The Severity of OSAHS as defined by the American Academy of Sleep Medicine Task Force (1999) is
AHI < 5 Normal
5 =< AHI <15 Mild
15 =< AHI <30 Moderate
30 =< AHI Severe
The above is the most widely used severity definition.
I know that British are using different criteria.
60-17. CONTINUOUS POSITIVE AIRWAY PRESSURE (CPAP)
Effective for services furnished between and including January 12, 1987 and March 31, 2002:
The diagnosis of OSA requires documentation of at least 30 episodes of apnea, each lasting a minimum of 10 seconds, during 6-7 hours of recorded sleep. The use of CPAP
is covered under Medicare
when used in adult patients with moderate or severe OSA for whom surgery is a likely alternative to CPAP
Effective for services furnished on or after April 1, 2002:
The use of CPAP
devices are covered under Medicare
when ordered and prescribed by the licensed treating physician to be used in adult patients with OSA if either of the following criteria using the Apnea-Hyopopnea Index (AHI) are met:
AHI ≥ 15 events per hour, or
AHI ≥ 5 and ≤ 14 events per hour with documented symptoms of excessive daytime sleepiness, impaired cognition, mood disorders or insomnia, or documented hypertension, ischemic heart disease or history of stroke.
The AHI is equal to the average number of episodes of apnea and hyponea per hour and must be based on a mimimum of 2 hours of sleep recorded by polysomnography using actual recorded hours of sleep (i.e., the AHI may not be extrapolated or projected).