Improved classification of dippers by individualized analysis of ambulatory blood pressure profiles

A decrease (dip) in blood pressure during sleep occurs in normal people and in patients with uncomplicated essential hypertension. Failure to identify such a dip suggests additional pathology, which makes the identification of "nondippers" important. Rigid definitions of nocturnal time periods (eg, night is defined as lasting from 22:01 to 06:00) to identify dippers and nondippers has been used for over a decade. However, these definitions may not correspond to actual sleep patterns, and thus may lead to faulty interpretations. We investigated whether or not an analysis of ambulatory blood pressure (BP) profiles according to the patients' individual reported awake/sleep pattern would result in an improved categorization of dippers and nondippers. Four groups of patients were investigated: normotensive volunteers, borderline hypertensive patients, essential hypertensive patients, and renal transplant recipients. In all four groups, blood pressure (systolic and diastolic) decreased to a greater degree when the individual reports were employed, compared to the fixed patterns. For systolic BP this difference (individualized v fixed 06:01 to 22:00 day and 22:01 to 06:00 night) amounted to 17.6 +/- 5.0 v 13.2 +/- 5.4 mm Hg for normotensive subjects, 18.5 +/- 6.0 v 11.7 +/- 8.6 mm Hg for borderline hypertensive subjects, 17.7 +/- 10.6 v 12.9 +/- 10.4 mm Hg for essential hypertensive patients, and 8.6 +/- 11.3 v 6.5 +/- 9.8 mm Hg in renal transplant patients (all P < .05). Individualized awake/sleep reports resulted in a better classification of dippers and nondippers, since misclassifications due to divergent sleep patterns (mainly going to bed late) were avoided.