Comparative Analysis of Diagnostic Methods in Obstructive Sleep Apnea Syndrome: Polysomnography and Use Watch PAT 200

Abstract

Objectives:

Obstructive sleep apnea syndrome (OSAS) is a public health problem in terms of its impact on quality of life and increased risk of cardiovascular disease. One of the few national epidemiological studies was published and showed a prevalence of 32.8% of OSA in the population of Sao Paulo. The gold standard for diagnosis of OSA is polysomnography (PSG). Despite this, tests often show the same individual variability and inter night to night. Because it is costly and time consuming, other diagnostic tools such as the Watch PAT 200 (WP) were developed. This is an ambulatory device that consists of a actgraphy, sensors capturing peripheral arterial tonometry (PAT) and body position, pulse oximetry, and microphone to capture snoring.

Objectives:

Evaluate the difference between two diagnostic methods for OSAS: PSG and WP.

Methods:

A study in the sleep laboratory of the Complexo Hospitalar Edmundo Vasconcelos from June to August 2012, including 20 volunteers who had no exclusion criteria and performed using the same night of PSG and WP 200,interpreted by two different examiners.

Results:

20 patients, 70% male and 30% female, mean age 37.1 years (standard deviation - SD ± 12.1), mean BMI 29.1 (SD ± 5.2), and Epworth average score of 11.9 (SD ± 3.1). There was agreement among examiners quantitative bias of PSG with average DP of 9.7 and -2.9, between the WP and the mean AHI of examiners was average bias of 3.2 and SD of 8.8. There was qualitative agreement between examiners. PSG AHI was classified in the same category by the two examiners in 13 (65%) between the average of PSG and WP no agreement in 13 subjects (65%). Accuracy of WP as a screening test for OSA, using PSG as the gold standard, the WP showed 100% sensitivity for the diagnosis of OSA (AHI 5), specificity 33.3%, positive predictive value of 89.4% and negative predictive value 100% for OSA.

Conclusions:

AHI agreement between WP and PSG was good. Being sensitive and 100% negative predictive value for the diagnosis of OSA (AHI 5) are ideal characteristics for a screening test.