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.

Impact of thirteen-valent pneumococcal conjugate vaccine on nasopharyngeal carriage in healthy children under 24 months in Okinawa, Japan.

In November 2013, a 13-valent pneumococcal conjugate vaccine (PCV13) for all infants aged younger than 5 years was incorporated into the Japan national immunization program. An annual survey of nasopharyngeal carriage rates was performed on healthy infants aged 2-24 months from Okinawa, Japan to evaluate the effect of PCV13 on pneumococcal colonization. Of 756 evaluable infants, 203 pneumococcal strains were detected in 193 infants. The overall nasopharyngeal carriage rate was 25.5%, which was not different from our previously reported isolation rate before the introduction of PCV13. The main serotypes of the Streptococcus pneumoniae strains are 15A (18.2%), non-typeable (14.8%), and 15B (11.8%). The carriage rates of pneumococcal strains with 7-valent pneumococcal conjugate vaccine serotypes and PCV13 serotypes were 3.0% and 9.9%, respectively. These values were significantly lower than we reported before the introduction of PCV13. However, the carriage rates of non-PCV13 serotypes have increased. Multivariate logistic regression analysis suggested that siblings and day care attendance are risk factors for pneumococcal carriage.

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.

Unnecessary Dieting Intention and Behavior among Female Students in Naha City, Japan.

Weight concerns and dieting are prevalent among female adolescents both in Western and Asian countries. They can result in negative psychological and physiological consequences. This study aimed to examine the relative importance of social and personal factors in the decision to diet among female adolescent students in Japan, applying the Theory of Planned Behavior. Data were collected from five junior high schools and three high schools in Naha City, Okinawa Prefecture, in 2010, through self-administered questionnaires. The data of 756 female students were assessed. The independent variables included social factor variables (norms) and personal factor variables (attitude to dieting, perceived behavior control, body esteem, body-figure discrepancy and past dieting). The dependent variables were dieting intention and behavior. Hierarchical multiple regression analyses were performed to examine three models: model 1 (age and obesity index), model 2 (social factor variables with age and obesity index) and model 3 (all variables). Although model 2 failed to explain a substantial proportion of the variance, model 3 explained approximately a half of the variance for intention (R(2) = 0.507) and more than one third of the variance for behavior (R(2) = 0.376). Past experience of dieting was the best predictor of both dieting intention and behavior. Body esteem was the second best predictor for dieting behavior. In conclusion, personal factors are more likely than social factors to drive the dieting decision. Diet education programs should consider targeting frequent dieters and those with poor body esteem.