Objective: To understand parent-child cohesion and problematic mobile phone use among middle school students in Shenzhen, and to provide a refevence for conducting the relevant control and prevention work . Methods: A total of 3 992 students from 5 junior high schools and 5 senior high schools in Shenzhen were selected by using stratified cluster sampling method. Problematic mobile phone use and parent-child cohesion were investigated, and their association was analyzed. Results: The average score of father-child cohesion and mother-child cohesion was (34.34±9.67) and (38.14±8.35), respectively. Mother-child cohesion score was higher than father-child cohesion score in both junior and senior middle school students(t=12.07, 14.41, P<0.01). Father-child cohesion (r=-0.20, P<0.01) and mother-child cohesion (r=-0.17, P<0.01) was negatively correlated with problematic mobile phone use. The lower the score of parent-child cohesion, the higher the score of problematic mobile phone use. Conclusion Family plays an important role in the prevention and control of problematic mobile phone use among middle school students. Improving parent-child cohesion and building a good parent-child relationship may help prevent problematic mobile phone use.

Objective: To investigate psychological sub-health status and its correlation with suicidal behaviors among middle school students in Shenzhen, so as to provide reference for early prevention of suicide. Methods: A total of 4 014 students from 5 junior high schools and 5 senior high schools in Shenzhen were selected as the subjects. The status of psychological sub-health and suicidal behaviors were assessed, and their correlation was analyzed. Results: The detection rates of psychological sub-health, suicide ideation, suicide plan and suicide attempts were 21.38%, 24.66%, 11.81% and 3.64% respectively. The detection rates of suicidal ideation, suicide plan and suicide attempts among students with high level of psychological sub-health status were significantly higher than those without psychological sub-health status(P<0.01). Correlation analysis showed that the number of psychological sub-health symptoms was positively correlated with the number of suicidal ideations, suicide plans and suicide attempts(P<0.01). Conclusion Psychological health status of adolescents in Shenzhen is not optimistic. There is a correlation between psychological sub-health status and suicidal behaviors. More attention should be paid to suicide prevention among students with psychological sub-health status.

Objective: To investigate the associated factors of myopia among primary and secondary school students in Shenzhen, and to provide reference for the prevention and control of myopia. Methods: By stratified cluster sampling, 3 073 students of 14 schools including primary,junior,regular and vocational senior schools from two districts in Shenzhen were selected and investigated. Results: For primary school students, the time of using computer for 2-<3 hours per day (OR=2.23，95%CI=1.19-4.20) , and no physical education class(2 sections per week OR=0.34, 95%CI=0.13-0.91; 4 sections per week OR=0.23, 95%CI=0.08-0.62; 5 sections or more per week OR=0.33, 95%CI=0.11-0.97) were positively associated with myopia. Teachers finishing class on time at break (occasionally delaying OR=1.99, 95%CI=1.51-2.63; frequently delaying OR=2.07, 95%CI=1.29-3.30), taking 0.5-1 hour break when using eyes at close range (1-<2 hours OR=1.33，95%CI=1.03-1.70; ≥3 hours OR=1.87, 95%CI=1.17-3.00), no parents with myopia(one parent with myopia OR=1.69, 95%CI=1.32-2.17; two parents with myopia OR=2.13, 95%CI=1.50-3.02) were negatively associated with myopia. For junior high school students, without parents with myopia (one parent with myopia OR=3.27, 95%CI=2.17-4.94; two parents with myopia OR=5.38, 95%CI=2.78-10.42) was the protective factor of myopia. For senior high school students, male (female OR=1.52, 95%CI=1.07-2.14), doing eye exercises twice a day in school (OR=0.41, 95%CI=0.23-0.75), and accumulating outdoor activities for ≥2 hours a day (OR=0.70, 95%CI=0.49-1.00) were negatively associated with myopia. Conclusion There are different risk factors for myopia among different students in Shenzhen. Students with high risk factors are the key objects of prevention and control.