Sleep apnea, a common problem involving short periods when breathing stops during sleep, is often seen in stroke patients and appears to be associated with an increased risk of death, Swiss researchers report in the medical journal Stroke.However, upon further analysis, the only single factor that increased the risk of death after stroke was older age.Dr. Claudio L. Bassetti of Poliklinik, Zurich and colleagues note that despite being widespread, risk factors and other characteristics of sleep apnea in stroke patients are not widely known.To investigate further, the researchers initially studied 152 patients who had a stroke.Three days after the stroke, about 17 percent of the patients had evidence of sleep apnea and related problems. As time passed, the breathing problem resolved in 40 percent of patients.A variety of factors, including older age, being male and having diabetes and high blood pressure were more common in the patients with sleep-related breathing problems. Many of the stroke patients required long-term treatment with a breathing therapy called continuous positive airway pressure.As noted, the risk of death after stroke rose as the patient's sleep-related breathing problems worsened. Twenty-two percent of stroke patients with severe breathing impairment died compared with 8 percent who had minimal or no breathing difficulties.Still, the researchers point out that further analysis identified age as the only independent risk factor for death.