Validation of the Three-Item Insomnia Severity Index Short Form in Young Adult Cancer Survivors: Comparison with a Structured Diagnostic Interview.

Chronic insomnia affects ∼25% of young adult cancer survivors (YACS) but is often overlooked in routine follow-up. A recently introduced three-item version of the Insomnia Severity Index (ISI-3) was compared with a diagnostic interview (SCID-5) in 250 YACS (ages 18-40) to evaluate its validity in this population. The ISI-3 had good discrimination compared with the SCID-5 (area under the receiver operating characteristic curve = 0.88). Although no ISI-3 cutoff met study criteria for both sensitivity (≥0.85) and specificity (≥0.75), an ISI-3 cutoff of ≥4 had high sensitivity (94%) and moderate specificity (70%), and is recommended as the first step in a two-step screening procedure.