Gender differences in self-harm and drinking behaviors among high school students in Beijing, China.

BACKGROUND: Self-harm and drinking are both serious problems in adolescents and many studies presented evidence of their association. However, gender differences in this association are seldom deeply discussed. Our study aimed to evaluate the prevalence of self-harm and explore its association with drinking behaviors by gender and investigate the extent to which the gender differences exist in the association between self-harm and drinking. METHODS: A total of 32,362 students in grades 7 to 12 in Beijing, China were anonymously surveyed and included in our study using two-stage, stratified probability proportion sampling. Self-harm, drinking behaviors and other basic information were obtained from an anonymous questionnaire. Demographic variables, self-harm and drinking behaviors were analyzed using the Chi-square test and the Gamma test between genders and the gender differences in this association were analyzed by Log-binomial regression. RESULTS: The total prevalence of self-harm was 13.7% with no significant gender difference (χ2 =0.352, P = 0.553). The prevalence of self-harm in girls decreased with age (G = -0.163, P < 0.001). Self-harm was associated with drinking behaviors in both boys and girls. The Log-binomial regression demonstrated that girls in the 16-19 years old group were at lower risk of self-harm than girls in the 12-15 years old group while this association was weaker in boys (1.493 vs 1.128). The higher OR for self-harm was found among girls with early drinking experiences compared with boys (2.565 vs 1.863). Girls who had previously drunk (i.e. drunk at least once) (2.211 vs 1.636), were currently drinking (3.400 vs 2.122) and performed binge drinking (6.357 vs 3.924) were at greater risk of self-harm than boys. CONCLUSION: Among high school students, self-harm has a significant positive association with drinking and girls with drinking behaviors are at higher risk of suffering self-harm. Identifying adolescents' drinking behaviors is of vital importance to self-harm prevention and special attention should be focused on younger girls.

[Study on the trend of obesity prevalence among primary and middle school students in Beijing, from 1985 to 2005].

OBJECTIVE: To study the prevalence and trend of obesity among primary and middle school students in Beijing from 1985 to 2005. METHODS: Morphological data of students aged 7-18 from the National Physical Fitness and Health Surveillance of Chinese School Students in Beijing in 1985, 1995, 2000 and 2005 was analyzed with methods of cross-sectional study. The prevalence of obesity was calculated, and its secular trends was characterized. RESULTS: The prevalence of obesity among students aged 7-18 in Beijing were 0.65%, 3.40%, 5.23% and 8.53% respectively in the four surveillance programs with obvious rising trend which had an increase. In 2005, it was indicated that the obesity prevalence of subgroups were significantly different from each other. It was higher for males (11.11%) than females (5.98%), also for students aged 10-12 (11.63%). In rural schools (6.60%) it was much lower than in urban (10.38%), but the areas with high SES was deemed to have a lower prevalence. CONCLUSION: In the last two decades, among primary and middle school students in Beijing, obesity had changed its characteristics from sporadic to epidemic with the features of both developed and developing countries.