Correlation between systemic immune-inflammation index and suicide attempts in children and adolescents with first-episode, drug-naive major depressive disorder during the COVID-19 pandemic

Objective: This study aims to investigate the association between the systemic immune-inflammatory index (SII) and suicide attempt (SA) in children and adolescents with first-episode, drug-naïve Major Depressive Disorder (MDD) during the COVID-19 pandemic. Methods: A retrospective study was conducted on 263 MDD patients hospitalized at the Third Hospital of Fuyang City between 2020 and 2022. Patients were categorized into two groups based on the presence of previous SA. The study compared the differences in SII and clinical characteristics between the two groups and used the receiver operating characteristic (ROC) curve to determine the optimal critical value of SII and the area under the curve. Binary logistic regression was used to analyze the independent risk factors for SA. Results: Compared with the patients without SA history, the patients with a personal history of SA had a higher mean HDRS scores (Z=− 2.369, p=0.018), higher mean neutrophil count (Z=− 2.870, p=0.004), higher mean platelet count (Z=− 2.155, p=0.031), and higher mean SII (Z=− 3.170, p=0.002). The optimal critical SII determined by the ROC curve was 548.15 (sensitivity = 63.2%, specificity = 83.1%), and the area under the curve was 0.661. After adjusting for gender, age, BMI, illness duration and HDRS score, the risk of total SA in patients with high SII was 8.296 times higher than in those with low SII (OR = 8.296, 95% CI: 3.803– 18.095, P < 0.001), The risk of recent SA was 13.922 times higher in patients with high SII than in those with low SII (OR = 13.922, 95% CI: 5.587– 34.693, p < 0.001). However, high SII was not a risk factor for past SA (OR = 0.547, 95% CI: 0.062– 4.842, P=0.587). Conclusion: SII may be an inexpensive, easily accessible strategy that can assist in determining suicide risk in adolescents with MDD.