Home Portable Sleep Testing Has Gone Global

Journal of Clinical Sleep Medicine, Vol. 12, No. 1, 2016 In an effort to decrease wait times, decrease expense and expedite institution of therapy for obstructive sleep apnea (OSA), home sleep testing (HST) has become increasingly more popular since the 2007 AASM clinical guidelines on home portable monitoring.1 The term HST is not entirely accurate, as these devices do not measure sleep. They are respiratory monitors applied to the patient during the estimated sleep time. The term sleep apnea testing is preferred as this is geared towards establishing the diagnosis of OSA. Regardless, the HST is easy to perform and can be done in the comfort of the patient’s home environment. HST throughout the world has shown a good sensitivity and specificity for detecting OSA for patients with a high pretest probability.2 Scoring of these studies may be performed by computer only, computer assisted with manual oversight or by a trained specialist. Scoring criteria have been established by the AASM,3 but comparison of these criteria internationally has been limited. Magalang et al. examine the agreement between independent scorers in six countries using AASM scoring criteria from 2007.3–5 The initial studies were performed in a single center and then reviewed at different institutions. Apnea hypopnea index (AHI) had a strong correlation when scoring was performed from nasal pressure (NP) recordings. Hypopneas were more easily recognized from the transformed NP tracing, which has been previously demonstrated.6 NP and transformed NP tracings performed better than respiratory induction plethysmography (RIP) in the detection of apneas. The detection of central apneas had less sensitivity and specificity, however transformed NP waveform was superior to NP and RIP analysis for central apnea identification. Respiratory inductive plethysmography (RIP) waveform analysis was less effective for identification of apneas, probably because it is not calibrated in clinical practice. Even when calibrated, RIP may erroneously classify events as central since it does not detect respiratory effort in up to 9% of patients.7 Clinical interpretation of HST is at times troublesome because of recognition of sleep onset and offset as well as recognition of artifacts. Editing the data manually improves the accuracy of the study interpretation.8 These variables were appropriately excluded from this study since the aim was the analysis of the scored respiratory events. In practice, COMMENTARY