Context: Distinctive diagnostic classification schemes for insomnia diagnoses are available, but the optimal insomnia nosology has yet to be determined.
Objectives: To test the reliability and validity of insomnia diagnoses listed in the American Psychiatric Association's DSM-IV-TR and the International Classification of Sleep Disorders, second edition (ICSD-2).
Design: Multitrait-multimethod correlation design.
Setting: Two collaborating university medical centers, with recruitment from January 2004 to February 2009.
Participants: A total of 352 adult volunteers (235 of whom were women) who met research diagnostic criteria for insomnia disorder.
Main outcome measures: Goodness-of-fit ratings of 10 DSM-IV-TR and 37 ICSD-2 insomnia diagnoses for each patient. Ratings were provided by 3 clinician pairs who used distinctive assessment methods to derive diagnostic impressions. Correlations computed within and across clinician pairs were used to test reliability and validity of diagnoses.
Results: Findings suggested that the best-supported DSM-IV-TR insomnia categories were insomnia related to another mental disorder, insomnia due to a general medical condition, breathing-related sleep disorder, and circadian rhythm sleep disorder. The category of primary insomnia appeared to have marginal reliability and validity. The best-supported ICSD-2 categories were the insomnias due to a mental disorder and due to a medical condition, obstructive sleep apnea, restless legs syndrome, idiopathic insomnia, and circadian rhythm sleep disorder-delayed sleep phase type. Psychophysiological insomnia and inadequate sleep hygiene received much more variable support across sites, whereas the diagnosis of paradoxical insomnia was poorly supported.
Conclusions: Both the DSM-IV-TR and ICSD-2 provide viable insomnia diagnoses, but findings support selected subtypes from each of the 2 nosologies. Nonetheless, findings regarding the frequently used DSM-IV-TR diagnosis of primary insomnia and its related ICSD-2 subtypes suggest that their poor reliability and validity are perhaps due to significant overlap with comorbid insomnia subtypes. Therefore, alternate diagnostic paradigms should be considered for insomnia classification.