Difference between apnea-hypopnea index (AHI) and oxygen desaturation index (ODI): proportional increase associated with degree of obesity
Obesity is one of the main predisposing factors for obstructive sleep apnea (OSA) hypopnea syndrome. It has been described that body mass index (BMI) influences the accuracy of oxygen desaturation index (ODI) for the diagnosis of OSA by polysomnography (PSG). We analyzed the relationship between traditional indicators: apnea-hypopnea index (AHI) and ODI in a population at high risk for OSA, by respiratory polygraphy (RP) and PSG.
This is a retrospective study of 1898 patients with suspicion of OSA, from which 1053 underwent RP and 582 underwent PSG with OSA. We compared results considering gender, age, and degree of obesity.
This study included 1333 records of patients with OSA—more than 80 % of whom were overweight or obese. We observed that AHI and ODI increased progressively with obesity grade and said increase was associated with BMI only in men. The evaluation of the agreement between AHI and ODI found a difference between normal weight and obese patients, regardless of gender.
Study findings contribute to understand the role of oximetry in the diagnosis of OSA in obese patients. Our results were observed using full PSG and a simplified home method. The correlation between these indicators could improve our clinical interpretation of OSA severity among obese patients when abbreviated tests are used.
KeywordsObesity Obstructive sleep apnea Respiratory polygraphy Polysomonography
Compliance with ethical standards
No funding was received for this research.
Conflict of interest
The authors declare that they have no conflict of interest.
All procedures performed in this study were in accordance with the ethical standards of the Hospital Británico de Buenos Aires and Hospital Alemán committees and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
Informed consent was obtained from all individual participants included in the study.
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