NDT Advance Access originally published online on January 24, 2006
Nephrology Dialysis Transplantation 2006 21(4):1126-1127; doi:10.1093/ndt/gfk066
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Association between BP and mortality in patients on chronic peritoneal dialysis
Email: alokk{at}sgpgi.ac.inSir,
We read with interest the article by Goldfarb-Rumyantzev et al. [1] on the association between blood pressure (BP) and mortality in patients on chronic peritoneal dialysis. It brought out certain surprising observations, such as the protective effect of high BP on hospitalization as well as higher mortality with higher creatinine clearance. Because adverse effects of high BP take a long time to manifest, the authors may not have been able to demonstrate adverse effects. Foley et al. also showed that each increment of 10 mmHg mean BP was associated with a higher risk (44%) of developing heart failure [2]. The higher mortality with higher peritoneal creatinine clearance could reflect the confounding effect of the high transport status. Rapid transporters face higher mortality on continuous ambulatory peritoneal dialysis (CAPD) [3]. The article concludes that systolic BP <111 mmHg is associated with higher mortality in patients on PD. However, the association was significant in patients with a history of heart failure, diabetic patients and patients on antihypertensive medications. It appears that higher mortality is a reflection of poor cardiac status, as patients with a history of heart failure probably have poor cardiac function. Diabetics are also prone to a higher number of cardiac complications due to cardiomyopathy and coronary artery disease. There is a suggestion in dialysis [4] as well as in the normal population, that the U-shaped curve is due to cardiac problems per se, not due, to BP. Low BP values are predictive of higher mortality in the short term only. Long-term observations show that patients on dialysis with normal BP have a reduced mortality rate, compared to those with high BP [5]. Higher mortality with better BP control in patients on antihypertensive drugs may reflect a drug selection bias. Carvedilol has been found to improve survival in dialysis patients with cardiomyopathy. Patients on angiotensin-converting enzyme inhibitors have better regression of left ventricular hypertrophy, independently of BP control. Angiotensin receptor blockers preserve residual renal function better, which is a marker of better survival in this study. It would be interesting to look at records of cardiac function in all patients. In sum, it is difficult to conclude that systolic BP <111 mmHg is associated with higher mortality in patients on PD.
Conflict of interest statement. None declared.
Department of Nephrology Sanjay Gandhi Post Graduate Institute of Medical Sciences Lucknow 226014 India
References
- Goldfarb-Rumyantzev AS, Bradley R, Baird C, Leypoldt JK, Cheung AK. The association between BP and mortality in patients on chronic peritoneal dialysis. Nephrol Dial Transplant 2005; 20: 1693–1701
[Abstract/Free Full Text] - Foley RN, Parfrey PS, Harnett JD et al. Impact of hypertension on cardiomyopathy, morbidity and mortality in end stage renal disease. Kidney Int 1996; 49: 1379–1385[Web of Science][Medline]
- Churchill DN, Thorpe KD, Nolph KD et al. Increased peritoneal transport is associated with CAPD technique and survival. J Am Soc Nephrol 1997; 8: 189A
- Zoccali C. Cardiovascular risk in uremic patients—is it fully explained by classical risk factors? Nephrol Dial Transplant 2000; 15: 454–457
[Free Full Text] - Mazzuchi N, Carbonell E, Fernandez-Cean J. Importance of BP control in hemodialysis patient survival. Kidney Int 2000; 58: 2147–2154[CrossRef][Web of Science][Medline]
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