Prognostic value of blood pressure circadian rhythm disturbances in normotensive shift workers of the Arctic polar region
Objective. To study chronophysiological alterations in blood pressure (BP) rhythms in normotensive patients and define their prognostic value in development of arterial hypertension (HTN) in shift workers at the Arctic Polar region in a prospective (one-year) observation. Design and methods. We examined 173 men with normal BP and without HTN (mean age: 40,2 ± 4,1 years; mean northern shift-work experience: 16,5 ± 6,8 years; mean length of service: 11,2 ± 3,8 years and mean office systolic/diastolic BP 123,4 ± 7,5 / 80,5 ± 5,5 mmHg) within one-year prospective study during shift work in the Arctic region (monthly roundabouts to Arctic region and back to home cities). All patients underwent ambulatory BP monitoring (ABPM) with consequent chronobiologic data analyses once every 3 months. Results. One-year prospective study of chronobiological parameters showed a high prevalence of distinct atypical types of BP diurnal rhythms/variability disorders in normotensive persons staying in the Far North. Moreover, preexisting BP variability/rhythm disorders have high prognostic value and are associated with high risk of HTN development within one year. Also, atypical normotensive BP variants were characterized by more evident structural cardiovascular changes. Moreover, chronobiological approach showed higher diagnostic sensitivity, specificity and efficiency in comparison with conventional analysis of ABPM. Conclusions. Logistic regression showed prognostic significance of normotensive atypical rhythm/variability disorders compared to the conventional risk factors (smoking, low physical activity, body mass index, dyslipidemia, age, duration of stay in the North and camp experience, the mode and type of shift schedule). By multivariate analysis we developed a model for the risk prediction of HTN development during the year in normotensive people working as shiftworkers in the Far North.