Short version of the “instrument for assessment of stress in nursing students” in the Brazilian reality

ABSTRACT Goal: validate a short version of the Instrument for assessment of stress in nursing students in the Brazilian reality. Method: Methodological study conducted with 1047 nursing students from five Brazilian institutions, who answered the 30 items initially distributed in eight domains. Data were analyzed in the R Statistical Package and in the latent variable analysis, using exploratory and confirmatory factor analyses, Cronbach’s alpha and item-total correlation. Results: The short version of the instrument had 19 items distributed into four domains: Environment, Professional Training, Theoretical Activities and Performance of Practical Activities. The confirmatory analysis showed absolute and parsimony fit to the proposed model with satisfactory residual levels. Alpha values per factor ranged from 0.736 (Environment) to 0.842 (Performance of Practical Activities). Conclusion: The short version of the instrument has construct validity and reliability for application to Brazilian nursing undergraduates at any stage of the course.


Introduction
In the process of undergraduate nursing training, academic, clinical and socioeconomic factors can impact the academic performance and health of students. The overload of theoretical courses, the level demanded in tests and extra-class activities, the interpersonal relationship with teachers and the fear of not succeeding are common aspects of the academic context (1)(2)(3) . In the field of care, students witness the suffering and death of patients, they lack technical ability and knowledge for clinical practice and need to interact with the health team (1)(2)(3) . In addition, they often spend considerable time to travel to the university and/or field of study; they face financial difficulties to ensure the personal cost of living and the course itself; and need to reconcile academic life with social and family activities (1)(2)(3)(4) . These situations can be perceived as overwhelming and beyond their coping capacity and lead to neuroendocrine manifestations of stress.
This phenomenon impacts the students' health, with possible loss in academic performance (1) , increased risk of depressive symptoms (5) and Burnout Syndrome (6)(7) . Research carried out with 88 nursing students in São Paulo identified a statistically significant correlation between stress levels and the occurrence of depressive symptoms (5) . The correlation between stress and the Burnout Syndrome was demonstrated in a study involving 75 undergraduate nursing students from the United States (6) and 161 dentistry students from Switzerland (7) . In this context, it is necessary that stress factors be correctly assessed through valid and reliable instruments. The international literature has some instruments to assess stress in general populations (8)(9) , which have also been applied to university students (8)(9) .
In Brazil, the instrument for Assessment of Stress in Nursing Students (ASNS) was created in 2009 with 30 items organized in six explanatory factors (4,(10)(11) .
The ASNS aims to measure the occurrence of stress factors in different academic contexts and has already been applied in several places in the Brazilian territory.
However, the application of assessment instruments with less items has some benefits such as shorter time of application, better adherence of participants, and lower risk of filling induced by tiredness, especially when the instrument has a large number of items (12)(13) .
Short instruments also increase the explanatory power of the set of the remaining variables and enables the identification of subgroups that evaluate the same cognitive ability or capacity (factors, domains, dimensions or components) (14) . In view of these benefits and the frequent use of the ASNS in Brazil, the present study had the aim to validate a short version of the Instrument for assessment of stress in nursing students in the Brazilian reality.

Method
This is a methodological study carried out with five Brazilian higher education institutions located in different regions of the country. Students enrolled in Nursing Undergraduate Courses, from the 1st to the 8th semester, of both sexes, and aged 18 years or over were included in the study. Students not enrolled in subjects of the professional cycle who had not completed the curriculum because they had exceeded the time limit of each school, and students who were not present on the day of data collection and who were in exchange training during the period of data collection were excluded from the study. Students were approached in the classroom in previously scheduled times, as agreed with the teacher of the subject, and they were also individually located when necessary.

Results
Initially, there were 1179 nursing students enrolled in the nursing schools. However, four students were not enrolled in professional training subjects, 91 were not present on the day of collection, 3 were in exchange, 27 did not return the instruments in the expected period; three participated in the project as researchers; and four students did not agree to participate in the study. Thus, a population of 1,047 students was obtained, being: for Professional Training. These values demonstrate satisfactory reliability of the instrument.

Discussion
One of the purposes of the factor analysis is to evaluate the dimensionality of a set of indicators in order to identify the least number of factors necessary to explain the phenomenon in question (13) . In this context, the factorial analyses led to a short version of the ASNS with 19 items organized in 4 factors, whose construct validity and reliability were satisfactory for measuring stress in university nursing students.
During the analysis of the internal structure of the instrument, it was observed that the commonalities of items 2, 10 and 13 were below the established limit, and of item 29 was above this limit. The values found for concomitantly before changing the model is advisable (13) .
The observation of the other parameters altogether confirmed the construct validity of the instrument. This type of validity refers to the ability of an operational definition (construct) to truly reflect the theoretical meaning of a given concept (16) . Therefore, after obtaining the final structure, each factor of the instrument was redefined based on the items that composed it.

Thus, the factor Performance of Practical
Activities evaluates the difficulties related to the clinical environment, including performing procedures and communicating with health professionals (2) . The presence of items related to professional communication in this factor is justified by the fact that, during practical activities, students are exposed to the need to communicate with staff professionals and patients (2) .
This, in turn, involves the application of technical terms, technical-scientific knowledge and interpersonal relationship skills (11,17) , elements that can be perceived as stressors by students in view of their inexperience in the care field (18) . In this sense, communication is an element that helps to explain the stress experienced by the student during the performance of Practical Activities.
The factor Theoretical Activities encompasses items that measure students' stress caused by theoretical contributing to stress (17) . The contact with the assistance allows the student to experience challenges inherent in the nurses' performance, leading to feelings of insecurity regarding their professional training. Read each item below with attention and check with a "X" the number corresponding to the intensity of stress that the situation causes you, according to the following legend: Professional Training (Items 6, 11, 12 and 13) (Figure 2).

Conclusion
The short version of the instrument has construct validity and reliability to be applied to Brazilian nursing students at any stage of the course. This instrument has a simpler structure, which favors the adherence of participants and its use by researchers. Considering that the construct validity is strengthened as the instrument is used by researchers, it is suggested that this version be applied in future samples of nursing students so as to evaluate its psychometric properties and make eventual necessary corrections.