Synergistic effect of anemia and obstructive sleep apnea on hypertension: National Health and Nutrition Examination Survey 2015–2018

Objective: Anemia, obstructive sleep apnea (OSA), and hypertension are common social health problems. They are interconnected. This study assessed the independent association of anemia and OSA with hypertension and the interaction between anemia and OSA on hypertension in the US population. Methods: Data used by this retrospective study were obtained from the National Health and Nutrition Examination Survey (NHANES) 2015–2018. The relative excess risk due to interaction (RERI), weighted logistic regression, and the attributable proportion due to interaction (AP) were used to investigate the interaction above. Its impact was also assessed via subgroup analysis by gender, age, race, diabetes, smoking, alcohol use, education, and marital status. Results: After covariate adjustment in 6949 eligible observers, it was found that compared with non-OSA patients, OSA patients were at higher risk of hypertension [odds ratio (OR) = 1.254, 95% confidence interval (CI) 1.099–1.432, P < 0.001). Meanwhile, OSA and anemia had a potential synergistic effect on the incidence of the disease (OR = 1.705, 95% CI: 1.390–2.091, P < 0.01): the RERI was 0.371, and the AP was 0.218. In addition, such effect was observed in the subgroup of other race (AP = 0.48), the nondrinking subgroup (AP = 2.50), the subgroup graduating from high school or above (AP = 0.28), the unmarried subgroup (AP = 0.4), the subgroup without diabetes (AP = 0.24), and the drinking subgroup (AP = 0.41). Conclusion: Anemia and OSA had a potential synergistic effect on hypertension. Their relationship needs to be further elucidated by a further study.