Seasonal variability of blood pressure (BP) in the population has been actively studied for more than two decades. However, individual seasonal fluctuations in blood pressure and, in particular, their prognostic significance have not been adequately studied.
PURPOSE OF THE STUDY
To study seasonal changes in individual levels of clinical and 24-hour blood pressure and their prognostic value in patients with arterial hypertension (AH) in two regions of the Russian Federation (Ivanovo and Saratov).
MATERIAL AND METHODS
A cohort prospective study was carried out. Patients who applied for an outpatient appointment with a GP, cardiologist, or who were registered in outpatient clinics for various reasons, were included in the study in summer (June-August) and winter (December-February). Two visits were envisaged with an interval of 6 months ± 7 days. During each visit, a standard survey, anthropometry, measurement of blood pressure with an automatic tonometer, and 24-hour blood pressure monitoring (ABPM) (stage 1) were performed. At the 2nd stage, information about the end points was collected. The average follow-up period was 6.4±0.1 years. The primary combined endpoint included death, myocardial infarction, cerebral stroke, development of heart failure, and other cardiovascular complications.
RESULTS:
Both planned visits were attended by 770 patients: 499 in Ivanovo (average age 52±10 years, men 36.3%) and 269 in Saratov (average age 58±11 years, men 56.1%). An individual analysis revealed a significant «spread» of indicators of seasonal dynamics of blood pressure. In 34% of patients, winter clinical systolic blood pressure (SBP) exceeded the corresponding summer rate by more than 10 mm Hg. A fully opposite picture was observed in 14% of patients. The results of ABPM gave a slightly more even separation of patients compared to clinical BP. Information on endpoints and vital status was obtained in 528 patients, mean age 54.5±9.8 years, of which 220 (41.6%) were men. Primary endpoints were recorded in 50 patients. These patients showed more pronounced seasonal variability in blood pressure. However, the variability of the clinical SBP was «normal» on average, and the variability of the nighttime BP was «inverted» (the summer level exceeded the winter level).
CONCLUSION
Significant seasonal fluctuations in blood pressure create problems for the diagnosis of hypertension, the choice of patient management tactics and monitoring the effectiveness of treatment. For the first time, the direct predictive value of seasonal variability in ambulatory blood pressure was shown with daily monitoring. The «inverted» ratio of winter and summer blood pressure is unfavorable.
