Home blood pressure measurement (HBPM) and ambulatory blood pressure measurement (ABPM) better predict cardiovascular events compared to office blood pressure, but differences exist between them. HBPM consists of active manual readings and could exert an anxiety response, in contrast to automated readings with ABPM. We studied the prevalence and reproducibility of incremental differences between HBPM and daytime ABPM in subjects referred for out-of-the-office blood pressure measurement and assessed their relation with anxiety and hypertensive organ damage.Design and method:
A total of 176 subjects, aged 57.1 ± 12.8, 43.2% female were included. All subjects underwent two weeks of morning and evening HBPM with a 24-hour blood pressure recording in between. Anxiety trait and state were assessed using VAS and STAI anxiety scales. Microalbuminuria and microalbumin to creatinine ratio (MCR) were used to assess hypertensive organ damage. Incremental thresholds of = > 10/5 and = > 20/10 mmHg were used to define relevant differences between HBPM and daytime ABPM.Results:
A total of 92 (52.3%) subjects showed a => 10/5 mmHg difference between HBPM and daytime ABPM, whereas 35 (19.1%) had a difference => 20/10 mmHg. Patients with incremental blood pressure differences were older, had a higher BMI, higher office blood pressure and lower glomerular filtration rate (p < 0.01). Incremental differences between HBPM and daytime ABPM were highly reproducible (r = 0.800 for systolic and 0.669 for diastolic blood pressure, p < 0.001). While both systolic HBPM and daytime ABPM were correlated with microalbuminuria (p = 0.027 and 0.035) and MCR (p = 0.009 and 0.052), no association was found between incremental blood pressure differences and hypertensive organ damage (p = 0.898 for microalbuminuria and 0.414 for MCR). There was no association with either anxiety trait or state.Conclusions:
Clinically meaningful differences between HBPM and daytime ABPM are common and highly reproducible. Incremental differences between home and ambulatory blood pressure were not correlated with anxiety trait or state, nor with the prevalence of hypertensive organ damage. Our results suggest that an ‘auto-cuff’ response during HBPM shares resemblance with the white coat effect, being an apparently benign condition. Our results may have implications for the interpretation of differences between HBPM and ABPM in clinical practice.