S. Majahalme et al., BLOOD-PRESSURE LEVEL AND VARIABILITY IN THE PREDICTION OF BLOOD-PRESSURE AFTER 5-YEAR FOLLOW-UP, Hypertension, 28(5), 1996, pp. 725-731
We compared mean intra-arterial ambulatory blood pressure (IAMB), bloo
d pressure (BP) diurnal profiles and variability, and postural measure
ments with casual sphygmomanometric measurements for the prediction of
future BP. We studied 97 healthy, unmedicated men classified as normo
tensive (NT, n = 34). borderline hypertensive (BHT, n = 29), or mildly
hypertensive (HT, n = 34) by repeated casual measurements during the
2 months before IAMB. Five years later, we reassessed 79 subjects (81%
) using casual BP measurements and noninvasive ambulatory 24-hour BP m
onitoring (NAME). IAMB level generally correlated well with follow-up
BP and slightly better with NAME level than with casual measurements (
24-hour IAMB versus follow-up NAME systolic BP [SEP], r = .64, P < .00
1; versus diastolic BP [DBP], r = .52, P < .001). NT and BHT subgroup
correlations were of similar strength, but the relationship in the HT
subgroup was not significant. Similarly, when we examined daytime and
nighttime BP levels, nighttime BP correlated better with follow-up BP
in NT and BHT but not in HT. The only measures that were significantly
related to follow-up BP in HT were two BP variability measures, SD an
d the range of variability (RV(80): 90th minus 10th percentile) (initi
al 24-hour IAMB SD and follow-up BP, r = .42 to r = .52, P < .05 to P
< .01; RV(80) versus follow-up BP, r = .43 to r = .52, P < .05 to P <
.01). Correlations of follow-up BP with postural BP were generally wea
ker than with casual BP or IAMB level. Linear stepwise regressions for
SEP and DBP separately (including all IAMB variables) demonstrated th
at the best single predictor for follow-up BP was 24-hour IAMB SEP lev
el, which explained 41% of follow-up NAME SEP level variance (F = 52.6
, P < .001). However, in a second analysis including casual values, ca
sual SEP alone explained 44% of follow-up NAME SEP variance (F = 62.5,
P < .001), whereas IAMB SEP added only 4% (F = 5.5, P < .05). Predict
ions of follow-up DBP were always poorer. After 5 years, 70% of NT and
86% of HT were still in their initial classification group, but 67% o
f BHT had become hypertensive. In these new HT (n = 16), initial IAMB
level correlated most strongly with follow-up NAME level (24-hour SEP,
r = .70, P < .01; 24-hour DBP, r = .55, P < .05). The only other sign
ificant demographic variable predicting future BP was change in weight
over 5 years, which added 10% to the explanation of future casual Ssp
variance (F = 12.5, P = .0007) and 15% to casual DBP variance (F = 18
.0, P = .0001); for NAME, the percentages were lower. In logistic regr
ession, those NT and BHT who became hypertensive (n = 22) had a 75% pr
obability of becoming hypertensive if they gained 11.7 kg or more duri
ng 5 years (chi(2) = 4.5, P = .03). To conclude, BP tended to increase
in all groups, especially in BHT, during follow-up. Nominal differenc
es were observed between casual measurements and BP level measures in
the prediction of future BP, and their explanatory value for future BP
was generally less than 50%. However, for BHT who became hypertensive
, BP level and variability measurements somewhat improved the predicti
on of follow-up BP. Weight gain was an important additional predictor
for future hypertension in both NT and BHT.