Low health literacy and psychological symptoms potentially increase the risks of non-suicidal self-injury in Chinese middle school students

Convenient cluster sampling was conducted from junior and senior high schools located in 6 cities in China, including both urban and rural regions, as follows: Shenyang (Liaoning Province), Xinxiang (He’nan Province), Guangzhou (South central Guangdong Province), Chongqing (one of China’s four direct-controlled municipalities), Xinjiang (Xinjiang Uyghur Autonomous Region) and Yangjiang (Southwest of Guangdong Province). Eight schools in each city were selected including two junior schools and two senior schools from rural regions and two junior schools and two senior schools from urban regions. This study was conducted from December 2013 to May 2014.

A total of 27044 students (Aged 11–19 years) were recruited in this study, participants were from grade 7–12 in junior and senior high schools. In the participating schools, 774 of the 27044 sampled students were excluded from the study because of their absence from school on the day of the survey or reluctance to respond to the questionnaires. We finally received 26152 (96.7 %) questionnaires, in which 25378 (97.0 %) were valid (missing data > 5 % was discard). In addition, the participants of six cities were 3389 (Shenyang), 3375 (Xinxiang), 2904 (Guangzhou), 6394 (Chongqing), 3179 (Xinjiang), and 6137 (Yangjiang), respectively.

Approval for the study was granted by the Ethics Committee of Anhui Medical University (Mar. 1, 2014; approval number 20140087). Permission for the study was requested from schools, parents, and students before completion of the surveys. During the organization period, we had signed informed consent with each participating school. The students were allowed to participate in the study upon receiving completed consent form from their parents. One week prior to screening day, the parents were informed of the study through a notice sent home from the schools asking them to contact the teachers by phone if they wish their child to participate in the survey. Prior to the formal investigation, the team members introduced the aims and procedures of the study to the students, and provided an opportunity for them to ask questions. If they were not willing to participate, they were allowed to withdraw from the study. Consent to participate in the study was recorded in a separate consent form with the questionnaire, and it was confirmed upon completion and return of the questionnaire.

A self-report questionnaire was used to collect information on socio-demographic variables, HL, psychological symptoms, and NSSI during a 20–30 min session in the classroom. The following socio-demographic characteristics were obtained: age, gender, grade (junior or senior high schools), residential background (urban or rural area), household structure (only-child or more than one child), parents’ educational level, and self-reported family economy.

HL was assessed with a reliable questionnaire: the Chinese Adolescent Interactive Health Literacy Questionnaire (CAIHLQ), and the reliability and validity of CAIHLQ have been demonstrated in previous study [18]. It consists of 31 questions grouped into 6 domains, including 6 questions assessing physical activities (e.g. ‘Follow a planned exercise program.’), 5 for interpersonal relationship (e.g. ‘Take times with your family or friends.’), 6 for stress management (e.g. ‘Balance time between study and play.’), 4 for self- actualization (e.g. ‘Feel each day is very meaningful.’), 5 for health awareness (e.g. ‘Containing sugars and food continuing sugar.’), and 5 for dietary behavior (e.g. ‘Eat 200–400 g of fresh fruit each day.’). All of these questions have five answer categories (never and no desire, never but with desire, occasionally and irregularly, often, and routinely), and the total score is standard converted to a score that ranges from 31 to 155, with lower scores indicating inadequate HL (see Additional file 1). Variance cumulative contribution rate was 63.847 %; internal consistency test showed that the total questionnaire Cronbach’s α was 0.937, Cronbach’s α of each dimension was 0.752 to 0.898; correlation analysis showed that Pearson correlation coefficients of each item and the total score were all above 0.4, and the Pearson correlation coefficient of each item and its dimension were more than 0.5, all the indicators were at the significant level and had a good reliability and validity. Students in this study were categorized as low, medium and high HL when their scores were < P_25, P ₂₅ - P ₇₅ and > P ₇₅ respectively.

Psychological symptoms were measured using the psychological domain of the Multidimensional Sub-health Questionnaire of Adolescents (MSQA) [19], which consists of 39 items in 3 subscales: 17 questions for emotional symptoms (e.g. ‘Do you always feel nervous?’); 9 for conduct symptoms (e.g. ‘Do you always have the impulse to damage something?’); and 13 for social adaptation symptoms (e.g. ‘Could you always not be suited for school life?’). Each participant was asked to rate each item according to a 6-point scale where ≥ 3 months, ≥ 2 months, ≥ 1 month, ≥ 2 weeks, ≥ 1 weeks, and none or < 1 week. In calculation step, the symptom duration time lasting ≥ 1 month, lasting ≥ 2 months, or lasting ≥ 3 months was assigned renewedly to 1 and the others to 0. In accordance with the national norm established for MSQA of adolescents in China [20], the 90th percentile of national norm in total score and six subscales scores were selected as the cut-off points, which was eight for psychological problems in this study. Therefore, the number of score ‘1’ ≥ 8 was supposed to have psychological symptoms. The MSQA has been reported by various groups to be a valid and reliable method to explore determinants and the current state of adolescents’ psychological health status [21‐24].

NSSI was elicited in a self-report by answering: Have you ever harmed yourself in a way that was deliberate, but not intended as a means to take your life in the past 12 months? The response options were “yes or no” [8, 25]. Eight NSSI behaviors were presented, and the details of the questions were as follows: (1) Have you ever hit yourself?; (2) Have you ever pulled your hair yourself?; (3) Have you ever banged your head or fist against something?; (4) Have you ever pinched or scratched yourself?; (5) Have you ever bitten yourself?; (6) Have you ever cut or pierced yourself?; (7) Have you ever exposed yourself to smoke, fire, and flames or come in contact with heat and hot substances?; and (8) Have you ever ingested a toxic substance or object? All students who answered yes (one or more times) were judged as having NSSI behaviors. In the previous study, Cronbach’s alpha coefficient for the NSSI was reported to be 0.776 [7].