Clinical significance criteria in the ICSD and DSM sleep disorder classifications: a content overlap analysis using the Jaccard index

Both the International Classification of Sleep Disorders (ICSD) and the sleep-wake disorders section of the Diagnostic and Statistical Manual of Mental Disorders (DSM) emphasize the importance of clinical judgment in distinguishing the normal from the pathological in sleep medicine. The fourth edition of the DSM (DSM-IV, 1994) introduced the clinical significance criterion (CSC) to standardize this judgment and enhance diagnostic reliability. This review conducts a theoretical and historical content analysis of CSC presence, frequency, and formulation in the diagnostic criteria of sleep disorders. Three steps were undertaken: i) selecting main sleep disorder classifications and main disorders within them, ii) systematically extracting CSC-related content, and iii) analyzing the evolution of CSC presence through quantification (Jaccard index) and visualization (radar plots). The fifth edition, text revision of the DSM (DSM-5-TR) includes CSC in five of nine main sleep disorders, compared to two in the third edition, text revision of the ICSD (ICSD-3-TR) (circadian rhythm sleep-wake disorder and nightmare disorder). The overlap between DSM-5-TR and ICSD-3-TR is moderate (Jaccard index = 0.40). The overlap between DSM versions is higher (0.53). Conversely, ICSD revisions exhibit minimal similarity (0.16). Radar plots reveal a gradual increase in CSC use within ICSD versions. These results highlight the variable application of CSC in sleep disorder classifications. Universal CSC inclusion may not be essential, but systematic discussion of its potential use can help refine diagnostic criteria. This refinement is important for accurately diagnosing sleep disorders and better differentiating the normal from the pathological, a major challenge in sleep medicine.