Global index of lifestyle quality and non-suicidal self-injury in the SESSAMO project: a Spanish adolescents cohort.

Adolescents' failure to embrace healthy lifestyles constitutes a serious public health issue, such that its relationship to non-suicidal self-injury (NSSI) merits further research. The aim of the study was to ascertain the association between a Global Index of Lifestyle Quality (GILQ) and the presence of NSSI. Cross-sectional analysis of a sample of 2nd- to 4th-year ESO students (Obligatory Secondary Education, from ages 14 to 16) recruited for the SESSAMO project, a multicenter prospective cohort study. Exposure variables were collected, including eating patterns, physical activity, screen use, the consumption of cannabis, alcohol and tobacco, risky sexual behavior, gambling, spend time with friends, and sleep quality. To determine the presence of NSSI, a validated questionnaire was administered. The association between different lifestyles and the presence of NSSI was analyzed through multivariate logistic regression models. 2042 adolescents were included. Physical activity, screen use, risky sexual behavior, sleep quality, and daytime sleepiness showed inverse and statistically significant associations with the presence of NSSI in multivariate models. A higher lifestyle score was associated with a 71% reduction in the likelihood of engaging in NSSI (OR for extreme quartiles of GILQ adherence =0.29; 95% CI = 0.15-0.57). The result was similar when boys and girls were analyzed separately. A healthy lifestyle was inversely associated with the presence of NSSI in this sample of Spanish adolescents. Lifestyles could function as potential predictors of NSSI.