INTRODUCTION: Determination of clinical obstructive sleep apnea syndrome (OSAS) types is important for treatment decision. In the literature, there are two different criteria for the diagnosis of position and rapid eye movement (REM) related OSAS. One of them provides the criteria that nonsupine and/or non-REM apnea-hypopnea index (AHI) below 5, the other does not. In this study, these two definitions are named as “strict definition” and “loose definition.” This study is designed to identify which definition is more beneficial to use, and the prognostic value of the definitions by using OSAS severity according to AHI. This is the first study which investigates those issues.
MATERIALS AND METHODS: This study is a retrospective cohort study. Obstructive AHI >5 of all adult patients admitted to our sleep disorders center between September 2012 and October 2014 were included to this study. The patients were grouped due to both strict and loose definitions. Patient groups were named as position related, REM related, REM + position related, pure OSAS due to loose definitions, and position dependent, aggravated by position, REM dependent, aggravated by REM, REM + position dependent, aggravated by REM + position, pure OSAS due to strict definitions. All these groups were compared for demographic and polysomnographic parameters.
RESULTS: Two hundred and eighty (73.7%) of the patients were male, 100 (26.3%) were female, with a mean age of 49.9 ± 11.6, body mass index of 30.4 ± 5 and neck circumference of 43.2 ± 4.2. The patients had a mean Epworth Sleepiness Scale score: 13.5 ± 7, mean AHI: 32.3 ± 25.4, mean arousal index: 27.1 ± 19.6, mean peripheral capillary oxygen saturation (SpO2): 90.6 ± 4, and mean minimum SpO2: 78.7 ± 9.8. In OSAS aggravated by REM, position, REM + position total AHI, apnea index, hypopnea index, minimum SpO2 and desaturation percentage were all found significantly worse than REM dependent, position-dependent and REM + position-dependent OSAS patients (P < 0.05).
CONCLUSION: In light of current findings, when evaluated with their effect on disease severity and complications, it is useful to predict prognosis of the disease when “strict definitions” are used for position- and/or REM-related OSAS cases.