Jg. Vandijk et al., EFFECTS OF SUPINE BLOOD-PRESSURE ON INTERPRETATION OF STANDING UP TEST IN 500 PATIENTS WITH DIABETES-MELLITUS, Journal of the autonomic nervous system, 47(1-2), 1994, pp. 23-31
The relationship between fall in blood pressure (BP) on standing and s
upine BP before standing up was studied in 75 healthy controls and in
500 patients with diabetes mellitus (DM) using conventional BP measure
ments. The influences of physiological (sex, age, height) and DM-relat
ed factors (type, duration, HbA(1c)-level, use of insulin, oral antidi
abetic and anti-hypertensive medication) on BP-fall were assessed. The
effects of using a fixed abnormality threshold and a new supine BP-re
lated abnormality definition on interpretation of the test were determ
ined. Highly significant relationships of BP-fall with supine BP were
found in control and DM subjects. Slopes did not differ between these
groups. Slopes for systolic BP-fall were steeper in type 1 than in typ
e 2 DM patients. A forward stepwise regression procedure revealed that
supine BP (explaining 24% of variance) and HbA(1c) (explaining 1%) ha
d significant influences on systolic BP-fall. Diastolic supine BP expl
ained 14% of diastolic BP-fall, age 3%, and sex 2%. Only supine BP was
thus of practical relevance in explaining BP-fall. Taking supine BP i
nto consideration affected test results: of 74 subjects with an abnorm
al conventional systolic BP-fall, 10 (13.5%) had been misclassified ac
cording to the new method, and 4 additional patients had been misclass
ified as normal. Classification changes were much larger for diastolic
BP-fall (63% of conventionally abnormal results were reclassified as
normal), but the range of diastolic BP is smaller than for systolic BP
, meaning that the measurement error interferes with its clinical util
ity. BP-fall was higher in type 2 than in type 1 diabetics, and higher
in those using anti-hypertensives than in those who did not. These ef
fects were due to differing supine BPs, showing that taking supine BP
into account can prevent incorrect conclusions regarding abnormality o
f the standing up test in DM. The validity of this test can be improve
d by accounting for supine BP.