Chest
Volume 135, Issue 2, February 2009, Pages 330-336
Journal home page for Chest

Original Research
Sleep Medicine
Diagnosis of Obstructive Sleep Apnea Syndrome and Its Outcomes With Home Portable Monitoring

https://doi.org/10.1378/chest.08-1859Get rights and content

Background

The use of portable respiratory monitoring (PM) has been proposed for the diagnosis of obstructive sleep apnea syndrome (OSAS), but most studies that validate PM accuracy have not followed the best standards for diagnostic test validation. The objective of the present study was to evaluate the accuracy of PM performed at home to diagnose OSAS and its outcomes after first validating PM in the laboratory setting by comparing it to polysomnography (PSG).

Methods

Patients with suspected OSAS were submitted, in random order, to PM at the sleep laboratory concurrently with PSG (lab-PM) or at home-PM. The diagnostic performance was assessed by sensitivity, specificity, positive and negative predictive values, positive likelihood ratio (+LR), negative likelihood ratio (−LR), intraclass correlation coefficients, κ statistic, and Bland-Altman plot.

Results

One hundred fifty-seven subjects (73% men, mean age ± SD, 45 ± 12 yr) with an apnea-hypopnea index (AHI) of 31 (SD ± 29) events/h were studied. Excluding inadequate recordings, 149 valid comparisons with lab-PM and 121 with unattended home-PM were obtained. Compared to PSG for detecting AHI > 5, the lab-PM demonstrated sensitivity of 95.3%, specificity of 75%, +LR of 3.8, and −LR of 0.11; the home-PM exhibited sensitivity of 96%, specificity of 64%, +LR of 2.7, and −LR of 0.05. Kappa statistics indicated substantial correlation between PSG and PM results. Bland-Altman plot showed smaller dispersion for lab-PM than for home-PM. Pearson product moment correlation coefficients among the three AHIs and clinical outcomes were similar, denoting comparable diagnostic ability.

Conclusions

This study used all available comparison methods to demonstrate accuracy of PM in-home recordings similar to that of repeated PSGs. PM increases the possibility of correctly diagnosing and effectively treating OSAS in populations worldwide.

Section snippets

Research Subjects

Consecutive patients > 18 years of age who were referred for evaluation of suspected OSAS were invited to participate in the study if they signed the informed consent form. Pregnant women, patients with severe comorbidities (cancer, heart failure, etc) or difficulties that would interfere with the examinations, and patients residing outside the metropolitan area of Porto Alegre (Rio Grande do Sul, Brazil) were excluded. This study was approved by the Ethics Committee of our institution.

Study Protocol

The

Results

Two hundred and twenty patients were invited to participate in the study between November 2004 and August 2006. One hundred and sixty-three consented, and 157 underwent PSG and were included in the analysis. Figure 1 shows a diagram of the subject recruitment flow. The 57 patients who did not consent to participate in the study were similar to the analyzed population in terms of age, gender, body mass index (BMI), and BP.

Data from the lab-PM were lost for eight (6%) subjects as follows: six had

Discussion

In this study, a type 3 PM was tested for its ability to diagnose OSAS at home and was simultaneously validated against the laboratory “gold standard” in a large sample of patients with clinically suspected OSAS, which represents the spectrum seen in clinical practice. The order of the examinations done in the laboratory or at home was randomly assigned. The results show that the accuracy of home-PM compared with PSG is within the limits usually seen when two diagnostic tools are compared. Our

Conclusions

After being validated at the laboratory against full PSG, the diagnostic performance of a type 3 PM for detecting OSAS at home is within acceptable limits for diagnostic tests. The agreement of home-PM with PSG is similar to that described between two typical PSG studies. These results suggest that the availability of PM will increase the possibility of correctly diagnosing and effectively treating sleep breathing disorders in populations worldwide.

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    Financial support was granted by the Brazilian government through a research incentive fund (FIPE) of the Hospital de Clinicas de Porto Alegre.

    No conflict of interest exists for any of the authors.

    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/misc/reprints.shtml).

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