Screening and Diagnosis of OSA - AASM Guidelines

1. Overview of AASM Diagnostic Framework

• Screening - identifying patients at increased risk using clinical tools and questionnaires
• Diagnosis - confirming OSA with objective sleep testing (PSG or HSAT)

"Clinical tools, questionnaires and prediction algorithms should not be used to diagnose OSA in adults without polysomnography or home sleep apnea testing (HSAT)." - AASM 2017 Guideline (Strong Recommendation)

2. Screening

Who to Screen

• Loud snoring (heard through closed doors)
• Witnessed apneas or gasping/choking during sleep
• Daytime hypersomnolence or fatigue
• Obesity (BMI >30 kg/m²) - 70% of OSA patients are obese; screening all obese patients is recommended
• Hypertension, especially drug-resistant
• Crowded upper airway, retrognathia, large neck circumference
• Male sex, age >50 years, menopause in women

Validated Screening Questionnaires

STOP-BANG Questionnaire

• Score 0-2: Low risk for OSA
• Score 3-4: Intermediate risk
• Score 5-8: High probability of moderate-to-severe OSA
• The STOP-BANG has high sensitivity but low specificity; it should not replace objective testing

Epworth Sleepiness Scale (ESS)

• Measures subjective daytime sleepiness across 8 situations (0-3 scale each, max 24)
• ESS >10: Clinically significant daytime sleepiness; OSA may be suspected
• Limitation: Not sensitive or specific enough to screen for OSA on its own
• More useful for symptom quantification and treatment monitoring

Berlin Questionnaire

• Validated in primary care settings
• Three categories: snoring/apneas, daytime sleepiness, hypertension/BMI
• High-risk classification if positive in 2+ categories

"The Berlin Questionnaire has been validated in a primary care setting and identifies patients likely to have OSA. Another often used screening questionnaire is the STOP-Bang survey, which has been used in preoperative anesthesia clinics to identify patients at risk of having OSA." - Harrison's Principles of Internal Medicine 22e

3. Diagnostic Testing - AASM Decision Framework

Two Diagnostic Pathways

A. Polysomnography (PSG) - Gold Standard

• EEG (sleep staging)
• EOG (eye movements)
• Chin and limb EMG (muscle activity, arousals)
• Nasal pressure transducer + oronasal thermistor (airflow)
• Thoracoabdominal bands (respiratory effort)
• SpO2 (pulse oximetry)
• ECG
• Body position + video

• Suspected OSA with significant cardiorespiratory disease (CHF, COPD, pulmonary hypertension)
• Potential respiratory muscle weakness (neuromuscular disease)
• Awake hypoventilation or suspected sleep-related hypoventilation/hypoxemia
• Chronic opioid medication use
• History of stroke
• Severe insomnia complicating the study
• Prior negative or inconclusive HSAT
• Suspected comorbid sleep disorders (narcolepsy, REM behavior disorder, periodic limb movement disorder)
• Pre-surgical evaluation for upper airway surgery or oral appliance therapy

B. Home Sleep Apnea Testing (HSAT) / Out-of-Center Sleep Testing (OCST)

• Comorbid cardiorespiratory disease
• Suspected hypoventilation
• Neuromuscular disease
• Stroke history
• Severe insomnia
• Suspicion of other sleep disorders
• Single HSAT is negative, inconclusive, or technically inadequate

"When a single HSAT is negative, inconclusive, or technically inadequate, polysomnography should be performed for the diagnosis of OSA." - AASM 2017 (Strong Recommendation)

4. Diagnostic Criteria and Severity Classification

Diagnostic Criteria (AASM/ICSD-3)

• Apnea: Cessation of airflow ≥10 seconds
• Hypopnea (AASM recommended): ≥30% reduction in airflow for ≥10 seconds + ≥3% SpO2 desaturation or cortical arousal
• RERA (Respiratory Effort Related Arousal): flow limitation with arousal but not meeting apnea/hypopnea criteria - counted in the RDI but not AHI

Note: CMS/Medicare uses a 4% desaturation criterion for hypopneas (more restrictive), while AASM recommends 3%.

Severity Classification

5. Inpatient Screening - 2025 AASM Update

• Conditional Recommendation: For medically hospitalized adults at increased risk for OSA, in-hospital screening as part of an evaluation and management pathway incorporating diagnosis + PAP treatment is suggested (rather than no screening).
• Screening modalities: validated questionnaires (STOP-BANG) and/or overnight high-resolution pulse oximetry
• Patients with established OSA diagnosis on active treatment should continue their treatment in hospital unless contraindicated
• A discharge management plan for timely outpatient diagnosis/follow-up is recommended for newly identified cases

6. Nocturnal Oximetry as a Supplemental Tool

• Part of an inpatient screening pathway
• A triage tool to prioritize who needs formal sleep testing
• Monitoring tool post-treatment

Summary Algorithm

Clinical suspicion of OSA
        ↓
Screening (history + ESS + STOP-BANG + physical exam)
        ↓
High pretest probability of moderate-to-severe OSA?
   YES ↓                           NO ↓
Comorbid medical/sleep disorder?   Proceed to HSAT
   YES → In-lab PSG
   NO  → HSAT
        ↓
HSAT negative/inconclusive?
   YES → In-lab PSG
   NO  → AHI ≥5 + symptoms OR AHI ≥15 → DIAGNOSIS
        ↓
Severity: Mild (5-14) / Moderate (15-29) / Severe (≥30)
        ↓
Treatment

• AASM 2017 Clinical Practice Guideline for Diagnostic Testing for Adult OSA (Kapur et al., J Clin Sleep Med 2017;13:479-504) - endorsed by World Sleep Society 2021
• AASM 2025 Inpatient OSA Guideline: Mehra et al., J Clin Sleep Med 2025 [PMID: 40838698]
• Fishman's Pulmonary Diseases and Disorders, 2-Volume Set
• Goldman-Cecil Medicine, Table 374-2
• Miller's Anesthesia, 10e
• Harrison's Principles of Internal Medicine 22e (2025)
• Cummings Otolaryngology Head and Neck Surgery