Sex-specific associations between erythrocyte measures and obstructive sleep apnea

Study Objectives: Hypoxemic effects of obstructive sleep apnea (OSA) have been implicated in changes in erythropoiesis and hence erythrocyte measures. Sex differences are evident in both OSA and erythropoiesis. Whether sex modulates the relationship between severity of OSA and erythrocyte measures has not previously been studied. Methods: We examined a sample of 976 patients (38% women) who underwent overnight polysomnography and measurement of red blood cell count, hemoglobin, and hematocrit. Patients were divided into primary snoring and mild, moderate, and severe OSA groups, separately by sex. Results: In multiple regressionmodels, we found significant interactions between sex and oxygen desaturation index and apnea-hypopnea index on erythrocyte measures. Higher oxygen desaturation index and higher apnea-hypopnea index were independently associated with higher red blood cell count, hemoglobin, and hematocrit in women but not in men. Further ordinal logistic regression analysis showed a significant association between oxygen desaturation index (odds ratio, 2.33; 95% confidence interval, 1.17-4.66) and apnea-hypopnea index (odds ratio, 2.44; 95%confidence interval, 1.23-4.84) and red blood cell count in women only. Correlation analysis also showed that erythrocyte measures and markers of cardiometabolic risk were more closely correlated in women than in men. Conclusions: This study provides novel data suggesting a significant association between erythrocyte measures and OSA severity in women but not in men. Similarly, the relationship between hematologic metrics and cardiometabolic risk markers was more pronounced in women than in men. Our findings suggest a sex-specific impact of OSA on erythrocyte measures and on their relationship with indexes of cardiometabolic risk.