Abstract and Introduction
Abstract
Background We investigated the effect of having clinic and/or ambulatory blood pressures (BPs) not at goal on cardiorenal risk in patients with non-dialysis-dependent chronic kidney disease (CKD).
Study Design Multicenter prospective study.
Setting & Participants 489 consecutive hypertensive patients with CKD (stages 1–5) with concomitant assessment of ambulatory and clinic BPs followed up in tertiary nephrology clinics.
Predictors Achievement of goal for ambulatory (day- and night-time BPs < 135/85 and <120/70 mm Hg, respectively) and clinic (<140/90 mm Hg) BPs was used to create 4 BP groups: clinic and ambulatory BPs at goal (group 1), clinic BP above goal and ambulatory BP at goal (group 2), clinic BP at goal and ambulatory BP above goal (group 3), and clinic and ambulatory BPs above goal (group 4).
Outcomes Composite cardiovascular event outcome (fatal and nonfatal myocardial infarction, congestive heart failure, stroke, revascularization, peripheral vascular disease, and nontraumatic amputation) and a composite renal outcome (maintenance dialysis therapy or death).
Measurements Clinic and 24-hour ambulatory BPs.
Results Mean age was 64.4 ± 14.2 (SD) years; 41% were women, and diabetes and previous cardiovascular disease were present in 36% and 30%, respectively. Groups 1–4 contained 16.8%, 22.1%, 14.5%, and 46.6%, respectively, of the overall number of participants. Median follow-up was 5.2 years. Compared to group 1, the adjusted risk of the composite cardiovascular outcome was higher in groups 3 (HR, 3.17; 95% CI, 1.50–6.69) and 4 (HR, 2.83; 95% CI, 1.50–5.34), but not in group 2 (HR, 1.55; 95% CI, 0.75–3.19). Similarly, the risk of the composite renal outcome was higher in groups 3 (HR, 3.59; 95% CI, 2.05–6.27) and 4 (HR, 2.96; 95% CI, 1.83–4.78), but not group 2 (HR, 1.24; 95% CI, 0.67–2.27). Sensitivity analyses confirmed thatthese results were independent from the thresholds used for defining groups.
Limitations Only white patients were enrolled. Observational design does not allow for causality to be established.
Conclusions In patients with treated CKD, clinic BP above goal and ambulatory BP at goal identify a lowrisk condition, whereas clinic BP at goal and ambulatory BP above goal are associated with higher cardiorenal risk, similar to that observed in patients with both clinic and ambulatory BPs above goal.
Introduction
Hypertension is the most common complication of chronic kidney disease (CKD), occurring in as many as 90% of patients.[1] Despite guidelines for patients with CKD having repeatedly highlighted the importance of lowering blood pressure (BP) to < 140/90 mm Hg,[2–4] the control rate of hypertension remains unsatisfactory even in tertiary care.[5–7]
Resistance to antihypertensive therapy, very low BP target, and clinical inertia are among the factors that have been proposed to explain poor BP control in patients with CKD.[8,9] However, suboptimal BP assessment may be a determinant of poor hypertension control. Office determination of BP may not be sufficient. Monitoring of 24-hour ambulatory BP allows for better assessment of hypertension control by identifying patients with altered BP profiles, that is, those with clinic BP not at goal and ambulatory BP at goal[10] and vice versa.[11] This assessment is particularly important in CKD because the prevalence of clinic BP not at goal and ambulatory BP at goal and clinic BP at goal and ambulatory BP not at goal appears to differ from that reported in patients with essential hypertension. Specifically, the former is more frequent in patients with CKD (28%) than those with essential hypertension (13%), whereas the latter seems to be less common in patients with CKD (5%) than those with essential hypertension (11%).[10–12] More important, identification of inconsistent achievement of clinic and ambulatory BP goals is helpful at refining prognosis. Three recent meta-analyses in the setting of essential hypertension have shown that clinic BP not at goal and ambulatory BP at goal does not associate with increased cardiovascular (CV) risk, whereas clinic BP at goal and ambulatory BP not at goal predicts a higher risk of CV events.[13–15]
Among patients with CKD, the more accurate estimate of hypertensive status offered by ambulatory BP with respect to clinic BP translates into better risk stratification regarding kidney disease and CV outcome.[16–19] However, at variance with essential hypertension, there is no available information about the independent prognostic role of combining information for clinic and ambulatory BP goals in patients with CKD. Agarwal and Andersen[17,18] have reported in a cohort of patients with CKD a reduced risk of end-stage renal disease and CV events in patients with clinic BP not at goal and ambulatory BP at goal compared with those with both clinic and ambulatory BPs not at goal[17,18] and greater CV risk in patients with clinic BP at goal and ambulatory BP not at goal compared to the presence of both targets at goal.[18] However, in these studies, no independent predictive value emerged after adjustment for cardiorenal risk factors. Furthermore, the studies had major limitations, being restricted to a single center with a limited sample size that included almost exclusively males. In particular, the influence of sex needs to be addressed because the occurrence of clinic BP not at goal and ambulatory BP at goal has been encountered more frequently in females with essential hypertension,[20] and females are at lower risk of progression of CKD and mortality compared with males.[21–23]
This multicenter prospective cohort study of 489 hypertensive patients with CKD was designed to evaluate the impact of having clinic and/or ambulatory BPs at goal on overall prognosis, including fatal and nonfatal CV events, dialysis therapy initiation, and all-cause mortality.
Am J Kidney Dis. 2014;64(5):744-752. © 2014 The National Kidney Foundation
The National Kidney Foundation
Published by Elsevier
