SLEEP: Single Question Aids Restless Leg Diagnosis

SALT LAKE CITY, June 22 ? A restless leg syndrome diagnosis can be ruled out by a single question, a researcher said here, a question that has achieved an international consensus.

If people answer no to the question, no further work is needed, said Raffaele Ferri, M.D., of the Oasi Institute for Research on Mental Retardation and Brain Aging in Troina, Italy, at Sleep 2006, the joint meeting of the Sleep Research Society and the American Academy of Sleep Medicine.

On the other hand, Dr. Ferri told researchers, a few people answer yes even though they don't actually have restless leg syndrome, and in that case physicians need to delve deeper, using standard techniques to arrive at a diagnosis.

The question, developed by the International RLS Study Group on the basis of standard diagnostic criteria, is:

"When you try to relax in the evening or sleep at night, do you ever have unpleasant, restless feelings in your legs that can be relieved by walking or movement?"

The standard criteria established by the International RLS Study Group consist of four questions about differing aspects of the syndrome; the single question is intended to capture enough information to allow a busy physician to quickly rule out those unlikely to have the condition.

Dr. Ferri's report was one of several here evaluating the single question in various populations. All the studies concluded that the single-question approach is valuable, although not all showed specificity and sensitivity as high as the Italian study.

With colleagues, Dr. Ferri enrolled 521 patients - 122 with a diagnosis of restless leg syndrome -- at his neurological clinic in Sicily, as well as 45 healthy controls.

When the 566 patients were asked the question, 127 answered yes - all 112 restless leg syndrome patients and 15 others. The remaining 439 patients all said no.

In other words, Dr. Ferri said, the question picks up all restless leg syndrome patients for a sensitivity of 100%, and only captures a few false positives for a specificity of 96.7%.

The study is "excellent and convincing," said Wayne Hening, M.D., Ph.D., of the University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School in New Brunswick, N.J. But, he noted, the sensitivity and specificity of the question vary depending on the population being surveyed.

Dr. Hening and colleagues reported here on a study that covered two populations: people with a confirmed diagnosis of the restless leg syndrome and people from a case-control family study of restless leg syndrome, most of whom did not have the syndrome.

In the 74 restless leg syndrome patients, the question had a sensitivity of 100%; in the family study, all 26 of those diagnosed with restless leg syndrome answered positively and 35 of the 44 without restless leg syndrome answered negatively for a sensitivity of 100% and a specificity of 80%, Dr. Hening and colleagues reported.

The study "confirms that this single question is highly sensitive for restless leg syndrome and reasonably specific," the researchers said, and will allow physicians to restrict detailed diagnostic questioning to those most likely to have the syndrome.

Similar results were reported by Howard Shapiro, M.D., of the Akron (Ohio) General Medical Center, and Denise Sharon, Ph.D., of Tulane in New Orleans.

Dr. Shapiro and colleagues administered the question to 150 sequential patients referred to a sleep center; the patients also answered the four standard diagnostic questions established by the International RLS Study Group. The sensitivity of the single question was 93%, Dr. Shapiro reported, and the specificity was 70%.

Dr. Sharon and colleagues administered the question to 100 patients at their initial clinical screening; the answers were compared to the eventual physician diagnosis. Overall, they reported, sensitivity was 91% and specificity was 82%. Interestingly, they reported, the sensitivity was higher in women (at 100%) than in men (at 75%).