BackgroundAdolescents with immature mind and unstable emotional control are high-risk groups of non-suicidal self-injury (NSSI) behavior. We meta-analyzed the global prevalence of NSSI and prevalence of NSSI characteristics in a non-clinical sample of adolescents between 2010 and 2021.MethodsA systematic search for relevant articles published from January 1, 2010 to June 30, 2021 was performed within the scholarly database search engines of CBM, CNKI, VIP, Wanfang, PubMed, Web of Science, PsycINFO, and Embase. Eligibility criteria were as follows: provided cross-sectional data on the prevalence of NSSI; the subjects were non-clinical sample adolescents; and a clear definition of NSSI was reported. We used the following definiton of NSSI as our standard: the deliberate, self-inflicted destruction of body tissue, such as cutting, burning, and biting, without attempted suicide. The quality evaluation tool for cross-sectional studies recommended by the JBI was used. The global prevalence of NSSI was calculated based on the random-effects model by Comprehensive Meta-analysis version 3.0. Subgroup analyses were performed to compare the prevalence according to sex, living place, smoking or drinking history, and family structure.ResultsSixty-two studies involving 264,638 adolescents were included. The aggregate prevalence of NSSI among a non-clinical sample of adolescents was similar between over a lifetime (22.0%, 95% CI 17.9–26.6) and during a 12-month period (23.2%, 95% CI 20.2–26.5). Repetitive NSSI was more common than episodic NSSI (20.3% vs. 8.3%) but the frequency of mild injury (12.6%) was similar to that of moderate injury (11.6%). Multiple-method NSSI occurred slightly more often compared than one-method NSSI (16.0% vs. 11.1%). The top three types of NSSI in adolescents were banging/hitting (12.0%, 95% CI 8.9–15.9), pinching (10.0%, 95% CI 6.7–14.8), and pulling hair (9.8%, 95% CI 8.3–11.5), and the least common type was swallowing drugs/toxic substances/chemicals (1.0%, 95% CI 0.5–2.2). Subgroup analyses showed that being female, smoking, drinking, having siblings, and belonging to a single-parent family may be linked to higher prevalence of NSSI.ConclusionThis meta-analysis found a high prevalence of NSSI in non-clinical sample of adolescents, but there are some changes in severity, methods, and reasons. Based on the current evidence, adolescents in modern society are more inclined to implement NSSI behavior by a variety of ways, which usually are repetitive, and moderate and severe injuries are gradually increasing. It is also worth noting that adolescents with siblings or in single-parent families are relatively more likely to implement NSSI behavior due to maladjustment to the new family model. Future research needs to continue to elucidate the features and risk factors of NSSI so as to intervene in a targeted way.LimitationThe limitation of this study is that the heterogeneity among the included studies is not low, and it is mainly related to Chinese and English studies. The results of this study should be used with caution.Systematic review registration[www.crd.york.ac.uk/prospero/], identifier [CRD42022283217].

Background: Non-suicidal self-injury (NSSI) is being increasingly recognized as a prominent mental health concern, especially among adolescents. In psychiatric clinical samples, its incidence is high and difficult to identify. However, few studies have explored the NSSI behavior of psychiatric hospitalized adolescents. This study aimed to explore the influencing factors of NSSI according to the Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5) in adolescents admitted to the psychiatric department.Methods: In this cross-sectional study, by convenient sampling, a total of 505 psychiatric adolescent inpatients aged 10-19 years completed questionnaires to record details of sociodemographic characteristics, the NSSI questionnaire, the Child Psychological Abuse and Neglect Scale (CPANS), the self-report version of the Strengths and Difficulties Questionnaire (self-report SDQ), the Coping Style Scale for Middle School Students (CSSMSS), which were compared between NSSI inpatients and non-NSSI inpatients. This study used the diagnostic criteria for NSSI disorder in DSM-5: adolescent patients who have NSSI behaviors for more than 5 times in the past 1 year are called NSSI. A multiple logistic regression model was built to explore the relationships among general information, CPANS, SDQ, CSSMSS, and NSSI. Risk for NSSI is quantified by odds ratio (OR) with 95% confidence interval (CI). Results:The results showed that 77.82% (n=393) of adolescent inpatients had NSSI, and 80.0% were female (n=404). NSSI adolescent inpatients experienced more family scolding, psychological abuse, and neglect and showed more positive attitudes toward NSSI than non-NSSI adolescent inpatients. However, after controlling for covariables, the difference disappeared. NSSI behavior was significantly associated with female (OR =2.391, 95% CI: 1.396-4.097, P=0.002), younger age (10-14 years old) (OR =1.876, 95%