Musculoskeletal disorders among healthcare providers are being studied in many countries. In Italy, numerous complaints about these disorders have been reported by workers in various healthcare professions. These disorders are also considered serious health problems among physiotherapists and radiologists [1]. Among the healthcare professionals, nurses are the largest group with musculoskeletal disorders.

A study in England showed that the frequency of low back pain among nurses was equal to that of industrial workers. Accordingly, 85.7% of the subjects in the study suffered from low back pain one year after entering the nursing profession [2]. Overall, 90.3% of nurses working in South Korean hospitals had back pain at least once a month [3]. Furthermore, the prevalence of low back pain is about 62% among Italian nurses [4], and 80.9% among nurses in Hong Kong [5]. Among Iranian nurses, more than half suffer from low back pain [456].

Previous studies have shown that the risk of low back pain increases rapidly with greater amount of physical work and psychological stress [378]. The pain frequently experienced by nurses undermines psychological health and reduces professional performance. Evidence has shown that low back pain is the most important reason for the nurses to change jobs [9].

Nurses, because of the nature of their profession, face adverse job related factors such as worksite stress and unhealthy physical and social behaviors leading to musculoskeletal disorders. Therefore, enhancing healthy behaviors among nurses based on a biopsychological social factors is essential [10]. Improvement in personnel skills, creation of a supportive environment and more effective macro policy-making could lead to many positive changes that might enhance the well-being and quality of the workplace for many health professionals worldwide [1011].

Social cognition is one of the important cognitive concepts studied in recent decades, and is closely related to the subject of human issues, understanding people and their behavior. This kind of cognition is reflexive and participatory and involves conciliatory actions [1213]. Social cognition emphasizes that behavior is affected by learning, which is in turn influenced by societal models. Consequently, modifying environmental conditions with ensuring efficient self-care and improving inter-personnel relationships are among the most important methods to enhance health [10].

The social cognitive theory (SCT) of Bandura, formerly known as the social learning theory, has attracted the attention of health educators because it deals with the explanation and prediction of behaviors through the interactions between the individual, the behavior and the environment. Therefore, because of the nature of the nursing profession and behavior related to low back pain, the work environmental factors and individual psychological determinants are the obvious influences. The researchers are unaware of any measuring instruments based on SCT that are available for Iranian nurses. The aim of this study was to develop a theory-based instrument for measuring the relevant factors associated with low back pain; as such, the application of this instrument may help in addressing the prevalence of low back pain for the nurses.

This was a cross sectional study that employed mixed methodology. Interviews with key experts were conducted to review the existing measurement instruments, to consider factors thought to be important in reducing pain, to gauge the ability of nurses, and to address factors leading to risky behaviors which may contribute to low back pain. These components were compared with concepts of SCT to design the questionnaire items. The research team experts also guided further refinement of the questionnaire. Similar statements were either removed from the questionnaire or merged; the questionnaire items were made simple and clear so that each one measured only one variable.

In order to determine the formal validity, this instrument was distributed among 10 nurses and the impact score was calculated at 3.3. To determine the content validity, we used both qualitative and quantitative methods. An expert panel consisting of 15 specialists composed of neurosurgeons, rheumatologists, epidemiologists, nursing instructors, health educators and experts in qualitative methods evaluated the questionnaire for 'grammar', 'wording', 'item allocation', and 'scaling' indices [1415]. The expert panel checked all items and provided their modifications for the questionnaire.

The content validity ratio (CVR) and the content validity index (CVI) were used to calculate quantitative content validity. Items were assessed using a 3-point rating scale: (1) essential, (2) useful, but not essential, and (3) unessential [1617]. Based on Lawshe's table, items with CVR value of 0.4 or above were considered acceptable [18]. For CVI, according to Waltz & Bausell's recommendation, the same experts were asked to evaluate the items based on a 4-point Likert scale on (1) simplicity, (2) relevancy, and (3) clarity [1920]. The CVI value of 0.79 or above was considered satisfactory for each statement [21].

The construct validity of the instrument concepts was determined by a sampling of 500 nurses. This sample consisted of nurses who had the entry and exit characteristics of the study. Ten nurses were selected from a different ward for individual questionnaire items. The two-section questionnaire, consisting of 17 demographic questions and 50 questions based on SCT was completed by the nurses. The demographic questions dealt with socioeconomic characteristics, employment/working status, low back pain characteristics, and healthy preventive behaviors due to back pain.

A total of 500 nursing staff including 332 females (66.4%) participated in the study. The mean age of participants was 37.71 (standard deviation [SD]=6.75) years, and the mean work experience was 10.77 years (SD=9.45). A total of 20 nurses including 14 females (70%) with mean age of 36.75 (SD=7.96) years took part in the test-retest sample. The mean work experience of this sample was 9.45 years (SD=5.82). The demographic characteristics of the participants are shown in the Table 1.

This study reports the development and psychometric evaluation of nursing low back pain predictor questionnaire for Iranian nurses. The findings revealed satisfactory psychometric properties for the instrument with 6 factors and 46 items. Since chronic low back pain in Iran is a prevalent health problem among nurses, the development of a multi-dimensional questionnaire, which deals with low back pain from sociological, physical and psychological aspects has been given special attention.

The statements for this instrument were prepared through literature review based on SCT and biopsychosocial characteristics for low back pain among the nursing professionals. It has been revealed that individuals, who experienced a problem, are the best ones to provide input on factors, which might be effective [14]. In our study, we asked the nurses about the related factors, which might influence their low back pain in the framework of SCT.

In the present study, explanatory factor analysis showed that the factor of observational learning had satisfactory loading. This result indicated that Iranian nurses believed that they could learn healthy behaviors related to back pain through observation. Previous study indicated that observational learning may contribute to development and maintenance of pain-related beliefs that consequently resulted in healthy behaviors [25].

The other factor that was verified in this study was outcome expectation. This factor refers to anticipation of the probable outcomes that ensue as a result of engaging in a specific behavior [26]. Previous evidence identified three types of outcomes including physical outcomes, which include positive and negative consequences of the behavior, the outcome of social approval or disapproval of engaging or disengaging in a given behavior, and positive and negative self-evaluation that encourages individuals to participate in a specific behavior [26]. In the present study, we discussed these outcomes with the participants and asked if they would engage in preventive low back pain behaviors at the working site.

In SCT, there were two separate concepts of outcome expectation and outcome expectancies that refer to beliefs regarding the likelihood of various outcomes resulting from the behaviors, and the value of the outcomes, respectively [2627]. In present study, both concepts were grouped into one category and named "outcome expectation." McAlister et al. [27] believed that an individual's value and an individual's expectation are subjective items and can be categorized into the same category as a key concept named psychological determinants of behavior. In the present study, EFA grouped the questions regarding self-efficacy, referring to beliefs about nurses' ability to perform a desired behavior in their working environment [27] and the questions regarding situational perception, referring to how nurses perceive and interpret the environment around them [26], into the same category named "self efficacy." The relationship between social environmental factors such as social support and self-efficacy has been confirmed [28].

A factor that gained satisfactory loading was self-efficacy in overcoming impediments. This factor describes the confidences that a person has in overcoming barriers while performing a given behavior. Sharma believed that using persuasion and reinforcement in overcoming work barriers in work centers promotes self-efficacy [27]. Another factor derived from explanatory factor analysis is self-regulation or goal setting and developing plans to accomplish a chosen behavior. This study grouped the questions related to two concepts of self-regulation and environment grouped into one category named "self-regulation." Self-regulation is a key concept of SCT that refers to skills individuals use to manage their behaviors. This finding is similar to that of McAlister et al., who stated that individuals control their behaviors through rewards and planning and organization of environmental changes. Self-regulation is one of the key constructs of SCT [28] and it was explored in the present study. Emotional coping concept, which is a group of techniques employed by the person to control the emotional and physiological states associated with acquisition of a new behavior, is another factor that obtained satisfactory loading in this study.

In this study the nine concepts of SCT were grouped to six factors. McAlister and co-workers verified that the nine concepts of SCT could also be grouped into the five categories of psychological determinants, observational learning, environmental factors, self-regulation, and moral disengagement [28].

Although this study had several strengths, there were some limitations. The most important limitation was that the nurses answered the questions while they were at their worksite, so their stress and anxiety at their working setting could have affected their answers. The other limitation might be that only 20 individuals undertook the test-retest analysis, which is quite small. Although this number was selected based on existing evidence [24], a larger sample could have had more reliability. Despite these limitations, this instrument had the optimal statistical properties regarding predictors for low back pain among the Iranian nursing staff.

The developed Questionnaire is a reliable and validated theory-based instrument, which can be used to predict the factors of work related to low back pain among nurses. However, with the existing tools, more research should be done to demonstrate the eligibility and consistency of this instrument within the different target groups.