The effect of peer education based on adolescent health education on the resilience of children and adolescents: A cluster randomized controlled trial

principles of assignment are as follows: positive entries have 5 options: totally inconsistent (1 point), comparatively inconsistent (2 points), unclear (3 points), comparatively consistent (4 points), and fully consistent (5 points). Some items were reverse scored: totally inconsistent (5 points), comparatively inconsistent (4 points), unclear (3 points), comparatively consistent (2 points), and fully consistent (1 point). The total score ranged from 27 to 135, with a higher score indicating a higher level of psychological resilience. We tested the reliability of this scale in our research sample, with the resultant Cronbach’s alpha of target focus, emotional control, positive cognition, family support, interpersonal assistance, and the overall scale being 0.765, 0.648, 0.709, 0.590, 0.666 and 0.818, respectively. According to the influencing factors of resilience [49, 50], following sociodemographic characteristics were collected through self-designed questionnaires: age (continuous variable); participants’ education level (primary school/middle school); sex (male/female); whether the individual is an only child (Yes/No); relationship between parents and with parents (dishar- monious/moderate/harmonious) linked to the number of conflicts; parents’ education level (junior high school or lower/senior high school and technical secondary school/college or higher); family economic status (good/moderate/bad); academic achievements (good/moder- ate/bad); the number of close friends (�2/3-5/�6); and parenting style (democratic/auto- cratic/doting/disregardful). Quality assurance

In the design of the study, experts in epidemiology, statistics, child and adolescent health, psy- chology and pedagogy were consulted extensively, and the plan was formulated in combina- tion with the discussion of the research group. Before the investigation, all investigators received uniform standardized training to ensure the quality of the investigation. During the investigation, with the cooperation of the school leaders, the investigator explained the matters needing attention to fill in the questionnaire to the research subjects and guided the students to complete the questionnaire. The questionnaires were collected and checked by the members of the research group, and the questionnaires with obvious logical errors and missing items were returned to the students for revision in time. After the survey, all survey data were recorded and checked by two groups of investigators using EpiData 3.1 software. The subse- quent processing of outliers and statistical analysis of the data were supervised by epidemiolo- gists and statistical experts. Data analysis EpiData 3.1 was used for data collection and collation, SAS 9.4 and SPSS24.0 were used for sta- tistical analysis. The quantitative data were expressed by mean and standard deviation, and the qualitative data were expressed by number of cases and percentage. Propensity Score Matching (PSM) was used for data matching if baseline information differed significantly between the intervention and control groups. T test and one-way ANOVA were used for the difference

between groups of continuous variables with normal distribution, and rank sum test was used for the difference between groups of continuous variables with non-normal distribution. Chi- square test or Fisher’s exact test was used for differences between groups of categorical vari- ables. A linear mixed model was used to compare the change of resilience score between the two groups after intervention, and the cluster effect value ICC was calculated. After determin- ing the changes between baseline and final follow-up, the effectiveness of peer education inter- vention on adolescent resilience was tested using a generalized linear mixed model (GLMM), with the change value of resilience score as the dependent variable and the intervention style PLOS ONE The effect of peer education based on adolescent health education on resilience of children and adolescents PLOS ONE | https://doi.org/10.1371/journal.pone.0263012 February 2, 2022 7 / 18