Among healthcare providers, nursing is a stressful and compassionate profession. Nurses empathetically support patients with pain, loneliness, disease and even confronted with death in line with their critically physical, mental, emotional, and spiritual needs and provide comfort, help, presence for them. Because nurses are frequently exposed to highly stressful and emotional situations, they suffer compassion fatigue (CF) over time under repeated exposures. CF will have a series of physiological, social, emotional, spiritual, and cognitive effects on nurses, threatening the existential integrity of them. The effects include high rates of anxiety and depressive disorders, decreased productivity, increased clinical errors, decreased quality of care and level of job satisfaction. Therefore, it is particularly important to pay attention to compassion fatigue to maintain mental health of nurses.

Compassion fatigue refers to that in the process of providing assistance, the helper bears the pain of the recipient due to empathy, which reduces the helper's own energy or interest.Based on a widespread conceptual model, CF consists of two constructs: burnout and secondary traumatic stress. Nurses are at a great risk of compassion fatigue. CF is gradually becoming a serious problem which can affect nurses' physical and psychological health, performance, job satisfaction and quality of care . Thus, investigating the prevalence of CF among nurses and its related factors are warranted to prevent CF among nursing population.

Research has studied the influencing factors of CF. Some studies have found that the demographic characteristics, worked related factors , the degree of exposure to traumatic events and psychological factors are important factors affecting nurses' compassion fatigue. Some studies suggest that resilience, social support, sense of control and meaningful recognition are negatively correlated with CF . Among them, resilience and self-efficacy are considered as important psychological factors affecting the individual's mental health, and they play an important role in the occurrence of CF.

The working pressure of clinical nurses comes from the situations that they are exposed to patients' traumatic events and give excessive empathy for a long-term. CF among nurses is an undesirable outcome caused by maladaptation to this pressure. What's more, resilience, and self-efficacy play an important role in individual coping and psychological adjustment in face of stressful events. Therefore, it is necessary to explore the roles of resilience and self-efficacy in the process of CF.

According to the theoretical path analysis of professional caregivers' quality of life, work environment, client environment and person environment factors have an influence on the development of compassion fatigue . Regarding to the psychological stress system , When confronted with stressful events, the individuals will have a stress response as a joint result of environmental factors and personnel factors. Thus, in accordance with the above two theories, being exposed to traumatic events is considered as a stressor, which could lead to CF. During this process, several external factors (work-related environmental factors) and internal factors (personality, social support) have effects on CF. In this study, resilience, and self-efficacy will be recognized as individual psychological characteristics and CF will be treated as a psychological change. Although there have been several studies on the predictors of CF in nurses around the world, limited knowledge exists in considering both internal factors (resilience and self-efficacy) and external predictive factors (demographic, work-related factors) of CF among nurses, especially in mainland China.

The study aims to investigate the level of compassion fatigue among Chinese nurses and test the influences of demographic characteristics, work-related factors, resilience, and self-efficacy on compassion fatigue.

This study adopted a cross-sectional design. It was executed in accordance with STROBE Statement: guidelines for reporting observational studies.

Through convenience sampling, clinical nurses from different departments were recruited from three tertiary hospitals in central China.

According to the calculation method of the sample size regarding to the linear multiple regression, fixed model in G power software 3.1 was used. In this calculation, effect size f2=0.15, α= 0.05, 1-β=0.95, the study included 13 demographic variables, resilience and self-efficacy, 15 independent variables in total. The sample size calculated by G power software 3.1 is 199. Considering the 20% loss to follow-up rate and sampling error, the sample size was expanded to 239.

Measurement The general information questionnaire The social-demographic questionnaire was self-compiled and aimed to collect participants' demographic characteristics such as age, gender, educational level, marital status, working department, years of nursing experience, professional title, monthly income, shift work and physical conditions and so on.

Professional quality of life scale (Chinese version; ProQOL-CN) The Professional quality of life scale was used to evaluate the level of compassion fatigue. The original version was developed and then translated to Chinese. The scale has 30 items with three subscales including compassion satisfactory , burnout and secondary traumatic stress . Together, these latter two subscales measure compassion fatigue. A five-point Likert scale was used (1 = "never" to 5 = "very often") . A higher score of the compassion satisfaction subscale represents a higher level of compassion satisfaction, while a higher score of the burnout and secondary traumatic stress subscale indicates a higher risk of burnout and secondary traumatic stress. The score of each subscale lower than 22 represents a low level of compassion satisfaction, burnout, and secondary traumatic stress; score between 23 - 41 indicates an average level; and more than 42 suggests a high level . The Cronbach's alpha of the scale in this study was 0.722.

Connor-Davidson resilience scale (Chinese version; CD-RISC) The CD-RISC aimed to measure participants' resilience. The Chinese version of CD-RISC consists of three dimensions (tenacity, strength, and optimism) with 25 items. A five-point Likert scale was used (0 = "never" to 4 = "almost always"). The scale can effectively measure the resilience among clinical nurses and has good reliability and validity . The reliability of the CD-RISC among Chinese residents was 0.91 and the Cronbach's alpha of the scale in this study was 0.966.

General Perceived Self-Efficacy Scale (Chinese version; GSES) The GSES was used to measured participants' self-efficacy . The Chinese version consists of 10 items assessed by a four-point Likert scale (1=incorrect to 4=correct). The total scores range from 10 to 40, with higher total scores indicating higher levels of self-efficacy. The Cronbach's alpha of the scale in this study was 0.941.

Procedures Data were collected from 3rd October, 2019 to 15th December, 2019 and the data collection was completed by a researcher and two research assistants. First, the researchers informed the directors and head nurses from each hospital of the study's purpose and got their permission to recruit nurses. Then, researchers introduced the contents of the questionnaires to research assistants in the hospital and explained how to complete it. Lastly, researchers distributed a Wenjuanxing link (an online crowdsourcing platform in China) involved the electronic research questionnaires by scanning a Quick Response code to research assistants. According to the inclusion criteria, nurses who had interests could contact the researchers and research assistants in hospital to participate in the study. Wenjuanxing is a relatively secure platform and there is no risk of any data breach and leakage by a third-party.

Inclusion Criteria:

• The hospital is a comprehensive hospital;
• Nurse have been registered and are on their duty;
• Nurses are currently engaged in clinical practice;
• Nurses are willing to participate in the study.

Exclusion Criteria:

• Nurses who are intern nurses or studying in other hospitals, or has been participated in other relevant studies.

According to the calculation method of the sample size regarding to the linear multiple regression, fixed model in G power software 3.1 was used. In this calculation, effect size f2=0.15, α= 0.05, 1-β=0.95, the study included 13 demographic variables, resilience and self-efficacy, 15 independent variables in total. The sample size calculated by G power software 3.1 is 199. Considering the 20% loss to follow-up rate and sampling error, the sample size was expanded to 239.

The process of data collection cost a lot of human and material resources, some of the data was privacy information of participants, and so on.Considering this, it is improper to share these data.