The diagnostic validity of the Athens Insomnia Scale.
OBJECTIVE
To provide documentation for the diagnostic validity of the Athens Insomnia Scale (AIS), a self-assessment psychometric tool which has previously shown high consistency, reliability and external validity for the evaluation of the intensity of sleep difficulty.


METHODS
The AIS was administered to a total of 299 subjects (105 primary insomniacs, 100 psychiatric outpatients, 44 psychiatric inpatients and 50 nonpatient controls) who were also assessed for the ICD-10 diagnosis of "nonorganic insomnia" blindly in terms of the AIS scores.


RESULTS
176 subjects were identified as insomniacs and 123 as noninsomniacs. Logistic regression of AIS total score against the ICD-10 diagnosis of insomnia demonstrated that a score of 6 is the optimum cutoff based on the balance between sensitivity and specificity. When diagnosing individuals with a score of 6 or higher as insomniacs, the scale presents with 93% sensitivity and 85% specificity (90% overall correct case identification). For this cutoff score, in the general population, the scale has a positive predictive value (PPV) of 41% and a negative predictive value (NPV) of 99%. For the same cutoff score, among unselected psychiatric patients, the PPV was found to be 86% and the NPV 92%. Other cutoff scores can be also considered, however, depending on the importance of avoiding false positive or false negative results; for example, for a cutoff score of 10, the PPV in the general population reaches about 90% without the NPV becoming lower than 94%.


CONCLUSIONS
The AIS can be utilized in clinical practice and research, not only as an instrument to measure the intensity of sleep-related problems, but also as a screening tool in reliably establishing the diagnosis of insomnia.
Soldatos
Constantin R
CR
Sleep Research Unit, Department of Psychiatry, Athens University Medical School, Athens, Greece. egslelabath@hol.gr
Dikeos
Dimitris G
DG
Paparrigopoulos
Thomas J
TJ
D000328:Adult; D000368:Aged; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011569:Psychiatric Status Rating Scales; D012016:Reference Values; D012044:Regression Analysis; D012680:Sensitivity and Specificity; D007319:Sleep Initiation and Maintenance Disorders / Q000145:classification* / Q000175:diagnosis*