The utility of current criteria for split-night polysomnography for predicting CPAP eligibility

Traditionally, evaluation of obstructive sleep apnea (OSA) has consisted of a diagnostic polysomnogram (PSG), followed by a continuous positive pressure (CPAP) titration. However, to reduce costs, many third-party payers mandate performance of split-night studies (SPL), combining diagnostic and CPAP titration testing. We ascertained the utility of performing SPL for diagnosis and treatment of OSA.

We reviewed the PSG records of 200 patients suspected of having OSA. Using both American Academy of Sleep Medicine (AASM) and Medicare (CMS) criteria for scoring, we calculated the sensitivity, specificity, positive (PPV), and negative predictive value (NPV) of the AHI in the first 2 h of sleep for predicting an overall AHI > 15.

For predicting an overall AHI > 15, the sensitivity, specificity, PPV, and NPV of an AHI (AASM criteria) > 40 in the first 2 h were respectively: 0.304, 1.000, 1.000, and 0.335. For an AHI > 20 in the first 2 h, the corresponding values were 0.770, 0.962, 0.983, and 0.595. Corresponding values using CMS criteria were 0.347, 1.0, 1.0, and 0.6 for AHI > 40, and 0.693, 0.99, 0.986, and 0.76 for AHI > 20, respectively.

For justification of CPAP (overall AHI > 15), the sensitivity is slightly lower when using an AHI > 40 vs AHI > 20, but the specificity and PPV are much higher. Using AHI > 20 as criteria for SPL as opposed to the guideline criteria of AHI > 40 may be more effective in obtaining CPAP for patients with moderate to severe OSA.