Simple tool may aid insomnia diagnoses

Mar 31 2014

By Laura Cowen, medwireNews Reporter

UK researchers have developed a “brief but versatile” tool, based on standard diagnostic criteria, to screen patients for insomnia disorder.

The Sleep Condition Indicator (SCI), described in BMJ Open and freely available online, provides “a dimensional perspective on sleep quality… a visual profile of night-time and daytime symptoms that the clinician can use in consultations and… indicative cut-off points for clinically-significant insomnia,” say its creators Colin Espie (University of Oxford) and colleagues.

The eight-item tool, based on Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition criteria, was tested in five validation studies comprising 30,941 individuals (71% women) who mostly regarded themselves as having average or better physical and mental health.

Using the SCI’s 5-point scale (0–4), where higher values indicate better sleep, study participants rated the time it takes them to get to sleep, how long they remain asleep, how many nights per week they have a problem with sleep and overall sleep quality. They also rated how poor sleep affected their mood, energy and relationships in the past month, how poor sleep affected concentration, productivity or ability to stay awake, how poor sleep troubled them in general and how long they had had a sleep problem.

The researchers then showed in a subgroup of 256 patients that the total SCI score (0–32) significantly and inversely correlated with two established screening instruments widely used in insomnia assessments: the Pittsburgh Sleep Quality Index and the Insomnia Severity Index (ISI).

Furthermore, applying an SCI cutoff of 16 or below correctly identified 89% of participants with a “probable insomnia disorder” when compared with an ISI cutoff of 15 or above, while an SCI score above 16 correctly identified 82% of those with “no insomnia disorder”.

To further simplify the SCI, Espie and team developed a short-form version that comprised just two items: how many nights per week there is a sleep problem and how troubled the patient is in general. Taken together, these two items predicted 82% of the variance in the full scale SCI and correlated strongly with the total SCI score.

The researchers suggest that these two items, focusing on the severity of the presenting complaint and the frequency of the sleep problem should be “the lead questions for a clinician to use in the context of their consulting room practice.”

They caution, however, that “studies of predictive validity with reference to independent clinical evaluation of insomnia disorder (the gold standard) are essential before firm conclusions can be made.”

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