Impact of the COVID-19 Pandemic on the Socioeconomic Inequality of Health Behavior Among Japanese Adolescents: A 2-Year Repeated Cross-Sectional Survey.

BACKGROUND: Although disparities in socioeconomic status in health behaviors have been highlighted globally, they are not well understood in Japanese adolescents. The purpose of this study was to clarify the changes in socioeconomic disparities in adolescents' fundamental health behaviors, such as physical activity, screen time (ST), sleep, breakfast intake, and bowel movement before and during COVID-19. METHODS: This was a repeated cross-sectional study which used data from the 2019 and 2021 National Sports-Life Survey of Children and Young in Japan. Data of 766 and 725 participants in 2019 and 2021, respectively, were analyzed. Favorable health behaviors were defined as daily moderate to vigorous physical activity (MVPA) of at least 60 minutes, ST of less than 2 hours, sleep of 8 to 10 hours, daily breakfast intake, and bowel movement frequency of at least once in every 3 days. We calculated the slope index of inequality and relative index of inequality in each health behavior for equivalent household income levels for assessing absolute and relative economic inequalities. RESULTS: Compliance with MVPA and ST recommendation significantly declined from 20.1% and 23.0% in 2019 to 11.7% and 14.9% in 2021, respectively. The slope index of inequality and relative index of inequality increased in MVPA for income levels, but decreased in daily breakfast in 2019 to 2021. Although the widening and narrowing of the disparity were inconclusive for ST, it exacerbated for the higher-income groups. CONCLUSIONS: Our study revealed widening of economic disparities in the achievement of recommended MVPA and narrowing of it in breakfast intake among adolescents before and during COVID-19.

Time trends of socioeconomic inequalities in adolescent smoking in Okinawa, Japan, 2008-2016: a repeated cross-sectional study.

BACKGROUND: Smoking among Japanese adolescents has decreased noticeably. However, little is known whether the decreasing trend in adolescent smoking can be seen across all socioeconomic status (SES) groups. This study aimed to examine trends in socioeconomic inequalities in smoking among Japanese adolescents between 2008 and 2016. METHODS: We conducted a repeated cross-sectional study using data from three surveys of high school students in Okinawa, Japan, in 2008, 2012, and 2016. The study participants consisted of 7902 students in grades 10 through 12 (15-18 years). Smoking was assessed as current cigarette use. SES indicators included familial SES (parental education and family structure) and student's own SES (school type). To evaluate absolute and relative inequalities, prevalence differences (PDs) and ratios (PRs) between low and high SES groups were estimated. The slope index of inequality (SII) and relative index of inequality (RII) were also calculated. RESULTS: Smoking prevalence among boys and girls significantly declined from 11.5% and 6.2% in 2008 to 4.7% and 1.9% in 2016, respectively. Similar decreasing trends in smoking were found among most of the SES groups. The PDs and SII for parental education in boys and family structure in girls decreased over time while those for school type persisted among boys and girls. The PRs and RII for school type in boys increased while those for other SES indicators among both sexes remained stable over time. CONCLUSIONS: Smoking among Japanese adolescents has been declining and time trends of socioeconomic inequalities in smoking varied by absolute and relative measures. Further policies and/or interventions to reduce smoking inequalities should focus on the context of schools, especially in vocational high schools.

Validation of the Physical Activity Questions in the World Health Organization Health Behavior in School-Aged Children Survey Using Accelerometer Data in Japanese Children and Adolescents.

BACKGROUND: An international physical activity (PA) questionnaire is beneficial to make cross-country comparisons among children and adolescents. This study assesses the validity of the PA questions in the World Health Organization Health Behavior in School-Aged Children (WHO HBSC) survey in Japanese children and adolescents. METHODS: Participants were fifth- to sixth-grade Japanese primary school students (67 students aged 10.8 [0.5] y) and first- to third-grade junior high school students (108 students aged 13.0 [0.7] y). The Japanese version of the PA questions in the WHO HBSC (WHO HBSC-J) was used. To assess the validity of the PA questions, the authors used a partial correlation adjusted for sex, age, and relative weight between the answers to the survey questions and objectively measured moderate to vigorous PA (MVPA) by an accelerometer. RESULTS: A significant positive correlation was found between accelerometer-measured MVPA and the number of reported days with at least 60 minutes/day of MVPA in primary school students (r = .39, P = .002) and junior high school students (r = .32, P < .001). CONCLUSION: The HBSC-J has moderate validity for evaluating MVPA in Japanese primary school and junior high school students.

The Relative Association of Collective Efficacy in School and Neighborhood Contexts With Adolescent Alcohol Use.

BACKGROUND: It is unclear whether either neighborhood collective efficacy or school collective efficacy is associated with adolescent alcohol use. This study aimed to examine the relative contributions of collective efficacy, both in school and in the neighborhood contexts, to alcohol use among Japanese adolescents. METHODS: A cross-sectional study was conducted in public high schools across Okinawa and Ibaraki Prefectures in Japan in 2016. The study participants consisted of 3,291 students in grades 10 through 12 cross-nested in 51 schools and 107 neighborhoods. Alcohol use was measured as current alcohol drinking, which was defined as self-reported drinking on at least 1 day in the past 30 days. Collective efficacy was measured using scales of social cohesion and informal social control in school and the neighborhood. Contextual-level collective efficacy was measured using aggregated school-level and neighborhood-level individual responses, respectively. We used non-hierarchical multilevel models to fit the cross-nested data. RESULTS: Significant variation in alcohol use was shown between schools but not between neighborhoods. After adjusting for covariates, school collective efficacy at individual- and contextual-levels was protectively associated with alcohol drinking (odds ratio [OR] for the increase of one standard deviation from the mean 0.72; 95% confidence interval [CI], 0.63-0.82 and OR 0.61; 95% CI, 0.49-0.75, respectively), whereas neighborhood collective efficacy at individual- and contextual-levels was not associated with alcohol consumption. CONCLUSION: The school-level associations of collective efficacy with adolescent alcohol use may have the greater impact than the neighborhood-level associations. Adolescent drinking prevention efforts should include enhancing school collective efficacy.

Mediating effect of aerobic fitness on the association between physical activity and academic achievement among adolescents: A cross-sectional study in Okinawa, Japan.

The purpose of this study was to examine the potential role of aerobic fitness (AF) as a mediator of the association between physical activity (PA) and academic achievement (AA) among Japanese junior high school students. A cross-sectional data was collected from 608 7th grade students enrolled at five public junior high schools in two suburban municipalities in Okinawa, Japan. Self-reported PA was assessed using the Patient-Centred Assessment and Counselling for Exercise plus Nutrition questionnaire. The 20-meter shuttle run test was performed to determine AF. AA was evaluated using the overall grade point average. Family structure, parental education level, and achievement motives were the self-reported covariates. The results of the bootstrapped mediation analysis indicated that PA had a direct effect on AF, which in turn influenced the AA among boys. After adjusting for AF, the association between PA and AA disappeared while the association of AF with AA still remained. However, neither PA nor AF was associated with the AA of girls. Therefore, the hypothesis that AF might mediate the relationship between PA and AA was supported for boys. Promoting AF, as a result of engaging to PA could positively influence AA particularly in boys.

Does Physical Fitness Affect Academic Achievement among Japanese Adolescents? A Hybrid Approach for Decomposing Within-Person and Between-Persons Effects.

Positive association between physical fitness and academic achievement in adolescents has been suggested yet the causal effect of physical fitness on academic achievement remains unclear. This study examined if longitudinal changes in physical fitness were associated with changes in academic achievement among junior high school students. Analyses were based on a two-year with three time-point data of 567 students (aged 12⁻13 years old at the baseline-point; 303 boys) who entered in five Japanese junior high schools in 2015. Academic achievement was evaluated using the student's overall grade point average. Comprehensive physical fitness score was summed up from eight fitness tests: 50-m sprint, standing broad jump, repeated side-steps, sit and reach, sit-ups, hand-grip strength, handball throw, and 20-m shuttle run or endurance run. The hybrid regression model was applied to examine the impact of change in physical fitness on change in academic achievement using multiple imputation to account for non-response at follow-up. The changes in fitness score within-person and the differences in average of fitness score of three-time points between-person were associated with change in overall grade point average for boys. No significant association between fitness score and overall grade point average was observed in girls. Opportunities for increased physical fitness may be important to support academic achievement, particularly in junior high school boys.