Police officers are exposed to various traumatic and stressful events such as violence, witnessing traffic accidents, and life-threatening events [1]. The number of people per police officer in Korea as of 2015 was 426, which was quite higher than that in advanced countries, and the occurrence of violent crimes has increased. Some police officers who experience a traumatic event might develop post-traumatic stress disorder (PTSD) symptoms [2]. Further, it has been reported that prevalence rates of PTSD symptoms among police officers are between 7 and 19 % [1, 3].

However, not everyone who experiences a traumatic event develops PTSD symptoms. In particular, the risk level of PTSD symptoms among police officers is diverse [4]. Individual adaptability to traumatic events or stressful situations can serve as a psychological factor related to the prevention of PTSD symptoms. The term self-resiliency was first used by Rutter in 1985 [5] after he discovered that some people easily adapt to environmental difficulties and stressful situations, and has been used since. While resilient people can easily adapt to stressful situations, non-resilient people become impulsive and threatening; they overly control their demands and impulses, feel anxiety, and show signs of non-adaptability. In a study conducted on college students to examine the relationship between self-resilience and adaptability, it was observed that those with resilience, good interpersonal skills, and an ability to control their emotions had lower levels of anxiety and aggression compared to those who did not have these abilities. Self-resilience has positive effects on mental health [6]. Resilient people feel less stressed, are less lonely, have better social adaptation skills, and experience greater psychological comfort [7]. Based on these findings, it is determined that self-resilience-related factors lower maladjustment and affect the occurrence of PTSD symptoms in those who have experienced a traumatic event directly or indirectly.

Numerous studies have been conducted on protective factors for PTSD symptoms in people with special occupation. Besides the most salient predictor of PTSD symptoms, which is the nature of the traumatic event per se, three other risk factors were consistently identified across studies in a meta-analysis by Brewin et al. [8]: psychiatric history, family history, and mental disorders. In addition, personality traits (for example, hostility, neuroticism, positive world assumptions, and better social functioning) were also identified as predictors of PTSD symptoms [8–10]. However, relatively few studies have been conducted on the relationship between self-resilience and the occurrence of PTSD symptoms. Most of studies have been focused on firefighters. In particular, there are almost no studies related to resilience mediated mental health of police officers conducted by correcting for their occupational factors. However, there are differences between firefighters and police officers with respect to the intensity, frequency, and types of cases that they handle. It is generally known that firefighters face more intense cases, and as such, most of the studies to date have focused mostly on firefighters. Even if their degree of exposure is considered to be relatively mild, police officers who experience various forms of traumatic events can certainly be considered a high risk group for PTSD, and since studies on police officers are almost non-existent, additional studies on them are deemed necessary.

Therefore, this study was conducted on police officers in the Gangwon area, who experienced traumatic events, to examine whether self-resilience could serve as a protective factor against the occurrence of PTSD symptoms. Their general, occupational, and psychological characteristics were corrected for, and the relationship between self-resilience and the occurrence of PTSD symptoms was examined.

Although exposure to trauma is common, PTSD symptoms and other mental disorders after trauma are relatively rare. In order to allow early intervention, the core methodological objective of research on traumatic stress is to determine factors that might have a role in psychopathological symptoms leading to PTSD symptoms. These efforts are particularly essential for professional populations at high risk for trauma-related disorders (for example, police officers, firefighters, and military personnel who are regularly engaged in traumatic events). The present study aimed to identify the mechanisms underlying the interactions among risk and protective factors (such as self-resilience) related to PTSD symptoms. This study suggested that the association between traumatic exposure and PTSD symptoms might be moderated by an individual’s resilience. The results of the multivariate logistic regression analysis show that a low level of self-resilience is a strong predictor of development of PTSD symptoms in police officers who are exposed to traumatic events.

The present data support and extend the clinical evidence regarding the role of personality traits in PTSD symptoms. In the study, self-reliance scores were processed continuously, and it was observed that self-reliance was negatively correlated with the occurrence of PTSD symptoms. We also analyzed CD-RI-K score categorized into four and five groups in each and found no significance. Based on the average score of firefighters from an existing study (CD-RI-K score = 64.5), self-reliance was categorized into two groups. The low self-resilience group whose CD-RI-K score was below 64.5 had a high occurrence rate of PTSD symptoms. In the present study, participants with PTSD symptoms showed low self-reliance scores similar to a previous study based on firefighters. Many studies have examined the protective or predictable factors for PTSD symptoms [16–18]. Several studies have shown that not all individuals exposed to a trauma develop PTSD symptoms and that some are able to manage and cope with adversity; such findings indicate the importance of resilience as a protective factor [19, 20]. Resilience can be defined as the ability to adapt and successfully cope with acute or chronic adversity. Resilience reduces susceptibility to depression and suicide in individuals with childhood trauma [21, 22] and in veterans [23]. Furthermore, lower levels of self-efficacy have previously been related to PTSD symptoms [24–26]. Lower self-efficacy levels were observed in individuals with PTSD symptoms compared to healthy subjects; however, traumatized individuals without PTSD symptoms did not differ in self-efficacy levels compared to healthy subjects [26]. These findings illustrate the importance of individual’s resilience as a protective factor against PTSD symptoms in high-risk groups; however, recent models of resilience include risk as well as protective factors that may interact to reduce negative consequences and facilitate positive ones [27]. In this context, a better understanding of pre-traumatic risk factors would certainly have important clinical implications regarding the development of trauma-related disorders. Self-resilience is known to be one of the buffering factors for personal stressors, but might also play a leading role in preventing PTSD symptoms, if under organized control. Although not analyzed in this study, self-resilience can be developed by interventions in the workplace through communication, mutual respect, and dissolution of interpersonal conflict. Further prospective, longitudinal design studies examining resilience/intervention in the workplace are needed.

This study has several limitations that should be noted. First, the cross-sectional design of this study limits its ability to confirm a causal relationship among the variables that were investigated. Thus, the results of the present study should be interpreted cautiously, and future research using longitudinal and experimental designs is needed to clarify the direction of any causal relationships among the observed variables. Second, the present research relied solely on self-reported questionnaires. Although we have conducted the study on those who have not experienced traumatic events for the past 6 months and without any underlying mental disorders, we could not exclude subjects who might have had mild symptoms of PTSD already or short duration (less than 1 month) of PTSD symptoms. Moreover, we have not assessed the characteristics of their exposure: intensity, interval, and frequency of critical incidents. Future studies utilizing standardized interviews or observational methods would provide a more accurate and detailed information regarding the complex mechanisms underlying the relationship between traumatic stress and development of PTSD symptoms. Third, we could not consider multiple mechanisms involving protective psychological factors (for example, social support and self-efficacy), other personality factors, and possible underlying neurobiological mechanisms (for example, neuropeptide oxytocin), which could influence PTSD symptoms. There were also some elements missing from the analysis for the occupational factors, our survey did not include the exact type of job title, department, the frequency of emergent dispatch, case experience, and case types, and thus, this information was not reflected in the study. There were limitations associated with not taking into account the aforementioned factors, which can have a major impact on onset of PTSD symptoms. Finally, the present study included only a few participants. For this reason, future studies with a large number of participants are needed to achieve statistical significance for generalization of the current results. However, 2015 was the first year of our study based on police officers; they will be followed up for annual medical screening and examination, and we plan to conduct a cohort study on the health of police officers in Gangwon. Further, we will investigate various factors, which could influence PTSD symptoms. Future longitudinal studies will be conducted that include a large number of study subjects.

Despite the limitations, to our best knowledge, the current study is the first to identify the protective effects of self-resilience against the development of PTSD symptoms in police officers after adjusting for occupational characteristics. Although the reported results need to be replicated to draw concrete conclusions, self-resilience as a protective factor might eventually help clinicians and specific organizations to target individuals who are at a high risk of developing trauma-related disorders (for example, police officers, firefighters, and military personnel). In particularly, additional studies on police officers would be actively pursued based on the fact that for general occupational groups those have low exposure intensity, data from studies on police officers may actually be useful. Identification of protective or risk factors might provide clues regarding the underlying mechanisms and could help in building new strategies to prevent the development of a disorder [28]. Finally, the results might indicate that a coping skill training (for example, self-resilience training) could be helpful for primary and secondary prevention in populations at high risks.