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The variability of the apnoea–hypopnoea index
Author(s) -
Bittencourt Lia Rita Azeredo,
Suchecki Deborah,
Tufik Sergio,
Peres Clóvis,
Togeiro Sônia Maria,
Bagnato Maurício Da Cunha,
Nery Luiz Eduardo
Publication year - 2001
Publication title -
journal of sleep research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.297
H-Index - 117
eISSN - 1365-2869
pISSN - 0962-1105
DOI - 10.1046/j.1365-2869.2001.00255.x
Subject(s) - supine position , medicine , intraclass correlation , polysomnography , body position , coefficient of variation , anesthesia , apnea , physical medicine and rehabilitation , mathematics , statistics , clinical psychology , psychometrics
This study was designed to evaluate the variability of the apnoea–hypopnoea index (AHI) in 20 patients with obstructive sleep apnoea–hypopnoea syndrome (OSAHS) and to determine possible relationships of this variability with other polysomnographic parameters. The subjects were recorded on four consecutive nights. The mean AHI values were not significantly altered throughout the four recording nights ( P =0.67). The intraclass correlation coefficient of the AHI on the four nights was 0.92. However, the Bland and Altman plot showed that, individually, the AHI presented an important variability, which was not related to its initial value. In regard to the OSAHS severity, 50% of the patients changed the classification from the first to the subsequent nights. Thirteen of the 20 patients (65%) presented a variation in the AHI value equal or higher than 10 events h –1 . When we evaluated the AHI mean values for a specific body position and sleep stage, no difference was observed among the nights. In both supine and lateral–ventral decubitus, higher AHI was observed during Stages 1 and 2 than the other stages. Additionally, the AHI during Stages 1 and 2 and REM sleep was higher on the supine than on the lateral–ventral decubitus. The AHI in OSAHS patients presented a good correlation among the four recording nights; however, a significant individual variability should be considered, especially when AHI is applied in OSAHS classification or as a criterion of therapeutic success.