Does Restless Legs Syndrome Really Shorten Life Span?

It may surprise you, but restless legs syndrome (RLS) affects 7% to 10% of the U.S. population, with varying degrees of severity. In the most extreme cases of this neurological disorder, patients have the urge to move their legs in response to severe discomfort or pain, which often interferes with sleep and can also impact other daily activities.

Now, according to a recent article published in the journal Neurology, RLS may also increase the risk of death in men. The study, led by researchers at the Harvard School of Public Health, tracked 18,425 American men over an eight-year time span and found that patients with RLS had a 39% increased risk of death.

In many ways, these results raised more questions than they answered. The patients enrolled in the study were screened for conditions that could already predispose them to a higher risk of death, such as diabetes and kidney failure, but RLS was not actually determined as the cause of death. Instead, researchers just discovered a statistical link between men with the disorder and a higher risk of mortality that will need to be explored further with rigorous clinical studies.

Treatments for RLS
While a better understanding of RLS and its long-term impact on health are needed, there are FDA-approved drugs available to treat the symptoms of this disorder. GlaxoSmithKline (NYSE: GSK  ) brought a RLS drug, Requip, to market eight years ago, and the drug was also approved for Parkinson's disease. Total sales of the medication have been falling in recent years due to generic competition and reached only 164 million pounds ($257.5 million) in 2012. Until recently, GSK also had a second RLS drug called Horizant in collaboration with biotech company XenoPort (NASDAQ: XNPT  ) . GSK recently handed the rights to the drug back to XenoPort after sales failed to meet its expectations, and the biotech is now commercializing the drug alone.

RLS hasn't been a high-priority target for the pharma industry given the lackluster sales of Requip and Horizant, a third competitor of UCB's Neupro, and a number of generic alternatives. Impax Laboratories (NASDAQ: IPXL  ) was one of the few developing a new therapy, called IPX159, but Impax put the kibosh on the drug after it failed to meet its primary endpoint in a phase 2b study. According to its latest quarterly report, Impax has no other RLS drugs in development and seems to be focusing on getting its rejected Parkinson's disease drug Rytary back to the FDA for a second chance at approval.

Outlook
So, will the results of this study cause widespread panic over the long-term health implications of RLS? And from an investing point of view, will there be a dramatic spike in RLS drug sales? The answer to both questions, in my opinion, is no. The Neurology article has shone the spotlight on a poorly understood disease, but clinicians still need to run more trials and gather evidence before a causal relationship between RLS and mortality is established. Academic interest in RLS research should pick up in the coming years, but I think near-term drug sales in this space will be static.

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