A 25-year longitudinal study on dipping/nondipping tracking in the general population: the PAMELA study

Background: The long-term reproducibility of the nighttime blood pressure (BP) phenotypes, namely, dipping (D) and nondipping (ND) has never been described in population-based studies. We investigated this issue in the participants to the third survey of PAMELA study in which clinical, laboratory, ambulatory BP monitoring (ABPM) and target organ damage data were prospectively collected over a 25-year period. Methods: A total of 541 participants who attended the initial survey and two subsequent ones, 10 and 25 years later, were included in the analysis. ND pattern was defined as a night-time reduction in systolic BP lower than 10% compared to day-time values. Results: During the 25 years of follow-up, 201 of the 541 participants (37.15%) with D pattern at entry maintained the same circadian BP profile in the two subsequent visits 10 and 25 years later (i.e. persistent D pattern). The corresponding rate of participants with ND pattern at the initial observation and confirmed at both subsequent data collection was about six times lower (i.e. 5.7%). No difference was found in cardiac and vascular end-organ damage markers among participants with prevalent (2 of 3) and persistent ND phenotype compared with their counterparts with occasional ND (1 of 3) and persistent D, after adjustment for conventional risk factors. Conclusions: Our results suggest that nocturnal BP phenotypes are poorly reproducible. In particular the detection of fully reproducible ND pattern over the course of a quarter of a century involves just a minute fraction of the entire cohort. We failed to find an association of persistent vs. occasional nighttime BP phenotypes with target organ damage and this important issue requires to be further investigated in larger studies.