In this study, we aimed to assess the effectiveness of a school-based home-collaborative lifestyle education program for adolescents (PADOK) in reducing poor subjective psychosomatic symptoms (SPS). The study was designed as a two-armed parallel cluster randomised controlled trial and the study population comprised adolescent students (aged 12-14 years, n = 1,565) who were recruited from 19 middle schools in Japan. The PADOK intervention or usual school programme was provided in schools to all eligible participants. The primary outcome was the SPS score at 6 months, while secondary outcomes included lifestyle factors, BMI, and dietary intakes. Analyses were undertaken on an intention to treat (ITT) basis accounting for the clustered design. Nineteen schools were randomised to the PADOK group (10 schools) and control group (9 schools). The numbers of students used for analysis were 1,509 for ITT and 1,420 (94.1%) for PPS. At 6 months, the crude mean change from baseline of the SPS scores by ITT analysis showed a significantly greater reduction in the PADOK group compared to that in the control group (-0.95, 95% CI -1.70 to -0.20, P = 0.016), while those for baseline-adjusted and multivariate-adjusted values showed similar directionality but were not significant (P = 0.063 and P = 0.130). The results indicated that the PADOK program may improve poor SPS scores among adolescents.
