Blood pressure, cardiac structure and severity of obstructive sleep apnea in a sleep clinic population

Objectives We investigated whether the severity of obstructive sleep apnea (OSA) predicts blood pressure or cardiac left ventricular thickness in a cl inical population of OSA patients, if adjustments are made for age, gender, use of antihypertensive agents, smoking, body mass index, history of coron ary artery disease, hypercholesterolemia and circulating C-peptide concentr ations. Design Relationships in this cross-sectional study were investigated with c orrelation analysis and multiple regression procedures. Patients and methods Apnea-hypopnea index (AHI, polysomnography) and office systolic and diastolic blood pressures (SBP and DBP) were measured in 81 s ubjects referred to a university hospital sleep laboratory. Ambulatory bloo d pressures were recorded during one 24 h cycle. Left ventricular (LV) musc le size was quantified as two-dimensionally directed M-mode-derived end-dia stolic thickness of interventricular septum and posterior chamber wall. Results After adjustment for separate or the entire set of covariates, AHI predicted office SBP and DBP as well as daytime ambulatory DBP and night-ti me ambulatory SBP and DBP, but not daytime ambulatory SBP. In contrast, ass ociations between AHI and LV muscle thickness reflected complex inter-relat ionships with confounding variables. Smoking and age suppressed, whereas bo dy mass index (BMI) and hypertension inflated the relationship between OSA severity and LV muscle thickness in this study. Conclusions AHI is an independent predictor of several measures of blood pr essure. OSA severity and LV muscle thickness appear to be primarily linked via increased blood pressure. (C) 2001 Lippincott Williams & Wilkins.