Evidence from longitudinal studies has reported contradictory results regarding the association between obstructive sleep apnea (OSA) and hypertension. In a previous analysis of the Vitoria Sleep Cohort, we evaluated the relationship between OSA and the risk of developing hypertension and we did not find an independent association after adjustment for confounding factors. In the present study, we perform a post hoc analysis to assess the association between OSA and incident stage 2 hypertension (systolic blood pressure ≥ 160 mmHg and/or diastolic blood pressure ≥ 100 mmHg) based on gender differences.
A prospective study was performed over 7.5 ± 0.8 years on a middle-aged general population, which included 1,155 normotensive subjects (43.7% men) who completed the follow-up. Blood pressure measurements (at baseline and follow up) and polygraphy at baseline were performed. Logistic regression models were used to determine the association between the respiratory disturbance index (RDI) and stage 2 hypertension and a recursive partitioning method was used to determine the variables related to the incidence of stage 2 hypertension. The RDI was divided into subgroups (0-2.9, 3-6.9, 7-13.9 and ≥14), using the first subgroup as reference.
For men, an RDI ≥ 14 was associated with a significantly increased odds ratio (OR) for stage 2 hypertension [OR = 2.54 (95% CI 1.09-5.95), p = 0.032]. This association was not statistically significant among women (p = 0.371).
Our results suggest an association between moderate to severe OSA and the incidence of more severe forms of hypertension in men but not in women. However, as this is a community-based study, our women’s population characteristics may differ from women usually seen in sleep-disorders clinics.