PP Declines Predict Worse HD Patient Survival
PP Declines Predict Worse HD Patient Survival
PRAGUE—Decreases in pulse pressure (PP), and to a lesser extent increases, predict worse survival in the first year for patients new to hemodialysis (HD), new findings suggest. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) changes also are associated with poorer outcomes.
These results are consistent across the entire range of blood pressure (BP) and pulse pressure measurements within the first 30 days of starting dialysis.
Reporting his results here at the 48th Congress of the European Renal Association-European Dialysis and Transplant Association, Len Usvyat, MS, Senior Clinical Database Analyst at the Renal Research Institute in New York, noted that clinicians do not often consider changes in SBP and DBP in practice beyond the previous month, and they rarely consider changes in PP. A decrease in blood pressure (BP) is usually seen as a good sign.
Usvyat and colleagues reviewed the records of new HD patients with at least 13 treatments in the first year at the Renal Research Institute from January 2000 to February 2010. As a baseline, they used each patient's average SBP, DBP, and PP over the first 30 days of treatment and then determined the slope of the changes in each patient's values during the first year on dialysis. The investigators considered PP to have increased if it rose on average by more than 1 mm Hg/month, to decrease if it declined by that amount, or to be stable.
Data came from 10,245 patients with an average age of 62.1 years, of whom 57% were men, 38% Black, 54% white, and 54% had diabetes. The survival analysis was adjusted for demographic factors, a variety of co-morbidities, body mass index, serum albumin, interdialytic weight gain, and the use of cardiac drugs.
Stable pressures are best
Using patients with stable SBP starting in the 151-180 mm Hg range as the reference, the researchers calculated hazard ratios for the risk of dying during the first year of HD according to ranges of SBP in the first 30 days on dialysis (less than 120, 120-150, 151-180, and greater than 180 mm Hg).
“Stable systolic blood pressures are really the best group to be in regardless of where the patient starts in the very beginning of their treatment,” Usvyat reported. His team observed the highest risk of death (8.4 times increased risk compared with the reference patients) among patients with starting SBP less than 120 mm Hg and then declining over the year. Increasing SBP for this group was associated with a significant 3.6 times increased death risk.
For the highest starting SBP's (greater than 180 mm Hg), a decrease and an increase were each associated with a threefold increased death risk. For patients with stable SBP's, regardless of the starting values, the investigators observed no increased risk of death in relation to the comparator.
The same relationship held for patients in all strata of initial DBP (less than 65, 65-75, 76-85, and greater than 85 mm Hg). Patients with stable DPB's had the lowest risk of death in the first year. Patients who started out with the lowest DBP's had a significant sevenfold increased risk, the highest observed.
Increasing pressure in this group resulted in a greater than fourfold risk of death. In patients with the highest starting DBP, a decline in pressure was associated with a 2.7-fold elevated risk. An increase among patients in this stratum resulted in a 4.6-fold increased risk (all DBP risks compared with stable patients in the 76-85 mm Hg band).
Changes in SBP were largely responsible for the changes in PP. In about 89% of the patients with a PP decrease, the decline resulted from a decrease in the SBP, and the remaining patients had an increase in DBP. Most of the increases in PP were attributable to rising SBP, with few patients having a drop in DBP, “again suggesting that it's the systolic [pressure] that's causing most of the changes in the pulse pressure,” Usvyat said.
The investigators, therefore, adjusted the PP hazard ratios for SBP and the slope of change in SBP to account for the large influence of these factors on PP. They observed that at every range of initial PP, stable patients had the best survival. A decrease in SBP was associated with a twofold to nearly threefold increased death risk, whereas an increase in PP was associated with a significant 43%-86% increase in death risk.
Based on his findings, Usvyat proposed that “not only observation of the systolic blood pressure but also pulse pressure and its temporal changes may be recommended in the clinical care of incident hemodialysis patients.”