Accuracy of Type III Portable Monitors for Diagnosing Obstructive Sleep Apnea

OBJECTIVES: We evaluated whether the results from portable monitor (PM) devices for the diagnosis of obstructive sleep apnea (OSA), classified into type III and type IV devices by the American Academy of Sleep Medicine, correlated with the results from polysomnography (PSG) testing. METHODS: Sixty-four patients with a sleep-breathing disorder used type III or type IV PM devices at home and were subsequently admitted for testing using PSG. The apnea-hypopnea index (AHI) from each machine was measured, and the AHI component, apnea index (AI), and hypopnea index (HI) were also analyzed. RESULTS: There was a stronger correlation between the AHI values from PSG testing and those from the type III PM devices (r = 0.92, p < 0.001) than for the data from type IV devices (r = 0.69, p < 0.001). However, the correlation of HI values (type III: r = 0.43, p = 0.024; type IV: r = 0.14, p = 0.41) was poorer than that of the AI values (type III: r = 0.95, p < 0.001; type IV: r = 0.68, p < 0.001). Moreover, the type III PM devices tended to evaluate a patient's condition as less severe than did PSG testing when the AHI value was over 30. CONCLUSIONS: Although type III PM devices outperformed type IV devices as substitutes for PSG, the clinical state must be evaluated for patients suspected of having obstructive sleep apnea.