) SOC questionnaire not administered, (2) language other than English, (3) sample different from working nurses (nurse teachers, unemployed nurses), (4) impossibility to retrieve a specific SOC value for the nurse sample, (5) absence of both mean SOC value and type of SOC questionnaire, and (6) use of other SOC questionnaire other than SOC-29 or SOC-13. Disagreements on article selection were resolved by consensus.

#### *2.3. Data Extraction and Synthesis*

Extraction of paper's data was independently performed by the reviewers through a pre-set table and consensus was reached, upon common revision, for each item inserted therein.

Selected papers were subsequently divided into three categories, based on whether the field of investigation of the Sense of Coherence was work-related or within the individual's sphere; articles assessing SOC variation upon interventions were categorized separately. The categories were named "Work-Related Variables", "Individual Variables" and "Interventions".

#### **3. Results**

A total of 876 papers were obtained. After duplicates removal, 535 records were screened initially by title and abstract and then by full text assessment. This process led to the exclusion of *n* = 454 and *n* = 42 articles respectively, yielding a total of 39 records included in the present review (Figure 1).

**Figure 1.** Flowchart of the searching and screening of literatures.

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.

**Figure 2.** Flowchart of the allocation into the three categories: "Work-related Variables", "Individual Variables", "Interventions".




**Table 1.** *Cont.*









149


*IJERPH* **2020**, *17*, 1861

**Table 1.** *Cont.*

150


**Table 1.** *Cont.*











**Table 1.** *Cont.*

#### *3.1. Work-Related Variables*

#### 3.1.1. Job Characteristics

Debska et al. observed among the nurses highest SOC scores for the Manageability subscale (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].

#### 3.1.2. 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].

#### 3.1.3. 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].

#### 3.1.4. 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].

#### 3.1.5. 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 [22–25].

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].

#### *3.2. Individual Variables*

#### 3.2.1. 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].
