Aims: Sleep apnoea has significant medical implications. A reliable non-invasive method (as a regular Holter system with a specific software) would be valuable for the screening of this condition in ambulatory patients.
Methods and results: A total of 40 patients were divided into two groups: Group I, 20 patients with clinical suspicion of obstructive sleep apnoea (OSA) and Epworth sleepiness score >or= 10 and Group II, 20 controls. In Group I, polysomnography was performed simultaneously with Holter (specific software to detect sleep apnoea). In Group II, Holter-based detection was utilized. A cutoff value of 10 for the apnoea-hypopnoea index (for polysomnography) or for the respiratory disturbance index (RDI) (for Holter) was considered abnormal. Sleep apnoea was confirmed by polysomnography in 14 patients (70%) in Group I. Holter recordings correctly identified OSA in 11 patients (r = 0.74 with polysomnography; P = 0.0002). Holter showed 78.5% sensitivity, 83.3% specificity, 91.6% positive predictive value, and 62.5% negative predictive value (with polysomnography as the gold standard). The RDI measured by Holter was 19.5 +/- 20 in Group I and 3.9 +/- 4.4 in controls (P < 0.005). The measurement between Holter and polysomnography (Bland and Altman method) showed good correlation (mean 4.7 with 39.4 and -30.1 SD) and a Pearson correlation coefficient (r) of 0.74 (P = 0.0002, 95% CI: 0.44-0.89).
Conclusion: Holter-based software may constitute an accessible tool on initial suspicion of OSA.