Masked Uncontrolled Hypertension in CKD

Abstract

Masked uncontrolled hypertension (MUCH) is diagnosed in patients treated for hypertension who are normotensive in the clinic but hypertensive outside. In this study of 333 veterans with CKD, we prospectively evaluated the prevalence of MUCH as determined by ambulatory BP monitoring using three definitions of hypertension (daytime hypertension ≥135/85 mmHg; either nighttime hypertension ≥120/70 mmHg or daytime hypertension; and 24-hour hypertension ≥130/80 mmHg) or by home BP monitoring (hypertension ≥135/85 mmHg). The prevalence of MUCH was 26.7% by daytime ambulatory BP, 32.8% by 24-hour ambulatory BP, 56.1% by daytime or night-time ambulatory BP, and 50.8% by home BP. To assess the reproducibility of the diagnosis, we repeated these measurements after 4 weeks. Agreement in MUCH diagnosis by ambulatory BP was 75-78% (κ coefficient for agreement, 0.44-0.51), depending on the definition used. In contrast, home BP showed an agreement of only 63% and a κ coefficient of 0.25. Prevalence of MUCH increased with increasing clinic systolic BP: 2% in the 90-110 mmHg group, 17% in the 110-119 mmHg group, 34% in the 120-129 mmHg group, and 66% in the 130-139 mmHg group. Clinic BP was a good determinant of MUCH (receiver operating characteristic area under the curve 0.82; 95% confidence interval 0.76-0.87). In diagnosing MUCH, home BP was not different from clinic BP. In conclusion, among people with CKD, MUCH is common and reproducible, and should be suspected when clinic BP is in the prehypertensive range. Confirmation of MUCH diagnosis should rely on ambulatory BP monitoring.

Keywords: blood pressure; chronic kidney disease; hypertension.

Figure 1.

Overview of study design. After a brief history and physical examination, participants had BP measured in a seated position. The technique of HBPM was explained and a self-inflating oscillometric device was dispensed. For one week, each participant recorded home BP twice daily. ABPM was performed over 24 hours. After one month hiatus, the study was repeated as in the initial month. CBP, clinic BP; HBPM, home BP monitoring.

Figure 2.

Bivariate distribution of hypertension categories by visit. (A) Number of participants who had hypertensive clinic BP (left bar) or were normotensive (right bar). If clinic BP was in the hypertensive range, but ambulatory BP was normal isolated clinic hypertension (ICH) was diagnosed, or if ambulatory BP was high, they were said to have uncontrolled hypertension (UCH). If clinic BP was normal and ambulatory BP was normal they had controlled hypertension (CH), or if ambulatory BP was elevated they were diagnosed with MUCH. (B) The reason why participants were diagnosed with UCH or MUCH. UCH during daytime only (UCH-D), daytime or nightime (UCH-DN), or nighttime only (UCH-N) pie-chart is shown. Similarly MUCH breakdown as a pie chart by ambulatory BP monitoring elevation during daytime (MUCH-D), daytime or nighttime (MUCH-DN), and nighttime alone (MUCH-N) are shown. (C) and (D) Data from repeat measurements at week 4.

Figure 3.

Receiver operating characteristic (ROC) curves for the diagnosis of MUCH). ROC curves for the diagnostic test performance of systolic clinic and home BP in predicting MUCH diagnosed by daytime ambulatory hypertension (135/85 mmHg) at baseline visit (A) and after 1 month (B). The area under the curve (AUC) for clinic and home BP monitoring were similar (P=0.38 and 0.14, respectively) at each of the two visits.