[The association between lifestyle and body proportion in primary school children].

OBJECTIVES: To investigate the association between lifestyle and body proportion in children. METHODS: The subjects were 499 students at "B" primary school, located in "A" prefecture. Data were obtained by analyzing the results of routine health checkups carried out in the fiscal year 2007 by using self-reported questionnaires on lifestyle. For the analysis of body proportion, the degree of obesity (overweight degree) divided by sex, age, and body height was calculated using a standard weight-based criterion; values greater than +20% indicated an inclination toward obesity, and values smaller than -20% indicated a tendency toward underweight. To analyze the relation between body proportion and lifestyle, binomial logistic regression analysis was performed using body proportion ("normal group" and "obesity inclination/underweight group") as the dependent variable and lifestyle as the independent variable. In addition, lifestyle factors common to and unrelated to both the obesity-inclined and the underweight groups were examined. RESULTS: Comparison between the incidences of children with an inclination toward either obesity or underweight with national averages in the same fiscal year revealed that the overall inclination toward obesity was high in boys. Among other factors, influence by lifestyle habits such as insufficient chewing and the habit of watching TV for long periods was suggested. The incidence of children tending toward underweight or obesity was high among boys in the fourth and fifth grades and in girls in the fifth grade. Logistic regression analysis showed that the occurrence of unhealthy lifestyle habits such as "insufficient chewing" (2.1 times the number of those who chew well; P = 0.016) and "TV watching for more than 2 hours per day" (1.9 times the number of those who do not watch TV for more than 2 hours per day; P = 0.071) were highly correlated with the incidence of underweight or obesity. In addition, when we categorized the relationship between lifestyle and body proportion into 3 types ("tendency to underweight", "normal," and "obesity inclination"), we found a high incidence of the unhealthy lifestyle factor "insufficient chewing" in the groups that tended toward underweight or obesity and "TV watching for more than 2 hours per day" in the group that was inclined toward obesity. CONCLUSION: When considering lifestyle issues, children inclined toward being either obese or underweight are often perceived to be contradictory to their external appearance. However, the results of the present study suggest that children with a tendency to be underweight and those with an inclination toward obesity share several lifestyle habits such as insufficient chewing.

Analysis of risk factors for dental caries in infants: a comparison between urban and rural areas.

OBJECTIVES: This study investigated the incidence of caries in infants and explored the risk factors related to noteworthy variations between urban and rural areas. METHODS: Subjects were 232 infants (111 males and 121 females) aged 1.6 and 3 years born in "N" town between the fiscal years of 1997 and 2001. Infants aged 1.6 and 3 years had 99.6 and 100% participation in health checkups, respectively. Of the total, 148 and 84 infants were living in the urban and rural areas, respectively, of "N" town. RESULTS: Caries incidence and the average number of carious teeth (decayed/missing/filled teeth, dmft) for infants aged 1.6 years were significantly higher in the rural area than in the urban area, indicating that environmental factors that predispose infants to develop dental caries exist in the rural area. In addition, logistic regression analysis for infants in each of the two areas revealed that risk factors of the child-care environment, for example living with grandparents and brushing by parents, stood in marked contrast with each other. Moreover, the odds ratio of the risk factor dozing off while drinking showed a marked difference between the areas, although this risk factor was common in both areas. CONCLUSIONS: The results of this study indicated that several factors of the child-care environment, for example the daytime caring person, are related with caries development. Scientific elucidation of the risk factors that give rise to high prevalence of caries in specific regions and access to the whole picture of the disease mechanism may have great potential to lead to the development of effective countermeasures and to contribute to the reduction of dental caries in preschool children.

Comparability of epidemiological information between self- and interviewer-administered questionnaires.

The aim of the present study was to determine the extent to which respondents provided the same answers to a health-related lifestyle questionnaire in self- and interviewer-administered forms. A total of 234 subjects completed a 110-item questionnaire in both interviewer and self-administered forms. Modes of administration were separated by a 2-week interval. The order was determined by random allocation. The presence and the extent of the tendency to give socially acceptable responses were evaluated using percentage of bias calculated as the ratio of the difference in proportion of positive responses or the mean between interviews and questionnaires and those in questionnaires. All percentages of bias were in the positive direction, ranging from 1.4% (physical exercise) to 26.1% (general life stress). The average percentage of bias was higher in women than in men and were stronger for younger respondents. The age differences between interviewer and respondent were inversely and most strongly related to percentage of bias. Self- and interviewer-administered questionnaires yield very similar results in discriminating between subjects, but the interviewer-administered questionnaire showed systematically more desirable responses to questions related to lifestyle factors. The differences in characteristics between interviewer and respondent may be important determinants of the socially desirability bias in the interview.