Time-Updated BP Shows Stronger Association with CKD Progression

Compared with one-time measurement, time-updated BP values are a stronger predictor of chronic kidney disease (CKD) progression, reports a study in the Annals of Internal Medicine.

The prospective Chronic Renal Insufficiency Cohort Study included 3708 patients with mild to moderate CKD who were enrolled at seven centers in the United States between 2003 and 2008. At annual clinic visits, the visit-specific systolic BP (SBP) was determined as the mean of three seated SBP measurements. Time-updated SBP was calculated as the mean of that value and all previous visit-specific values.

Visit-specific and time-updated SBPs were compared for association with progression to ESRD and with a composite endpoint of ESRD or halving of the estimated GFR. Analyses were adjusted for time-updated covariates.

Over a median 5.7 years of follow-up, 19.2 percent of patients had an SBP of 130 mm Hg or greater at all visits. When baseline data only were used, the hazard ratio for ESRD associated with SBP of 130 to 139 mm Hg was 1.46 (compared with SBP less than 120 mm Hg). For a time-updated SBP of 130 to 139 mm Hg, the HR was 2.37.

Time-updated BP measurements are more strongly linked to risk of progressive CKD than are baseline SBP values. “[P]rolonged exposure to SBP greater than 130 mm Hg may portend increased risk for progressive loss of kidney function among persons with CKD regardless of diabetes or proteinuria status,” the researchers write. They call for further studies to assess the relevance of time-updated BP for clinical practice guidelines [Anderson AH, et al. Time-updated systolic blood pressure and the progression of chronic kidney disease: a cohort study. Ann Intern Med 2015; 162:258–265].