Number and timing of ambulatory blood pressure monitoring measurements

Ambulatory blood pressure (BP) monitoring (ABPM) may cause sleep disturbances. Some home BP monitoring (HBPM) devices obtain a limited number of BP readings during sleep and may be preferred to ABPM. It is unclear how closely a few BP readings approximate a full night of ABPM. We used data from the Jackson Heart (N = 621) and Coronary Artery Risk Development in Young Adults (N = 458) studies to evaluate 74 sampling approaches to estimate BP during sleep. We sampled two to four BP measurements at specific times from a full night of ABPM and computed chance-corrected agreement (i.e., kappa) of nocturnal hypertension (i.e., mean asleep systolic BP ≥ 120 mmHg or diastolic BP ≥ 70 mmHg) defined using the full night of ABPM and subsets of BP readings. Measuring BP at 2, 3, and 4 h after falling asleep, an approach applied by some HBPM devices obtained a kappa of 0.81 (95% confidence interval [CI]: 0.78, 0.85). The highest kappa was obtained by measuring BP at 1, 2, 4, and 5 h after falling asleep: 0.84 (95% CI: 0.81, 0.87). In conclusion, measuring BP three or four times during sleep may have high agreement with nocturnal hypertension status based on a full night of ABPM.