Severity of individual obstruction events is gender dependent in sleep apnea

Purpose In obstructive sleep apnea (OSA), severity of individual obstruction events is connected to increased mortality rate and it can be significantly different in patients with similar apnea-hypopnea index (AHI). However, possible gender-dependent variation in severity of obstruction events in different OSA categories is unknown. We investigated whether the severity of obstruction events differs between genders with similar AHI and if this difference varies between OSA categories. Methods Polygraphic recordings of 2057 consecutive patients with suspected OSA were reanalyzed and those with AHI ≥5/h were included for further analysis (nmale = 893 and nfemale = 197). Statistical significance of differences in AHI, apnea index, hypopnea index, oxygen desaturation index, obstruction severity parameter, and severity of individual obstruction events between genders were evaluated using the Mann-Whitney U (MWU) test as well as the general linear model (GLM) univariate analysis adjusted for age, BMI, smoking, daytime sleepiness, snoring, and heart failure. Results Apneas were 16.9 and 19.6% longer (MWU p ≤ 0.015, GLM p ≤ 0.036) and desaturation areas were 15.4 and 23.7% larger (MWU p ≤ 0.024, GLM p ≤ 0.053) in males compared to females with moderate and severe OSA, respectively. In contrast, hypopneas were 9.1% shorter (MWU p = 0.001, GLM p ≤ 0.001) and desaturation areas were 6.0% smaller (MWU p = 0.114, GLM p = 0.025) in men with mild OSA. The apnea index was 433.3 and 313.1% higher (MWU p ≤ 0.001, GLM p ≤ 0.043) and the hypopnea index was 12.2 and 17.8% lower (MWU p ≤ 0.001, GLM p = 0.002, p = 0.083) in males with mild and moderate OSA, respectively. Conclusion As severity of individual obstruction events was significantly different in males and females, the overall severity of OSA may not be similar despite the similarity in AHI.