Weather-related changes in 24-hour blood pressure profile: effects of age and implications for hypertension management.
A downward titration of antihypertensive drug regimens in summertime is often performed on the basis of seasonal variations of clinic blood pressure (BP). However, little is known about the actual interaction between outdoor air temperature and the effects of antihypertensive treatment on ambulatory BP. The combined effects of aging, treatment, and daily mean temperature on clinic and ambulatory BP were investigated in 6404 subjects referred to our units between October 1999 and December 2003. Office and mean 24-hour systolic BP, as well as morning pressure surge, were significantly lower in hot (>90th percentiles of air temperature; 136+/-19, 130+/-14, and 33.3+/-16.1 mm Hg; P<0.05 for all), and higher in cold (<10th percentiles) days (141+/-12, 133+/-11, and 37.3+/-9.5 mm Hg; at least P<0.05 for all) when compared with intermediate days (138+/-18, 132+/-14, and 35.3+/-15.4 mm Hg). At regression analysis, 24-hour and daytime systolic pressure were inversely related to temperature (P<0.01 for all). Conversely, nighttime systolic pressure was positively related to temperature (P<0.02), with hot days being associated with higher nighttime pressure. Air temperature was identified as an independent predictor of nighttime systolic pressure increase in the group of elderly treated hypertensive subjects only. No significant relationship was found between air temperature and heart rate. Our results show for the first time that hot weather is associated with an increase in systolic pressure at night in treated elderly hypertensive subjects. This may be because of a nocturnal BP escape from the effects of a lighter summertime drug regimen and may have important implications for seasonal modulation of antihypertensive treatment.
Modesti
Pietro Amedeo
PA
Clinica Medica Generale e Cardiologia, University of Florence, Florence, Italy. pamodesti@unifi.it
Morabito
Marco
M
Bertolozzi
Iacopo
I
Massetti
Luciano
L
Panci
Gabriele
G
Lumachi
Camilla
C
Giglio
Alessia
A
Bilo
Grzegorz
G
Caldara
Gianluca
G
Lonati
Laura
L
Orlandini
Simone
S
Maracchi
Giampiero
G
Mancia
Giuseppe
G
Gensini
Gian Franco
GF
Parati
Gianfranco
G
D000368:Aged; D000375:Aging; D000959:Antihypertensive Agents / Q000627:therapeutic use*; D001794:Blood Pressure; D018660:Blood Pressure Monitoring, Ambulatory; D002940:Circadian Rhythm; D002980:Climate; D003430:Cross-Sectional Studies; D006339:Heart Rate; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000453:epidemiology / Q000503:physiopathology*; D008875:Middle Aged; D015995:Prevalence; D013696:Temperature; D014887:Weather
D000959:Antihypertensive Agents