Objectives:

Main objective: To assess the impact of obstructive sleep apnea (OSA) and its treatment on cardiovascular outcomes (morbidity and mortality) in patients with resistant hypertension (RH).

Secondary objectives: i) to identify the subclinical organ damage profile at baseline and its association with OSA, and to identify if long term blood pressure control and number of antihypertensive drugs needed is different depending on OSA diagnosis and its treatment; ii) to identify epigenetic profiles and clinical, biological and polygraphic variables with a predictive value for cardiovascular outcomes in RH patients with OSA; iii) to validate the HIPARCO-SCORE tool in men in an independent cohort and elaborate a new tool to be used in women; and iv) to perform a cost-effectiveness analysis to evaluate the impact of OSA diagnosis and treatment in patients with RH.

Methodology: Prospective cohort study. 1,371 RH patients will be recruited. Ambulatory blood pressure monitoring (ABPM), socio-demographic, clinical, OSA-related, biochemical and subclinical organ damage variables and biological samples at baseline will be collected from all the subjects included. A sleep study will be performed in all the subjects at the study inclusion date. Subsequently, the OSA subjects will be managed as per local standard practice. Follow-up variables will be annually collected (including blood samples). On the basis of OSA and its treatment, three cohorts of RH subjects will be defined: control (non-OSA), OSA-treated and OSA nontreated.

A minimum follow-up of 5 years has been established. During the follow-up, an annually programmed visit will be carried on to all patients, collecting variables from subjects' interview in the office.The baseline and follow-up variables will be collected using questionnaires.

The variables that will be collected are:

BP variables; Anthropometric variables; Compliance with CPAP in the case of CPAP-treated OSA patients; blood samples extraction; outcomes (heart disease, cerebrovascular disease, kidney disease, vascular disease). All the cardiovascular events will be independently evaluated by two doctors to establish a diagnostic. In case of discordance a third external doctor will assess the case. The date of each event will be recorded.

Inclusion Criteria:

• Patients diagnosed of RH according to the following criteria, which include 2 clinical situations: (i) BP above control in ABPM (24-h BP > 130/80 mmHg),regardless of optimal dose treatment with 3 agents (one must be a diuretic). Other causes of inadequate control must be discarded (poor compliance, drugs). (ii) Controlled BP but treated with no less than 4 medications.
• Patients aged 18 to 75 years old.
• To sign informed consent for the participation in the study.

Exclusion Criteria:

• Secondary hypertension to endocrinology causes (pheochromocytoma, Conn disease, Cushing´s Syndrome, hyperparathyroidism), drug treatment (NSAID or cortisone, immunodepressants, EPO), renal artery stenosis, alcohol abuse, aortic coarctation and intracranial tumours.
• Any process, that limits life expectancy to less than one year.
• Previously diagnosed OSA with current active treatment.

Patients with Resistant Hypertension