Diagnosing hypertension by intradialytic blood pressure recordings.
OBJECTIVE
The diagnosis of hypertension among hemodialysis patients by predialysis or postdialysis blood pressure (BP) recordings is imprecise and biased and has poor test-retest reliability. The use of intradialytic BP measurements to diagnose hypertension is unknown.


METHODS
A diagnostic-test study was done with interdialytic ambulatory BP as reference standard. Index BP recordings tested were: predialysis (method 1), postdialysis (method 2), intradialytic (method 3), intradialytic including predialyis and postdialysis (method 4), and the average of predialysis and postdialysis (method 5). Each index BP was recorded over six consecutive dialysis treatments.


RESULTS
There were differences among index BP measurements in reproducibility, bias, precision, and accuracy. Method 4 was the most reproducible (intraclass correlation coefficient = 0.70 for systolic and diastolic BP). All 5 measurement methods overestimated 44-h ambulatory systolic BP. Methods 2, 3, or 4 overestimated ambulatory systolic BP by only a small amount. Method 4 was the most precise and accurate. For diagnosis of hypertension, BP cut-point by method 4 of 135/75 mmHg, had a sensitivity of 90.4% and specificity of 75.9% for systolic BP (area under ROC curve 0.90). Median cut-off systolic BP of 140 mmHg from a single dialysis provides approximately 80% sensitivity and 80% specificity in diagnosing systolic hypertension; a median cut-off diastolic BP of 80 mmHg provides approximately 75% sensitivity and 75% specificity in diagnosing diastolic hypertension.


CONCLUSIONS
Consideration of intradialytic BP measurements together with predialysis and postdialysis BP measurements improves the reproducibility, bias, precision, and accuracy of BP measurement compared with predialysis or postdialysis measurements.
Agarwal
Rajiv
R
Division of Nephrology, Department of Medicine, Indiana University School of Medicine and Richard L. Roudebush VA Medical Center, Indianapolis, Indiana, USA. ragarwal@iupui.edu
Metiku
Tesfamariam
T
Tegegne
Getachew G
GG
Light
Robert P
RP
Bunaye
Zerihun
Z
Bekele
Dagim M
DM
Kelley
Ken
K
D000328:Adult; D000368:Aged; D001794:Blood Pressure; D018660:Blood Pressure Monitoring, Ambulatory / Q000379:methods* / Q000592:standards; D003971:Diastole; D005260:Female; D006801:Humans; D006973:Hypertension / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D007674:Kidney Diseases / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012372:ROC Curve; D012015:Reference Standards; D006435:Renal Dialysis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013599:Systole