Sex differences in ambulatory blood pressure monitoring

PURPOSE: Referral to ambulatory blood pressure monitoring may have bearing upon blood pressure control and prognosis. We describe sex-related differences in referral for ambulatory monitoring and their prognostic impact. METHODS: Between 1991 and 2005, 3957 patients were monitored in our ambulatory monitoring service, of whom 2114 (53%) were women. Demographic and clinical data were analyzed according to sex. RESULTS: Age (58 +/- 15 vs 52 +/- 17 years, respectively) and body mass index (27.5 +/- 4.9 vs 26.9 +/- 4.0 kg/m(2), respectively) were higher in women than men. Treatment for hypertension was more prevalent in women (62% vs 53%, respectively). Clinic systolic blood pressure (148 +/- 24 vs 146 +/- 20 mm Hg, respectively) and clinic pulse pressure (65 +/- 22 vs 59 +/- 18 mm Hg, respectively) were higher in women compared with men. In women, the white-coat effect was increased, compared with men; 5.2 +/- 12.4% vs 1.5 +/- 10.7% systolic, and 5.4 +/- 11.2% vs 3.6 +/- 10.3% diastolic. Consequently, women had lower ambulatory blood pressure than men. In women, 24-hour blood pressure was 136 +/- 17/76 +/- 10 vs 140 +/- 15/81 +/- 10 mm Hg in men, awake blood pressure 141 +/- 17/80 +/- 11 vs 144 +/- 15/84 +/- 10 mm Hg, and sleep blood pressure was 125 +/- 19/67 +/- 10 vs 127 +/- 18/71 +/- 11 mm Hg. Age-adjusted ambulatory blood pressure also was lower in women. Ambulatory heart rate was higher in women (P < .0001). Kaplan-Meier survival did not differ by sex (P = .66), despite older age and higher clinic blood pressure. CONCLUSIONS: The results might imply that referral was driven by the physicians' overall patient risk perception. The greater magnitude of white-coat effect in women, and correspondingly lower ambulatory blood pressure, might in part account for similar mortality in the face of older age and higher clinic blood pressure. (C) 2008 Elsevier Inc. All rights reserved.