How should obstructive sleep apnea be confirmed and what is the first‑line therapy?

Diagnosis and First-Line Therapy for Obstructive Sleep Apnea

In-laboratory polysomnography (PSG) is the gold standard for confirming obstructive sleep apnea, and continuous positive airway pressure (CPAP) is the first-line therapy for all OSA phenotypes.

Diagnostic Confirmation

Gold Standard Testing

• In-laboratory polysomnography (Type I PSG) remains the definitive diagnostic test for OSA, measuring comprehensive parameters including EEG, EOG, EMG, airflow, respiratory effort, oxygen saturation, and ECG 1, 2.
• PSG must be performed in an AASM-accredited sleep center under supervision of a board-certified sleep medicine physician 1, 3.
• A technically adequate study requires a minimum of 4 hours of interpretable data obtained during the patient's habitual sleep period 1, 3.

Diagnostic Criteria

• OSA is diagnosed when either: (1) ≥5 obstructive respiratory events per hour (apneas, hypopneas, or RERAs) plus symptoms (daytime sleepiness, snoring, witnessed apneas, or gasping/choking), or (2) ≥15 obstructive events per hour even without symptoms 2, 4, 5.
• The apnea-hypopnea index (AHI) stratifies severity: mild (5-14 events/hour), moderate (15-29 events/hour), severe (≥30 events/hour) 6, 5.

Home Sleep Apnea Testing (HSAT) - Limited Role

HSAT may be used only in highly selected patients who meet all of the following criteria 1:

• High pretest probability of moderate-to-severe OSA based on clinical evaluation 1, 4
• No significant comorbidities: heart failure, COPD, neuromuscular disease, stroke history, chronic opioid use 1, 2
• No severe insomnia or suspected comorbid sleep disorders (periodic limb movements, narcolepsy, parasomnias) 1
• Device must include minimum sensors: nasal pressure, chest/abdominal respiratory inductance plethysmography, and oximetry 1, 3
• Testing supervised by board-certified sleep medicine physician within an AASM-accredited program 1, 3

Critical Pitfall: When HSAT Fails

If HSAT is negative, inconclusive, or technically inadequate, PSG must be performed - do not repeat HSAT, as the second test will likely also fail 1, 3. HSAT underestimates OSA severity by 10-26% and has false-negative rates of 3-18%, particularly for mild-to-moderate disease 1, 3, 2.

Who Requires PSG (Not HSAT)

Mandatory PSG indications include 1, 2:

• Moderate-to-severe pulmonary disease (COPD, restrictive lung disease)
• Congestive heart failure or significant cardiac arrhythmias
• Neuromuscular conditions with potential respiratory muscle weakness
• History of stroke or chronic opioid medication use
• Severe insomnia or suspected non-respiratory sleep disorders
• Morbid obesity with suspected obesity hypoventilation syndrome

First-Line Therapy

CPAP as Gold Standard

The American Academy of Sleep Medicine recommends continuous positive airway pressure (CPAP) as the gold standard initial treatment for all OSA phenotypes, with superior reduction in AHI, arousal index, and improvement in oxygen saturation compared to all alternatives 2, 7, 6.

CPAP Initiation Protocol

• Treatment should be initiated immediately following diagnostic confirmation when AHI ≥15/hour or AHI ≥5/hour with significant symptoms 3, 2.
• CPAP pressure is titrated during attended PSG or via auto-titrating CPAP devices 7, 8.
• Early follow-up within 1-2 weeks is essential to assess adherence, mask fit, and side effects 3, 2.

Split-Night Protocol

• If moderate-to-severe OSA is documented during the first 2 hours of diagnostic PSG, CPAP titration may be performed during the same night to expedite treatment 3, 7.

Adjunctive Weight Loss

Weight loss is recommended for all overweight and obese patients (BMI >25 kg/m²), as it improves AHI and provides cardiovascular benefits beyond OSA treatment 2, 6, 5.

Alternative Therapies - Second-Line Only

Alternative treatments are reserved for patients who refuse or cannot tolerate CPAP 2, 9, 5:

• Mandibular advancement devices (MADs): For mild-to-moderate OSA or CPAP-intolerant patients 9, 5
• Positional therapy: For position-dependent OSA (supine-predominant) 9, 6
• Hypoglossal nerve stimulation: For moderate-to-severe OSA with CPAP failure and specific anatomic criteria 9, 5
• Upper airway surgery: Insufficient evidence for first-line use; reserved for anatomic obstruction unresponsive to CPAP 6, 5

Common Pitfalls to Avoid

• Do not rely on absence of daytime sleepiness to rule out OSA - many patients with severe OSA do not report sleepiness 4.
• Do not use screening questionnaires (STOP-BANG, Epworth) alone for diagnosis - objective testing is always required 1, 4, 6.
• Do not assume HSAT is equivalent to PSG - it systematically underestimates disease severity and misses 10-26% of cases 1, 3, 2.
• Do not delay treatment in high-risk patients (commercial drivers, severe cardiovascular disease) - expedite PSG and CPAP initiation within one month 3.

Treatment Outcomes

CPAP effectively reduces daytime sleepiness, improves blood pressure control, and decreases cardiovascular morbidity, though mortality benefit has not been definitively demonstrated in randomized trials 8, 5. Adherence rates are variable (40-70%) and improve with early patient education, mask optimization, and heated humidification 6, 8, 5.