Abstract

Obstructive sleep apnea (OSA) and resistant hypertension (RH) are common interrelated conditions with high cardiovascular risk. There has been a close epidemiological association, but a thorough synthesis of the current findings on the nature of this relationship, effects of treatment, and clinical moderators has not been achieved. This systematic review was designed to critically evaluate recent evidence regarding the bidirectional relationship of OSA and RH and the epidemiology, pathophysiology, treatment outcomes, and clinical modifiers. In accordance with Preferred Reporting Items of Systematic Reviews and Meta-Analyses 2020, a systematic search was carried out between January 2021 and January 2026. Total twelve studies were included. The data support an effective bi-directional correlation, where a single study found that RH patients were at increased risk of incident OSA by 60%. OSA in RH also has a mechanistic relationship with certain end-organ damage involving left ventricular hypertrophy and deteriorating renal function. OSA treatment, mostly by continuous positive airway pressure, results in blood pressure reduction, especially nocturnal, but the benefits were found to be highly reliant on the most effective adherence, and most evident in severe or refractory phenotypes. The following critical clinical modifiers were discovered: insomnia and nasal obstruction were considered as powerful independent predictors of RH in OSA patients, and there is a sex-specific interaction; more severe OSA was found to be associated with refractory hypertension in men only. OSA and RH were synergistically associated, whereby OSA plays its role in causing treatment resistance and damage to the target organs.

Key words: Obstructive sleep apnea, resistant hypertension, refractory hypertension, continuous positive airway pressure, blood pressure, insomnia, systematic review