Evidence suggests that suicidal behaviour arises from one's attempt to escape from unbearable situations or unbearable thoughts and feelings. These feelings of entrapment are usually assessed via the 16-item Entrapment Scale, but this is too long for routine use in clinical practice. The aim of this study was to develop a brief version of the full scale that reliably assesses entrapment. We used data collected from a clinical sample (n = 497) of patients following hospital-treated self-harm and a population-based sample (n = 3457) of young adults. Four items were selected that had both the highest factor loading and discriminatory parameters and that covered the theoretical constructs of internal and external entrapment. Correlations between the 4-item short-form and the 16-item full scale were nearly perfect (0.94 for the clinical sample, 0.97 for the population-based sample). When comparing the correlations between the short-form and the full scale with other clinical and psychological scales, the correlations were nearly identical. The 4-item Entrapment Scale Short-Form (E-SF) will provide very comparable information about entrapment for each respondent as the full scale will do. However, its brevity will increase the likelihood that the assessment of entrapment will be implemented into everyday clinical practice.
Keywords: Assessment; Entrapment; Item response analysis; Suicide.
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