Reproducibility of daytime hypertension, night-time hypertension, and nocturnal blood pressure dipping patterns in young to middle age patients with stage 1 hypertension

Objective: To investigate the reproducibility of ambulatory BP sub-periods and nocturnal dipping phenotypes assessed twice 3 months apart in young-to-middle-age untreated individuals screened for stage 1 hypertension. Design and methods: We investigated 1096, 18-to-45-year old participants from the HARVEST. Their office BP was 145.8 ± 10.4/93.7 ± 5.7 mmHg. Office BP and 24 h BP were measured at baseline and after 3 months. Office, 24-h, daytime and night-time hypertensions, and nocturnal dipping patterns were defined according to the 2023 ESH guidelines. Between-recording agreement was evaluated with kappa statistics. Results: Reproducibility evaluated with weighted kappa was moderate for both 24 h hypertension (K = 0.48) and daytime hypertension (K = 0.50) and was only fair for night-time hypertension (K = 0.36). Between-measurement agreement was even worse for isolated night-time hypertension (K = 0.24), and was poor for office hypertension (K = 0.14). The better reproducibility of daytime than night-time period was confirmed by the analysis of BP as continuous variable (all between-period differences, P < 0.001). Nondipping was present in 31.8%, and showed a fair agreement (K = 0.28,). Poorer agreement was shown by extreme dipping (K = 0.18) and reverse dipping (K = 0.07). Conclusions: These data show that within the ambulatory sub-periods, daytime hypertension has a better reproducibility than night-time hypertension. This suggests that the better association with adverse outcomes shown by sleep BP compared to wake BP in observational studies is not due to a better reproducibility of the former. The between-measurement agreement is even worse for isolated nocturnal hypertension and dipping patterns, especially for extreme and reverse dipping. Thus, these BP phenotypes should be confirmed with repeat ambulatory BP monitoring.