Design
This study used a cross-sectional design among 5th-grade students attending elementary schools in Tehran, Iran from October 2018 to March 2019. The independent variables were the constructs of the SCT (self-efficacy, knowledge, skills, and outcome expectation beliefs). The dependent variable was the back behavior (Fig.1).
The study sample
The study sample was consisted of female students aged 11 years. They were selected from two (out of 8) randomly selected elementary schools in North-West of Tehran, Iran. The district has a population of variety socio-economic background. In order to explore the predictive factor, the study of Dullien article [1] was referred to determine the required sample size. According to Dullien to conduct a study with power of 80%, and standard deviation of 14.5 for performance score with a minimum precision of 2 at 5% significance level, a sample of 202 pupils would be required. However, since in school-based studied, selection almost is impossible, thus the whole classes were selected and 204 fifth grade students were recruited. We obtained permission from school principals and all parents completed written informed consent.
Measures
- Information on pupils’ parents job and level of education and a question about the presence of back pain during last week among pupils (Yes, No).
- To measure main independent variables the Cardon et al. questionnaire was used [20]. The questionnaire contained 43 items including the following sections:
(i). Back care knowledge consisting of 10 multiple-choice items on general back care knowledge. For each item respondents could choose a correct answer from a list of statements. The correct answers received 1 point and if they have responded wrongly they get zero score for that item. The score on this construct ranged from zero to 10 where the higher scores indicated higher knowledge.
(ii). Back care skills, which contained a checklist for practical assessment of skills, for back care principles. The checklist consisted of 23 items tapping into seven tasks (sitting at a table; picking up the crate; carry the crate; set the crate down on the table; pick up a pencil; move the crate; and book bag use). Each item is rated on a 5-point scale ranging from 1 (very poor) to 5 (excellent) giving score ranging from 23 to 115 where higher scores indicated better fulfillment of tasks.
(iii). Self-efficacy contained 4 questions asking that how easy or difficult the following were: participation in daily physical activity and sports, attaining a natural curvature of the spine, minimal loading of the book bag and paying attention to ergonomical postures. Each item is rated on a five-point scale (from difficult to easy) giving score ranging from 4 to 20 where the higher scores indicated higher self-efficacy.
(iv). Outcome expectation beliefs (behavioral beliefs) contained 6 items asking whether sitting, swimming, running, participating in physical education, cycling and lifting heavy objects are ‘dangerous’ when having a backache. Each item is rated on a five-point scale (strongly disagree to strongly agree) giving score ranging from 6 to 30 where higher score indicated stronger beliefs.
3. Back care behavior as outcome measure contained six questions regarding daily activities on checking weight of the book bag; carrying the bag with 2 straps; knee position when putting on shoes; doing exercises every day; and postural behavior while lifting and carrying objects. Each question is rated on a five-point scale (never = 1 to ever = 5) giving a score ranging from 6 to 30 where higher scores indicated better preventive behavior.
Data collection
Before data collection, we explained the aim of this study to the principal, class teacher, and pupils of the two schools. After indicating the permission from them, we distributed the questionnaire. There were two independent research assistants to help in this study, and rated students’ skills based on checklist. Since the analysis of the relationship between the variables is worthy of attention, in fact, we are looking to identify that the relationships between variables that are extracted from the theory are confirmed by the data collected from the sample.
Data analysis
Descriptive statistics were used to explore the data. In addition, we used stepwise multiple regression analysis in order to assess the relationship between back care behavior (outcome variable) and independent variables including knowledge, skills, SE and expectation beliefs. The level of significance was set at p <.05. The data were analyzed using the SPSS V24 software to test the correlation between study variables.