The most effective nonsurgi- cal approaches require intensive behavioral counseling, possibly with food substitution. Research is ongoing to understand the biology of obesity and to develop more effective and convenient treatments, which may include pharmacological approaches to appetite sup- pression. Right now, however, trials of counseling and food substitution could be implemented safely and are urgently needed. 4.6. Obstructive Sleep Apnea Recommendations for Obstructive Sleep Apnea Referenced studies that support recommendations are summarized in online Data Supplements 18 and 19. COR LOE Recommendations In patients with an ischemic stroke or TIA and OSA, treatment with positive airway pressure (eg, continuous positive airway pressure [CPAP]) can be beneficial for improved sleep apnea, BP, sleepiness, and other apnea- In patients with an ischemic stroke or TIA, an evaluation for OSA may be considered for diagnosing sleep apnea.302,303,315,316 Synopsis Sleep apnea is diagnosed by polysomnography to calcu- late the apnea-hypopnea index (AHI), the hourly sum of apneas (total cessation of airflow for 10 seconds) plus hypopneas (reduction in airflow by at least 30% for 10 seconds with reduced oxygen saturation). The threshold for diagnosis is AHI 5 with symptoms (eg, sleepiness) or Theprevalenceofmoder- ate to severe sleep apnea (AHI >15) among US adults 50 to 70 years of age is estimated to be 10%.318 Prevalence is higher in men than women and increases sharply with age and BMI. 