Blood pressure recordings within and outside the clinic and cardiovascular events in chronic kidney disease.

BACKGROUND

Blood pressure (BP) measured outside the clinic correlates better with cardiovascular outcomes in patients with essential hypertension. To assess the role of out-of-clinic BP recordings in predicting cardiovascular events in patients with chronic kidney disease (CKD), a prospective cohort study was conducted in 217 veterans with CKD.

METHODS

BP was measured outside the clinic at home and by 24-hour ambulatory recordings, and in the clinic by 'routine' and standardized methods. Patients were followed over a median of 3.4 years to assess the combined end-point of total mortality, myocardial infarction or stroke.

RESULTS

Average (+/-SD) home BP was 147.0 +/- 21.4/78.3 +/- 11.6 mm Hg, 24-hour ambulatory BP 133.5 +/- 16.6/73.1 +/- 11.1 mm Hg and in-clinic BPs were 155.2 +/- 25.6/84.7 +/- 14.2 mm Hg by the standardized method, and 144.5 +/- 24.2/75.4 +/- 14.7 mm Hg by the 'routine' method. A 1 SD increase in systolic BP increased the hazard ratio (HR) of the composite end-point by 1.16 (95% CI 0.89-1.50) for routine BP, 1.57 (95% CI 1.19-2.09) for standardized BP, 1.66 (95% CI 1.27-2.17) for home BP, and 1.42 (95% CI 1.10-1.84) for 24-hour ambulatory BP recording. The HR of the composite end-point was only significant for hypertension defined by 24-hour ambulatory BP monitoring (HR 2.22 (95% CI 1.23-4.01)). Adjusted for the propensity scores, BP measured by the ambulatory technique was not an independent predictor of cardiovascular events. Non-dipping was associated with increased cardiovascular risk, but not when adjusted for other risk factors.

CONCLUSION

Risk factors that differentiate hypertension or non-dipping appear to confer a cardiovascular risk in CKD.