Ohio ? Nine in every 10 patients awaiting weight-loss surgery suffer from sleep apnea, a much higher percentage than are typically diagnosed, a University Hospitals of Cleveland study has found.

In a group of 249 patients followed between December 2003 and August 2005, 19 percent had been diagnosed with obstructive sleep apnea. However, after all the patients were tested in sleep labs before surgery, it was found that 91 percent of those patients actually had the condition.

Obesity has long been seen as a contributing factor for sleep apnea, but most studies have estimated that 30 percent to 50 percent of obese people have sleep apnea.