Objective: To examine the relationship between the prevalence of self-reported myopia and outdoor activities among middle school students and to explore the influence factors of the self-reported myopia. Methods: A total of 12 979 participants were recruited from junior and senior middle school students in in Shenzhen, Nanchang, Zhengzhou and Shenyang by random cluster sampling method between December 2015 and March 2016. All participants completed an anonymous questionnaire to collect the information of demographic characteristics, self-reported myopia, outdoor activities, etc. 12 603 out of 12 979 copies of questionnaire were valid. The prevalence of self-reported myopia was compared among middle school students with different characteristics. Logistic regression models were used to analyze the relationship between myopia and outdoor activities. Results: The prevalence of self-reported myopia among middle school students was 69.6% (8 766/12 603); which was separately 52.1% (1 216/2 335) in seventh grader, 61.6% (1 459/2 369) in eighth grader, 69.0%(1 470/2 129) in ninth grader, 80.0% (1 812/2 265) in freshmen, 79.4% (1 622/2 042) in sophomore, and 81.1%(1 187/1 463) in junior. The prevalence of self-reported myopia showed an increasing trend with the increase of grade (χ(2)=639.67, P<0.001). The prevalence of self-reported myopia was separately 63.5%(4 927/7 756) in non-myopic parents group, 78.0%(2 664/3 415)in either myopic parent group, and 82.1%(1 175/1 432) in both myopic parents group(χ(2)=328.28, P<0.001). Outdoor activities were associated with self-reported myopia. Binary logistic regression analysis showed that the risk of self-reported myopia was significantly increased by always staying at home in extracurricular time among the middle school students (OR=1.58, 95%CI: 1.36-1.82). The risk of self-reported myopia were significantly decreased by always physical exercise and recreational activities after school among middle school students: the ORs were separately 0.67 (95%CI: 0.57-0.78) for physical exercise and 0.77 (95%CI: 0.64-0.92) for recreational activities. After stratified analysis by the parents' myopia status, in non-myopic parents group, exercise and recreational activities after school among middle school students decreased the risk of myopia: the ORs were separately 0.68 (95%CI: 0.55-0.82) for physical exercise and 0.76 (95%CI: 0.61-0.95) for recreational activities; in either myopic parent group, OR(95%CI) were separately 0.65 (0.47-0.90) and 0.68 (0.47-0.98). Conclusion: Outdoor activities was negatively associated with self-reported myopia among middle school students. However, the parents' myopia status may affect the protective effect.
目的： 分析中学生户外活动与自我报告近视的关联，探讨中学生自我报告近视的影响因素。 方法： 采用分层整群抽样方法，于2015年12月至2016年3月选取深圳、南昌、郑州和沈阳4个城市的12 979名中学生为调查对象，使用自编问卷调查中学生人口学特征、自我报告近视状况、最近一周户外活动情况等信息。共收回有效问卷12 603份。比较不同特征中学生自我报告近视率的差异；采用多因素二分类非条件logistic回归模型分析户外活动频率与中学生自我报告近视的关系。 结果： 中学生自我报告近视率为69.6%（8 766/12 603），初一至高三自我报告近视率分别是52.1%（1 216/2 335）、61.6%（1 459/2 369）、69.0%（1 470/2 129）、80.0%（1 812/2 265）、79.4%（1 622/2 042）、81.1%（1 187/1 463），随着年级升高呈上升趋势（χ(2)(趋势)=639.67，P<0.001）；双亲均不近视、单亲近视、双亲均近视的中学生自我报告近视率分别是63.5%（4 927/7 756）、78.0%（2 664/3 415）、82.1%（1 175/1 432）（χ(2)(趋势)=328.28，P<0.001）。户外活动行为与中学生自我报告近视之间存在关联，课外时间总是待在家中不外出的中学生自我报告近视发生风险较高(OR=1.58，95%CI：1.36~1.82)；放学后总是在校外进行户外体育锻炼及放学后总是在校外进行休闲娱乐活动中学生自我报告近视发生风险较低，OR（95%CI）值分别为0.67（0.57~0.78）、0.77（0.64~0.92）。按照父母近视情况进行分层分析，双亲均不近视的中学生中，放学后总是在校外进行户外体育锻炼和户外休闲娱乐活动者自我报告近视发生风险较低，OR（95%CI）值分别为0.68(0.55~0.82)、0.76(0.61~0.95)；单亲近视的中学生，放学后总是在校外进行户外体育锻炼和户外休闲娱乐活动者自我报告近视发生风险也较低，OR（95%CI）值分别为0.65（0.47~0.90）、0.68（0.47~0.98）。 结论： 户外活动与中学生自我报告近视呈负相关，父母近视情况可影响该保护作用。.
Keywords: Activities of daily living; Adolescent; Myopia.