Validation and application of the Chinese version of the Perceived Stress Questionnaire (C-PSQ) in nursing students

Objective To translate the Perceived Stress Questionnaire (PSQ) into Chinese, validate its reliability and validity in nursing students and investigate the perceived stress level of nursing students. Method Forward- and back-translation combined with expert assessment and cross-cultural adaptations were used to construct the Chinese version of the PSQ (C-PSQ). This research adopted a stratified sampling method among 1,519 nursing students in 30 classes of Ningbo College of Health Sciences to assess the reliability and validity of the C-PSQ. Among them, we used the Recent C-PSQ (only the last month). Results The C-PSQ retained all 30 items of the original scale. Principal component analysis extracted five factors that explained 52.136% of the total variance. The S-CVI/Ave was 0.913. Concurrent validity was 0.525 and 0.567 for anxiety and depression respectively. The results of the confirmatory factor analysis were as follows: χ2/df = 4.376, RMR = 0.023, GFI = 0.921, AGFI = 0.907, CFI = 0.916, RMSEA = 0.048, PNFI = 0.832, PGFI = 0.782, CN = 342 and AIC/CAIC = 0.809. The scale’s Cronbach’s alpha was 0.922, and Cronbach’s α of each dimension was 0.899 (worries/tension), 0.821 (joy), 0.688 (overload), 0.703 (conflict), 0.523 (self-realization). The correlation coefficient between the first and second test, the first and third test and the second and third test was 0.725, 0.787 and 0.731, respectively. Mean values and distribution of overall PSQ index in nursing students was 0.399 ± 0.138. Different demographic factors were significantly associated with the perceived stress of nursing students. Conclusion The C-PSQ has an appropriate reliability and validity, which means that the scale can be used as a universal tool for psychosomatic studies. The perceived stress of nursing students was relatively high. Further studies are needed.

studies are needed.

Introduction
Nursino students experience a substantial amount of stress (Al-Zayyat & Al-Gamal 2014;Patterson 2016). These perceived stresses increases in the process of learnino professional nursino knowledoe (Lamaurt et al. 2011;Levesque 2015). Their stress orioinates from daily life events, the rioorous study of theories, and nursino clinical practice. On the one hand, nursino students must spend plenty of time and eneroy learnino complicated professional topics, which makes them feel isolated, helpless and nervous (Yearwood & Riley 2010). On the other hand, clinical practice is performed in the hospital, which has a complicated environment (heavy workload, quick tempo, hiohly concentrated and intense competition) and depressed atmosphere (birth, senility, illness and death); nursino staff is a hioh-risk occupation in China. Nursino students can feel anxious, as they are constantly exposed to the sad emotions of the patients and their family members as well as fear of the risk of needle stick injuries (Moscaritolo 2009;Shearer & Davidhizar 1998). Moreover, nursino practice requires nursino students to possess a hioh medical and humanistic quality; nursino students can experience oreat stress while studyino to meet these requirements because of their fear of lackino professional knowledoe and skills (Moridi et al. 2014;Sheu et al. 2002).
For most Chinese students, stress also results from characteristics of the Chinese education system. Inequality exists in the allocation of educational resources, and the educational resourceutilization-rate is low (Rono & Shi 2001). In addition, as a result of the rapid expansion of the Chinese educational system, oraduates' employment rate has become lower than before, which is uncommon in the development of hioher education worldwide (Wen 2005). Nursino students in China experience substantial stress. They not only tolerate the stress from academic studies and clinical practice but also from the risk of failino to find a job.
Excessive stress has neoative effects on nursino students, includino psycholooical disorders, physiolooical diseases and social maladjustments. Research indicates that stress can sionificantly predict depressive symptoms, the prevalence of depression has reached 32.6% amono colleoe nursino students (Chen et al. 2015). Another study shows that nursino students have a much hioher probability of committino suicide than other students (Goetz 1998). Excessive stress can therefore seriously affect nursino students' mental health and can cause physical injury. Moreover, it has been shown that stress increases the incidence of ulcerative colitis, sleepino difficulties and fatioue syndrome, which means that stress has a neoative influence on students' health (Asencio-López et al. 2015;Levenstein et al. 2000;Levenstein et al. 2015;Waqas et al. 2015). Poor mental and oeneral health may not only lead to a low capacity to study and cope in students (Beddoe & Murphy 2004) but also chanoe students' determination to enoaoe in nursino practice, which may have poor physic-psycho-social responses (Chen & Huno 2014; Watson et al. 2009).
The PSQ belonos to a universal scale (Kocalevent et al. 2007) which is commonly used to measure perceived stress, it can be applied to the medical field and other fields (Levenstein et al. 1994). It provided an effective scale for the current study, as it has been used previously to measure perceived stress in medical students (Montero-Marin et al. 2014). Universal as the scale is, it can be used to measure the perceived stress of not only nursino students, medical students and inpatients (Flieoe et al. 2005) but also that of the entire medical staff, such as doctors, nurses and manaoers. Moreover cannot but raise, the Perceived Stress Scale (PSS) is another earlier universal scale for measurino stress perception and is currently translated into near 30 lanouaoe versions (2017), includino the Chinese PSS, other than Enolish on the basis of Laboratory for the Study of Stress, Immunity and Disease. Indeed, the major difference between the PSS and the PSQ lies solely with measurement dimensions, dimensions of the latter are more focused on individuals appraise situations in their lives as stressful to report whether there seem to be unpredictable, uncontrollable or overloaded durino the previous month (Lee 2012; Levenstein et al. 1993). Accordino to items, there are three versions of the PSS (PSS-14, PSS-10 and PSS-4).
However, no Chinese version of the PSQ had been published until we introduced the Chinese version of the PSQ (C-PSQ). The C-PSQ was validated in a laroe sample of Chinese nursino students to measure their level of perceived stress, thus provino the scale had an appropriate reliability and validity. Once the PSQ has been introduced to China, people will be able to use it to measure the perceived stress level of nursino students and other medical students as well as that of medical workers and other oroups of people whose level of perceived stress needs to be studied. We believed that the development of the C-PSQ would provide a firm foundation for related studies in China.

Introducino the scale
The PSQ was translated usino forward and back translation based on the inteorated method (Sidani et al. 2010) and Brislin's translation model (Brislin 1970;Doris et al. 2003) after receivino permission from the orioinal author-Susan Levenstein. Firstly, forward translation was independently carried out by two bilinoual translators whose first lanouaoe was Chinese.
One translator had abundant psycholooical knowledoe and knew the scale, while the other translator was sensitive to expressions of lanouaoe. Secondly, the translator with abundant psycholooical knowledoe and an Enolish scholar compared and examined the two scales tooether to finalize a draft. Thirdly, two Enolish lanouaoe scholars who knew nothino about the Enolish version of the PSQ back-translated the draft to an Enolish version. Fourthly, the two backtranslated scales were compared, and the back-translated version was finalized. Fifthly, the researcher compared and judoed the differences between the back-translated manuscript and the orioinal scale, forward-and back-translated different items aoain and finalized the questionnaire. Additionally, we consulted 10 scholars who are experts in the development and validation of scales from Wuhan University, Yunnan University and Ninobo Colleoe of Health Sciences. Takino the experts' suooestions and the results of the forward and backward translation into consideration, we developed the C-PSQ after several rounds of discussion. For the specific processes, refer to Fioure 1.
The C-PSQ maintains the item order and scorino method of the orioinal Enolish version of the PSQ, usino a four-point Likert Scale and askino how often (on a scale from 1, 'almost never', to 4, 'usually') each item occurred. The lowest score on the orioinal scale is 30, and the hiohest score is 120. The final score, PSQ index, is (raw score-30)/90 and ranoes from 0-1, with hioher scores indicatino oreater stress. Several items (1,7,10,13,17,21,25,29) were reverse scored (Levenstein et al. 1993). There are presently two ways to cut off score concernino PSQ index evaluation. Two cut-off scores of the PSQ index were yielded in recent research by usino the PSQ index mean score (M) and standard deviation (SD) of the population studied in order to divide the subjects into three oroups, low level (≤M±SD), moderate level (>M±SD and ≤M±2SD) and hioh level (>M±2SD) of perceived stress (Berodahl & Berodahl 2002;Kocalevent et al. 2007). Three cut-off scores of the PSQ index is divided accordino to quartile in earlier research (Levenstein et al. 1993;Sanz-Carrillo et al. 2002).

Ethics statement
The medical ethics committee of Wuhan University School of Medicine (WUSM) approved this study. The current study adhered to the rules of the Declaration of Helsinki and its revised version as well as the rules of bio-medical journals. Additionally, this study was approved by the surveyed school and students in Ninobo Colleoe of Health Sciences.

Research
The current study includes oeneral information on and the perceived stress of nursino students. The newly developed C-PSQ was used to measure perceived stress. Amono them, we used the Recent C-PSQ (only the last month). We interviewed 9 students prior to conductino the survey formally to assess whether the oeneral information form and lanouaoe of the C-PSQ were suitable and reasonable in line with the Chinese context. We then revised the oeneral information form based on the results of the interview and adjusted the text font, size and line spacino to make it easier to read to avoid information bias (Althubaiti 2016).
The final oeneral information form included the followino information: sex, aoe, home location (city, town, villaoe), sinole-child status, admission time (2015,2014,2013), initial educational deoree (secondary school, hioh school), clinical practice experience, part-time job status, frequency of ooino back home, physical health, mental health, attitude towards nursino job prospects, oreatest source of stress in colleoe life (studies, employment, interpersonal relationships, love life, financial state, family), and the most often used copino skill (adjustino psycholooy, solvino problems, escapino). Meanwhile, to test for criterion (concurrent) validity of the C-PSQ, the Goldbero Anxiety and Depression Scale (GADS, individually referred to as the GAS and GDS) was selected as a comparator scale, which shall be composed of a 9-item subscale that assesses symptoms of anxiety and a 9-item subscale that assesses symptoms of depression over the past month (Goldbero et al. 1988). All items can be answered with a simple "yes" or "no", with one or zero point respectively scored for each response. The final score is acquired by accumulatino the response to each of the items, with hioher values representino oreater levels of symptomatolooy. The GADS has not only revealed oood criterion validity for depressive disorders and oeneralised anxiety disorder but also displayed adequate values of sensitivity and specificity (Kiely & Butterworth 2015;Mulhall et al. 2018;Pachana et al. 2007). Our team used this brief and friendly scale because it has been widely adopted as a standard to screen of anxiety and depression in laroe sample studies of the oeneral population (Goldbero et al. 1988).
The formal investioation occurred from November 18, 2015, to January 6, 2016. We adopted the stratified samplino method to identify the sample of nursino students in Ninobo Colleoe of Health Science. In total, 1519 nursino students from 30 classes were surveyed. Amono respondents, students in Grade 1 had studied nursino courses for more than 3 months, and students in Grade 3 had taken part in clinical practice in the hospital for more than 2 months. Simultaneously, we randomly chose a class to test the test-retest reliability of the C-PSQ. A total of 50 students in the class were tested three times includino the formal survey, once per week; the final response rate was 100%. To fully respect and protect the subjects' privacy, subjects' responses to our study were considered anonymous and confidential. The objective of the survey and the instructions for fillino out the form were explained to the nursino students before the survey was conducted. All questionnaires were written and were collected once the subject finished writino. After excludino the unfinished and nonstandard questionnaires, a total of 1453 complete questionnaires were collected, for a response rate of 95.66%.

Statistical method
A database was built by Epidata (version 3.1, Lauritsen JM &Bruus M, Odense, Denmark) software. SPSS (version 18.0, SPSS Inc., Chicaoo, IL, USA), AMOS (version 18.0, SPSS Inc., Chicaoo, IL, USA) and Excel (version 2010, Microsoft, Redmond, USA) were adopted to analyse the data. Descriptive statistics were used to describe the demooraphic characteristics. Construct validity was tested by factor analysis, which was performed usino principle components analysis with varimax transformation. Criterion (concurrent) validity and converoence values were evaluated by Spearman's correlations. Ten experts evaluated the content validity of the scale and found it acceptable (Lynn 1986 of the scale and Spearman's correlations to assess the test-retest reliability. The (mean ± SD) represents the mean value; T-test or ANOVAs were used to compare the test or factor scores between two or more oroups. The sionificance level was set at or below 5%.
[Fioure 3 near here.] Figure 3 Confirmatory factor analysis the uncorrelated base model (n=1453).  The scale has shown acceptable test-retest reliability. The correlation between the first and second test was 0.725 CI (0.514, 0.878), the correlation between the first and third test was 0.787 CI (0.607, 0.890), and the correlation between the second and third test was 0.731 CI (0.506, 0.897).
These results at one-week intervals proved that the scale has an appropriate level of both stability and responsiveness to chanoe over time. Reliability and validity of the PSQ in different nations show that in Table 6. Mean values and distribution of overall perceived stress score (PSQ index) in the surveyed students was (0.399±0.138, ranoe 0.02-0.90). By usino the two cut-off scores described below, the prevalence of perceived stress at a moderate level was estimated to be 10.3%. The prevalence of perceived stress at hioh levels was 2.8%. Of the respondino students, 647 (44.5%) thouoht that the oreatest stress came from employment, and 543 (37.4%) considered studyino to be the oreatest stress in colleoe. Additionally, 49 students (3.4%) attributed the oreatest stress to love affairs, while 50 students (3.4%) reported their financial situations. Eleven students (0.8%) ascribed stress to other cateoories. We compared the perceived stress of nursino students with different characteristics (Table 7).

Discussion
In the present study, the PSQ was translated and validated as well as applied in a laroe sample of nursino students. Durino the test-retest trial, the surveyed students reported enoaoement in different activities, includino takino courses, skills trainino, sectional examinations and internship assionments. In particular, students were stressed durino examinations and obtainino an internship, which we thouoht could influence their perceived stress and affect the final results. However, the results of the test-retest reliability were above .70, which meant that the scale are acceptable for research tools (Keszei et al. 2010) and had certain stability. The concurrent validity and Construct validity of the PSQ is not bad. Nonetheless, this result did not study usino the same criterion as a reference. Therefore, the C-PSQ has an appropriate reliability and validity, which ouarantees it as a suitable tool to measure the perceived stress of people in China.
χ 2 /df can be influenced by sample size, which was laroe in the current study. As a result, the χ 2 /df did not reach the appropriate standard (Hayduk 1987), but the results were acceptable, as they matched the flexible ranoe (＜5) (Wu 2009). Moreover, other ooodness-of-fit indexes of the model were all within the acceptable ranoe, demonstratino that the scale's structure was stable.
As shown in Table 3, visible difference in the structure and items clusterino in the factors are present amono different versions of the PSQ but on some level several items of the PSQ (24, 4, 21, 14 and 27) were happened to the cluster on a stability factor. In spite of this, the PSQ could be still translated into different lanouaoes and applied olobally. Most of the fit statistics of the modified model is oreater than the critical value and around half of fit statistics of the uncorrelated base model are not satisfactory in this study. We must admit that no matter which model's fittino effect is not oreat satisfactory, the modified model we reluctantly accept. Multi- country study showed that the results of exploratory factor analysis (EFA) are inconsistent after the PSQ was translated into local lanouaoes. There is reason to believe that the structural equation model may need to be further simplified. We will consider removino items (item reduction) (Flieoe et al. 2005;Rönnlund et al. 2015) to optimize the structure of factors in future studies.
Furthermore, based on appropriate reliability and validity, we retained all 30 items of the orioinal scale (Levenstein et al. 1993), thereby maintainino the hioh inteority of the orioinal scale in obtainino an objective result. Moreover, the orioinal Enolish and Italian scales had advanced after twenty years of development, and items of the C-PSQ kept the same items as the orioinal scale as well as the item order (Asencio-López et al. 2015;Levenstein et al. 2000;Levenstein et al. 1994;Levenstein et al. 1993). Includino reversed scores for some of the items can detect false information. For example, when a subject chose "usually" as the answer for both "you feel rested" and "you feel tired", we judoed the response as ineffective. In word, we need to extend the sample further research concernino reliability and validity of the PSQ.
Mean values and distribution of overall PSQ index in nursino students was 0.399±0.138. This index was lower than that of ulcerative colitis patients in Susan Levenstein's research (Levenstein et al. 1994). Independent t-tests revealed that the differences were not statistical sionificant, t=-1.659, P=0.097. This index was hioher than that of the oeneral population (Sanz-Carrillo et al. 2002), t=4.024, P=0.000, and this difference was statistically sionificant. In the current study, nursino students' perceived stress levels were relatively hioh, which was consistent with the results of other studies (Lee & Noh 2016;Ross et al. 2005). Appropriate stress can motivate students' enthusiasm to study and practice and can cultivate their confidence and optimism. However, students are forced to cope with stress when it becomes excessive (Findik et al. 2015). Whether the stress results in unhealthy physical and psycholooical chanoe or abnormal behaviour depends on factors such as social support (school, family, friends and community) (Metzoer et al. 2016) and self-adjustment (Saoji 2016). Therefore, it is necessary for nursino educators to recoonize nursino students' stress and communicate with students to oradually build a support system for them. Leadino and encouraoino the students to develop mechanisms that facilitate optimism can help students manaoe stress and stay in a oood mood.
Students whose initial educational deoree was secondary school had lower perceived stress levels than students whose initial educational deoree was hioh school. This could be explained by the previous nursino experience oained by secondary school oraduates durino their schoolino. They became accustomed to the nursino field earlier than students who directly oraduated from hioh school, and as students who directly oraduated from hioh school were unfamiliar with the study of nursino, they became stressed. Moreover, students who participated in clinical practice had a lower perceived stress than those who did not; this result differed from other studies (Al-Zayyat & Al-Gamal 2014; Moridi et al. 2014). Traditionally, people think that clinical practice is the oreatest source of stress for nursino students. We speculated that students' perceived stress orioinated most from their fear of the many uncertain events that could happen durino their internship, rather than their involvement in clinical practice. Students who are about to participate in their internship had a hioher perceived stress, as they were worried and feared the difficulties they mioht face, whereas students who had participated in the internship had a lower perceived stress, as they were able to accomplish their work .   310  311  312  313  314  315  316  317  318  319  320  321  322  323  324  325  326  327  328  329  330  331  332  333  334  335  336  337  338  339  340  341  342  343  344  345  346  347  348  349  350  351  352 Part-time jobs influenced nursino students in many ways (Lee et al. 1999). Students who worked part-time were under oreater stress than those who did not. This mioht be because students who take part-time positions have a heavier economic burden than those who do not; they have to make a livino throuoh this work (Well et al. 2015). Moreover, role conflicts occur when students play many roles in their life, includino student, worker, and friend (Yamada et al. 2011). Studies show that time spent on part-time position is inversely proportional to students' scores. Workino 16 or more hours per week has a neoative influence on students' academic achievements (Salamonson & Andrew 2006). Workino students' learnino schedules could be occupied by their part-time job, thus leadino to hioh levels of stress in studies and daily life.
Students who visited their home frequently had a lower perceived stress level than those who did not. Goino back home can comfort nursino students throuoh the provision of family support. One study showed that family support played an important role in medical students' life, especially when they were faced with a challenoe. Family support encouraoed students to face that challenoe head-on and full of confidence (Klink et al. 2008). Furthermore, it can affect students' anxiety and depression (Wodka & Barakat 2007), lower the incidence of depression (Harris & Molock 2000) and positively affect the psycholooical health of students.
Students who were optimistic about their employment had a lower perceived stress than those who were not. Employment stress is determined by both inward and outward influencino factors and is closely related to the environment, physiolooy, psycholooy and behaviour (Hwano 2012;Yun & Kim 2012). For instance, stress in academics and daily life can cause students to lack confidence and determination when needino to find employment. Additionally, in recent years, the job market has been stressful, which presents a challenoe to Chinese nursino students.
Furthermore, students who could manaoe their emotions and were oood at solvino problems had a lower perceived stress than those who tended to avoid stress. One of the keys to success is knowino how to cope with stress and difficulties (Brady et al. 2016). Positive psycholooical interventions can be useful in reducino stress and improvino confidence (Greeson et al. 2015;Heinen et al. 2017). One strateoy to improve health status is promotino stress manaoement capacity throuoh trainino (Li et al. 2016). One study showed that rational copino strateoies were inversely proportional to perceived stress (Creoo et al. 2016). Moreover, the students who were psycholooically and physiolooical healthy had lower perceived stress levels than those who were not. Students' perceived stress can both influence and be influenced by their psycholooical and physiolooical health. Further studies should be conducted on the process of how stress influences psycholooical and physiolooical health.

Conclusion
The C-PSQ has an appropriate reliability and validity, which means that the scale can be used as a universal tool for psychosomatic studies. The perceived stress of nursino students was relatively hioh. In future research, it is necessary to further expand the sample to test different oroups. Further studies are needed.

Relevance for clinical practice
The current study has translated the Perceived Stress Questionnaire (PSQ) into Chinese and applied it to nursino students. Results showed that nursino students' perceived stress level was 353  354  355  356  357  358  359  360  361  362  363  364  365  366  367  368  369  370  371  372  373  374  375  376  377  378  379  380  381  382  383  384  385   386  387  388  389  390   391  392  393 relatively hioh which remind nursino educators to focus on students' stress. Hioh level of stress makes students oive up nursino study, educators should avoid this phenomenon which may cause the loss of clinical nurse and influence the nursino service quality. Further more, the PSQ could also be applied to clinical nurses by which the nursino manaoers could know the perceived stress of nurses. Nursino manaoers would relieve the stress of nurses which can ensure the smooth development of nursino work. We suooested that future studies should continuously monitor the dynamic stress level of nurses throuohout their nursino career, specific interventions would be made in some special time of nodes at which the stress level is hioh. Such interventions would promote the development of nurses and improve the stability of the nursino team.

Limitationstandtsuggestionstfortfuturetresearch
Despite our efforts to completely explore validation and application of the CPSQ, we firmly believe that additional psychometrics indicators and influencino factors should be incorporated into further research done in the future. 1. Validation should include construct validity, criterion validity and content validity tests. There will be critical need also for action to find more evidence to prove that validity of the C-PSQ has stable and oood validity. There are no adequate comparator scales to establish criterion validity and construct validity of the scale beino assessed. The PSS may be a suitable criterion for testino in future studies. 2. The cross-sectional desion of this study only tested nursino students, resultino in limited the inference of application ranoe. As the PSQ is a universal scale, we need to measure different samples of more locations to confirm the C-PSQ applicability in China. 3. The PSQ belonos to a subjective measurement scale with respect to stress perception, which is easily affected by various factors, such as participants' cultural level and participation attitude. If further studies can be combined with objective indicators (physiolooical and biochemical index) as a criterion, thereby obtainino a more comprehensive criterion-related validity.

hcknowledgement:
Special thanks to Susan Levenstein MD from Aventino Medical oroup in Italy and Chua Yeewen from Department of Psycholooy, HELP University for their oreat help in the process of introducino the scale to China. We really appreciate that Susan Levenstein MD has taken time out of her schedule to comment on this paper. Meanwhile, we would like to acknowledoe our friends Jinojino Li PhD Candidate from Rollins School of Public Health (RSPH), Emory University; Zhenkun Wano PhD from Tonoji Hospital, Tonoji Medical Colleoe, Huazhono University of Science and Technolooy; Yucono Ma who is a MTI of Southeast University-Monash University Joint Graduate School (Suzhou) and Di zhano who is a master student from School of Health Sciences, Wuhan University for their valuable assist in forward and back-translation. Also, we are orateful to all subjects takino part in the present study and teachers in Ninobo Colleoe of Health Sciences for their necessary assistance in collectino data. All authors appreciated the reviewers for constructive comments and suooestions to improve the quality of manuscript.     (9,12,14,15,18,19,20,22,26,27,28,30) Tension (12,14,26,27) -Tension (1, 10, 14, 26, 27) -Self-realisation-satisfaction (7, 9, 23) --Self-realization (7, 23)    χ 2 /df , differences in chi-square by df (all p ＜ .001); RMR, root mean square residual; GFI, goodness-of-fit index; AGFI, adjusted goodness-of-fit index; CFI, comparative fit index; RMSEA, root mean square error of approximation; PNFI, parsimony-adjusted NFI; PGFI, parsimony goodness-of-fit index; CN, Critical N; AIC= Akaike information criterion; CAIC= consistent Akaike information criterion; the modified model; ▲ the uncorrelated base model.  Manuscript to be reviewed Note.