Obstructive Sleep Apnea (OSA) Differential Diagnoses

Updated: Sep 15, 2020
  • Author: Himanshu Wickramasinghe, MD, MBBS; Chief Editor: Zab Mosenifar, MD, FACP, FCCP  more...
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Diagnostic Considerations

A diagnosis of narcolepsy may be delayed if obstructive sleep apnea (OSA) is considered the only condition. Patients should be routinely screened clinically for symptoms of narcolepsy. These patients do not typically have normal sleepiness when OSA has been treated; they may experience improvement in sleepiness, but it is important to question the diagnosis of sleepiness due to OSA despite ideal treatment. [137]

Indices for sleep-disordered breathing

The indices commonly used to assess sleep disordered breathing (SDB) are the apnea-hypopnea index (AHI) and the respiratory disturbance index (RDI).

The AHI is defined as the average number of episodes of apnea and hypopnea per hour. The RDI is defined as the average number of respiratory disturbances (obstructive apneas, hypopneas, and respiratory event–related arousals [RERAs]) per hour. If the AHI or RDI is calculated based on less than 2 hours of continuous recorded sleep, the total number of recorded events to calculate the AHI or RDI during sleep testing is at least the number of events that would have been required in a 2-hour period.

No universal consensus exists on whether the AHI or the RDI should be the standard index used to determine treatment by specialists and insurance carriers, with Medicare being the most confusing as it varies by region as to whether AHI and RDI can be used. This needs to be resolved as soon as possible. One study found that 30% of symptomatic patients would have been left untreated if the AHI were used rather the RDI. [33]

In the authors’ view, the RDI is preferable to the AHI because it includes flow-limitation events that end with arousals. The RDI is better suited to meet the new American Academy of Sleep Medicine (AASM) diagnostic criteria for OSA (see below). One study has demonstrated that use of the AHI alone leads to the underdiagnosis of OSA in 30% as compared to the use of the RDI. [33]

AASM diagnostic criteria for OSA

According to the Centers for Medicare & Medicaid Services criteria for the positive diagnosis and treatment of obstructive sleep apnea, [32] a positive test for OSA is established if either of the following criteria using the AHI or the RDI is met:

  • AHI or RDI greater than or equal to 15 events per hour, or

  • AHI or RDI greater than or equal to 5 and less than or equal to 14 events per hour with documented symptoms of excessive daytime sleepiness (EDS); impaired cognition; mood disorders; insomnia; or documented hypertension, ischemic heart disease, or history of stroke

The AASM has developed its own criteria, as listed in the International Classification of Sleep Disorders: Diagnostic and Coding Manual, Second Edition. [4] At least 1 of the following criteria must apply for OSA to be diagnosed:

  • The patient reports daytime sleepiness, unrefreshing sleep, fatigue, insomnia, and/or unintentional sleep episodes during wakefulness. The patient awakens with breath holding, gasping, or choking. The patient’s bed partner reports loud snoring, breathing interruptions, or both during the patient’s sleep.

  • Polysomnography (PSG) shows more than 5 scoreable respiratory events (eg, apneas, hypopneas, RERAs) per hour of sleep and/or evidence of respiratory effort during all or a portion of each respiratory event.

  • PSG shows more than 15 scorable respiratory events (eg, apneas, hypopneas, RERAs) per hour of sleep and/or evidence of respiratory effort during all or a portion of each respiratory event.

  • Another current sleep disorder, medical or neurologic disorder, medication use, or substance use does not better account for the patient’s condition.

Accreditation of sleep centers by the AASM is critical because there are still more centers that are unaccredited than there are centers that have chosen to meet the highest standards in the field (as evidenced by achieving AASM accreditation). Whether AASM accreditation translates into insurance companies deciding to pay for studies performed at an AASM-accredited center has yet to be determined, although in the authors’ opinion, payment should depend on achieving AASM accreditation.

include the following:

  • Chronic insufficient sleep

  • Dyspnea due to pulmonary edema

  • Idiopathic hypersomnia

  • Nocturnal panic attacks

  • Nonobstructive alveolar hypoventilation

  • Obesity-hypoventilation syndrome (pickwickian syndrome)

  • Periodic limb movement disorder

  • Simple snoring

  • Approximately 25% of narcoleptic persons also have obstructive sleep apnea [137] )

Differential Diagnoses