School-based lifestyle education involving parents for reducing subjective psychosomatic symptoms in Japanese adolescents: study protocol for a cluster randomised controlled trial

INTRODUCTION: Severe subjective psychosomatic symptoms (SPS) in adolescents are a major public health concern, and lifestyle modification interventions for reducing SPS are important topics. Recently, we developed a school-based lifestyle education involving parents for reducing SPS of adolescents (SPRAT), an improved version of the programme from our previous study Programme for adolescent of lifestyle education in Kumamoto (PADOK). This study aimed to evaluate the effectiveness of SPRAT in reducing SPS among adolescents. METHODS AND ANALYSIS: This is a 6-month, cluster randomised clinical trial with two intervention arms (SPRAT vs usual school education). The study population will be composed of middle school students (aged 12–14 years) with their parents/guardians in Japan. SPRAT is expected to be a more powerful programme than PADOK as it reinforces the role of parent participation. The primary endpoint will be the change from baseline SPS scores to those obtained after 6 months. Between-group differences will be analysed following the intention-to-treat principle. Crude and multivariate adjusted effects will be examined using a general linear mixed-effects model for continuous variables and a logistic regression model for dichotomous variables. The sample size required was determined based on the information needed to detect a difference in the primary outcome with a significance level of 5% and power of 80% under the assumptions of 40 students per cluster (assuming the same sample size for each cluster), an effect size of 0.3 and an intraclass correlation coefficient of 0.02. In total, participation by 28 schools (14 schools in each arm) (students: n=1120) will be needed. ETHICS AND DISSEMINATION: This study was approved by the Medical Ethical Committee of Minami Kyushu University in 2017 (number 137). The findings will be disseminated widely through peer-reviewed publications and conference presentations. TRIAL REGISTRATION NUMBER: UMIN000026715; Pre-results.