Association of Internet Addiction With Nonsuicidal Self-injury Among Adolescents in China.

Importance: Both nonsuicidal self-injury (NSSI), defined as the direct, deliberate damage of one's body tissue without suicidal intent, and internet addiction among adolescents are public health concerns. However, the possible association of NSSI with internet addiction is not well understood. Objective: To examine the occurrence of internet addiction with NSSI and any sex differences among Chinese adolescents. Design, Setting, and Participants: A multicenter, cross-sectional, survey study was conducted from February 18 to October 15, 2015, among adolescents aged 11 to 20 years from 343 classes in 45 public high schools across 5 provinces of China. Data analysis was performed from August 1, 2018, to March 1, 2019. Exposures: Possible internet addiction and internet addiction. Main Outcomes and Measures: Less-frequent (1-4 times) NSSI and more-frequent (≥5 times) NSSI were surveyed using the Chinese version of the Functional Assessment of Self-Mutilation. Results: A total of 15 623 students (8043 male [51.5%] and 7580 female [48.5%]) aged 11 to 20 years (mean [SD] age, 15.1 [1.8] years) participated. Of these, 4670 participants (29.9%) met the criteria for possible internet addiction and 509 participants (3.3%) met the criteria for internet addiction. A total of 2667 students (17.1%) engaged in less-frequent NSSI, while 1798 students (11.5%) engaged in more-frequent NSSI in the 12 months preceding the survey. Both possible internet addiction and internet addiction were associated with less-frequent or more-frequent NSSI. The adjusted odds ratios were 1.29 (95% CI, 1.17-1.42) for possible internet addiction and 1.41 (95% CI, 1.11-1.80) for internet addiction for less-frequent NSSI; for more-frequent NSSI, the adjusted odds ratios were 1.75 (95% CI, 1.56-1.96) for possible internet addiction and 2.66 (95% CI, 2.10-3.38) for internet addiction. These associations were similarly observed among age groups of 11 to 14, 15 to 17, and 18 to 20 years. No sex disparities were found in the associations of internet addiction with NSSI, except among adolescents aged 11 to 14 years, where the odds ratios for possible internet addiction with less-frequent NSSI were higher in male adolescents (1.53; 95% CI, 1.25-1.88) than female adolescents (1.13; 95% CI, 0.90-1.47). Conclusion and Relevance: Internet addiction appears to be associated with NSSI, and the findings of this study suggest that the association was similar between male adolescents and female adolescents. These data suggest that evaluation of the risk of NSSI for adolescents in association with internet addiction may help health care professionals in developing preventive interventions for NSSI.