Polygraphy vs. polysomnography: missing osas in symptomatic snorers--a reminder for clinicians

Area of Science:

• Sleep Medicine
• Respiratory Physiology
• Diagnostic Accuracy

Background:

• Obstructive sleep apnea (OSA) is a common disorder characterized by repeated episodes of airway obstruction during sleep.
• Sleepiness and snoring are key symptoms that prompt diagnostic evaluation for OSA.
• Polygraphy (PG) is a portable diagnostic tool, while polysomnography (PSG) is the gold standard for OSA diagnosis.

Purpose of the Study:

• To evaluate the diagnostic utility of PG in identifying obstructive sleep apnea (OSA) in patients presenting with sleepiness and snoring.
• To compare the effectiveness of PG against polysomnography (PSG) in diagnosing OSA.
• To investigate the detection of respiratory arousals using PG.

Main Methods:

• One hundred eighty-seven adults with sleepiness and snoring underwent ambulatory PG.
• A subset of patients later underwent in-lab PSG, using updated hypopnea criteria that include arousal recognition.
• Validated questionnaires assessed anxiety, depression, and general health; specific PG indices (FLI, FlatI) were compared to PSG's RDI.

Main Results:

• Despite normal PG results, PSG revealed a median Respiratory Distress Index (RDI) of 11.0, indicating significant OSA in most patients (90% mild OSA, 64% moderate-severe OSA).
• The sensitivity and specificity of PG indices (FLI, FlatI) for detecting OSA were low (<70%).
• A high prevalence of psychological distress (49% anxiety, 35% depression) and poor general health (45%) was observed.

Conclusions:

• Ambulatory PG is inadequate for ruling out OSA, particularly when respiratory events are linked to arousals.
• Patients with symptoms of snoring and sleepiness, even with a normal PG, often have undiagnosed OSA and associated health issues.
• A full-night PSG is recommended for patients with persistent snoring and sleepiness symptoms, even if initial PG is normal.