Classification of Indian Scale for Assessment of Nomophobia (ISAN) among Indian college students: Evidence from ROC curve analysis

ABSTRACT Background: Nomophobia, or the fear of being without a smartphone, is a growing concern linked to excessive smartphone use. While the Indian Scale for Assessment of Nomophobia (ISAN) has been validated, its clinical utility in identifying nomophobia severity among Indian youth required further exploration. Aim: To establish appropriate ISAN cut-off scores to classify nomophobia severity levels using receiver operating characteristic (ROC) curve analysis. Materials and Methods: This study employed a cross-sectional design across three centers in India with 948 participants. Nomophobia levels were categorized using quartile-based classifications for both the Nomophobia Questionnaire (NMP-Q) and ISAN scales. Agreement between these classifications was initially assessed using weighted kappa statistics. ROC curve analysis was then conducted to identify optimal ISAN cut-off scores corresponding to mild, moderate, and severe nomophobia, using NMP-Q as the reference. Post-ROC, agreement was reassessed, and the sensitivity, specificity, and predictive validity of ISAN were evaluated by comparing it with NMP-Q. Results: A cut-off score of 58 demonstrated the highest sensitivity (81.20%) with a corresponding Youden’s index of 0.45. In contrast, a cut-off score of 74 yielded the highest Youden’s index (0.50), associated with a specificity of 80.17%. Subsequently, the ROC curve analysis classified nomophobia severity, with scores of below and equal to 58 (≤58) indicating mild nomophobia, 59–73 representing moderate nomophobia, and scores 74 and above (≥74) reflecting severe nomophobia. Conclusion: The findings confirm ISAN as a valid tool for detecting and categorizing nomophobia severity. Its integration into college-based screenings can help identify and support at-risk youth early.