Seasonal variations in home and ambulatory blood pressure in the PAMELA population

Objective Clinic blood pressure values are known to change according to sea sonal influences, We therefore examined home and 24 h ambulatory blood pres sure values to determine whether these measurements are also affected by th e seasons. Design and methods In 2051 subjects of the Pressione Arteriose Monitorate E Lore Associazioni (PAMELA) study, we measured clinic (sphygmomanometric me asurements), home (semi-automatic device) and ambulatory (Spacelabs 90207) systolic blood pressure, diastolic blood pressure and heart rate. Because t he overall sample was evenly distributed over each month (except August), w e were able to make a cross-sectional determination of whether the values d iffered between seasons. The corresponding heart rates were also evaluated. Results As expected, summer wits associated with the lowest clinic blood pr essure and winter with the highest, and this was the case also for home and 24 h average blood pressure, although seasonal differences in the latter w ere less pronounced. Seasonal clinic, home and ambulatory blood pressure pa tterns were similar for normotensive subjects (n =1152), untreated hyperten sives (n = 540) and treated hypertensives (n = 359), Heart rate values did not differ by season. Conclusions Seasonal influences on blood pressure are not limited to conven tional measurements but characterize daily values as well. These effects ar e visible in both normal and elevated blood pressure values, regardless of the effect of antihypertensive drugs. This has implications both for the cl inician and for studies aimed at evaluating the effects of antihypertensive treatment J Hypertens 1998, 16:1585-1592 (C) Lippincott Williams & Wilkins .