The pathophysiological overlap between primary aldosteronism (PA) and obstructive sleep apnea (OSA) has been suggested. Therefore in an on-going prospective OSA-PA study we have evaluated the frequency of PA in patients suspected of OSA.Design and method:
We included 139 consecutive hypertensive patients (mean age 53.6 ± 12.0 years, 86 M, 53F) referred for polysomnography (PSG) on the basis of one or more of the following clinical features suggestive for OSA: typical symptoms, resistant or difficult-to-treat HT and comorbidities known to be associated with OSA and high cardiovascular risk. Clinically important moderate-to-severe OSA was diagnosed if the apnea/hypopnea index (AHI) was > 15 events/h. PA was diagnosed if the the salt infusion test (SIT) was abnormal (postinfusion plasma aldosterone levels >10ng/dl). Age, gender, neck circumference, office blood pressure levels, presence of metabolic syndrome (MS) and its components (abdominal obesity, glucose metabolism alterations [increased fasting glucose or diabetes], increased triglycerides, decreased HDL cholesterol levels), known cardiovascular disease (CVD) as well as OSA symptoms: presence of snoring, nycturia and daytime somnolence (evaluated by Epworth Sleepiness Scale – ESS) were recorded.Results:
The group of hypertensive patients referred for PSG was characterized by resistant hypertension (44.6%), abdominal obesity (79.9%) and MS (78.4%). OSA was diagnosed in 67 patients (48.2% of the whole group). PA was diagnosed in 11 patients with OSA (16.4%) as compared to 6 patients in the group without OSA (8.3%; p = 0.12). Among patients with moderate-to-severe OSA there were no differences in age, gender, blood pressure levels, frequency of MS and its components, frequency of resistant hypertension, CVD and OSA symptoms between patients with PA and without PA. In the whole evaluated group, patients with PA as compared to patients without PA were characterized by higher rate of resistant hypertension (70.6 vs 41.0%; p = 0.021), glucose metabolism alterations (82.4 vs 57.6%; p = 0.051) and metabolic syndrome (100 vs 75.2%; p = 0.020). Those conditions were also more frequent in patients with OSA as compared to patients without OSA.Conclusions:
Preliminary results of this on-going study suggest that the prevalence of PA in hypertensive patients with moderate-to-severe OSA is 16%.