From the Guidelines

For Adult patients with AHI (Apnea-Hypopnea Index) sleep apnea, treatment is recommended as follows:

Mild AHI (5-14 events per hour): Lifestyle modifications such as weight loss, avoiding sleeping on the back, and avoiding alcohol and sedatives before bedtime 1.
Moderate AHI (15-29 events per hour): Continuous Positive Airway Pressure (CPAP) therapy, with a pressure range of 5-15 cmH2O, or an oral appliance 1.
Severe AHI (30 or more events per hour): CPAP therapy, with a pressure range of 5-15 cmH2O, as the first line of treatment 1. In some cases, medications like Modafinil (100-200 mg daily) may be prescribed to help manage excessive daytime sleepiness 1. Some key points to consider:
The American College of Physicians recommends that all overweight and obese patients diagnosed with OSA should be encouraged to lose weight 1.
Mandibular advancement devices (MADs) reduce sleep apneas and subjective daytime sleepiness, improve quality of life compared with control treatments, and are recommended in the treatment of patients with mild to moderate obstructive sleep apnea (OSA) 1.
Cognitive behavioral therapy for insomnia (CBT-I) is effective in treating chronic insomnia and can be used in conjunction with OSA treatment 1. It is essential to consult a healthcare professional for a personalized treatment plan, as the severity of AHI sleep apnea and individual patient needs may vary.

From the Research

The diagnosis of obstructive sleep apnea (OSA) is typically based on the apnea-hypopnea index (AHI), which is the number of apneas and hypopneas per hour of sleep 2.
The American Academy of Sleep Medicine defines OSA as an AHI of at least 5 events per hour of sleep 2.
However, the definition of hypopneas has varied over the years, and recent studies suggest that scoring respiratory events associated with arousals should be included in the diagnosis of OSA 2.

Treatment of OSA depends on the severity of the disease and the patient's phenotype 3.
Continuous positive airway pressure (CPAP) therapy is a common treatment for OSA, but adherence to treatment can be a challenge 4.
Oral appliances, such as adjustable and fixed devices, can also be effective in treating OSA, especially in patients with mild to moderate disease 5.
The effectiveness of treatment can be estimated using the Effectiveness of Treatment Apnea-Hypopnea Index (ET-AHI), which takes into account the level of CPAP adherence necessary to achieve equivalence with surgical results 4.
Different OSA phenotypes, such as positional OSA, severe OSA in obese patients, and OSA with periodic limb movements, may respond differently to treatment, emphasizing the need for a more individualized approach 3.

The severity of individual obstruction events can affect the outcome of OSA treatment, and adjusting the AHI to account for this severity can provide valuable supplementary information for diagnosis and treatment 6.
Patient characteristics, such as age, body mass index (BMI), and disease severity, can also impact treatment effectiveness 5, 3.
The type of oral appliance used can also affect treatment outcomes, with adjustable devices producing greater reductions in obstructive events than fixed appliances 5.