Association of blood pressure with decline in renal function and time until the start of renal replacement therapy in pre-dialysis patients: a cohort study

<p>Abstract</p> <p>Background</p> <p>To investigate whether high blood pressure accelerates renal function decline in patients with advanced chronic kidney disease (CKD), we studied the association of systolic (SBP) and diastolic blood pressure (DBP) with decline in renal function and time until the start of renal replacement therapy (RRT) in patients with CKD stages IV-V on pre-dialysis care.</p> <p>Methods</p> <p>In the PREPARE-1 cohort 547 incident pre-dialysis patients, referred as part of the usual care to outpatient clinics of eight Dutch hospitals, were included between 1999 and 2001 and followed until the start of RRT, mortality, or end of follow-up (January 1^st2008). Main outcomes were rate of decline in renal function, estimated as the slope of available eGFR measurements, and time until the start of RRT.</p> <p>Results</p> <p>A total of 508 patients, 57% men and median (IQR) age of 63 (50-73) years, were available for analyses. Mean (SD) decline in renal function was 0.35 (0.75) ml/min/1.73 m²/month. Every 10 mmHg increase in SBP or DBP resulted in an accelerated decline in renal function (adjusted additional decline 0.04 (0.02;0.07) and 0.05 (0.00;0.11) ml/min/1.73 m²/month respectively) and an earlier start of RRT (adjusted HR 1.09 (1.04;1.14) and 1.16 (1.05;1.28) respectively). Furthermore, patients with SBP and DBP above the BP target goal of < 130/80 mmHg experienced a faster decline in renal function (adjusted additional decline 0.31 (0.08;0.53) ml/min/1.73 m²/month) and an earlier start of RRT (adjusted HR 2.08 (1.25;3.44)), compared to patients who achieved the target goal (11%). Comparing the decline in renal function and risk of starting RRT between patients with only SBP above the target (≥ 130 mmHg) and patients with both SBP and DBP below the target (< 130/80 mmHg), showed that the results were almost similar as compared to patients with both SBP and DBP above the target (adjusted additional decline 0.31 (0.04;0.58) ml/min/1.73 m²/month and adjusted HR 2.24 (1.26;3.97)). Therefore, it seems that especially having SBP above the target is harmful.</p> <p>Conclusions</p> <p>In pre-dialysis patients with CKD stages IV-V, having blood pressure (especially SBP) above the target goal for CKD patients (< 130/80 mmHg) was associated with a faster decline in renal function and a later start of RRT.</p

Association between time of referral and survival in the first year of dialysis in diabetics and the elderly

Objective. The objective of the study was to estimate the association between time of referral and survival during dialysis in diabetics and patients aged >= 70 years. Design, setting and subjects. This study was a prospective follow-up study in 1438 incident dialysis patients (1996-2004, 62% male, 60 +/- 15 years) in The Netherlands. Main outcome measures. Referral (time between first pre-dialysis visit to a nephrologist and dialysis initiation) was classified as: late ( = 12 months). All-cause mortality risk within the first year of dialysis was calculated [HR (95% confidence interval, CI), adjusted for age, sex and primary kidney disease (PKD)]. Additive interaction between time of referral and diabetes mellitus (adjusted for age and sex) or age (adjusted for sex and PKD) was assessed by synergy index [S (95% CI)]. Results. Thirty-two percent were late referred, 12% early and 56% very early; 21% had diabetes; and 30% were >= 70 years. Early and late referrals were associated with increased mortality compared with very early referral [HR(adj)early: 1.5 (1.0, 2.4), late: 1.8 (1.3, 2.5)]. A similar trend was observed in diabetics and non-diabetics. However, no interaction between time of referral and diabetes was present [S-late 0.8 (0.4, 1.9), S-early 1.2 (0.4, 3.6)]. Likewise, in patients aged = 70 years, time of referral was associated with increased mortality, without interaction [S-late 0.9 (0.4, 1.8), S-early 0.8 (0.3, 2.0)]. Conclusion. Late referral is associated with increased mortality in the first year of dialysis. Diabetes or high age does not have an additional worsening effect, implying that timely referral is important in future dialysis patients irrespective of diabetes or high ag

Disordered mineral metabolism is not a risk factor for loss of residual renal function in dialysis patients

BACKGROUND: Recent studies showed that mineral metabolism disorders are associated with renal function loss in pre-dialysis patients, but their effects in dialysis patients are less well established. We examined associations between parameters of mineral metabolism and loss of residual renal function (RRF) in dialysis patients. METHODS: We included 1468 incident haemodialysis (HD) and peritoneal dialysis (PD) patients who were not anuric at dialysis initiation from NECOSAD, a prospective multicentre cohort study. We studied the effects of plasma calcium, phosphorus, calcium-phosphorus product and intact PTH concentrations on loss of RRF. Cox regression models were applied to calculate relative risks of total loss of RRF, defined as anuria during the first 3 years of dialysis. The rate of decline of RRF over time was calculated using general linear mixed models. RESULTS: The mean (SD) age was 59 (15), 62% were men and 59% were treated with HD. We found that both HD and PD patients with the highest phosphorus (P < 0.0001) and calcium-phosphorus product (P < 0.0001) levels had the lowest baseline residual glomerular filtration rate (rGFR) values. During follow-up, 136 HD (15%) and 67 PD patients (12%) became anuric. After adjustment for baseline rGFR, there were no significant associations between parameters of mineral metabolism and the risk of becoming anuric. There were also no differences in the rate of decline in RRF between categories of plasma concentrations. CONCLUSION: Disordered mineral metabolism was neither associated with the risk of becoming anuric, nor with the rate of decline in RRF in dialysis patients. Differences in decline were mainly attributable to the baseline rGFR valu

High plasma phosphate as a risk factor for decline in renal function and mortality in pre-dialysis patients

Background. Hyperphosphataemia is associated with increased mortality in patients with chronic kidney disease (CKD) stage IV or on dialysis. Furthermore, in animal studies, elevated plasma phosphate has been shown to be associated with an accelerated decline in renal function. The aim of this study was to determine the association of plasma phosphate with renal function loss and mortality in CKD stage IV - V pre-dialysis patients with GFR <20 ml/min/1.73 m(2). Methods. Incident pre-dialysis patients were included between 1999 and 2001 in the multi-centre PREPARE study, and followed until 2003 or death. Rate of decline in renal function for each patient was calculated by linear regression using the Modification of Diet in Renal Disease (MDRD) formula to estimate GFR (eGFR). Results. A total of 448 patients were included [mean (SD) age 60 (15) years, eGFR 13 (5.4) ml/min/1.73 m(2), decline in renal function 0.38 (0.95) ml/min/ month]. Phosphate concentration at baseline was 4.71 (1.16) mg/dl, calcium 9.25 (0.77) mg/dl and calcium - phosphate product 43.5 (10.9) mg(2)/dl(2). For each mg/dl higher phosphate concentration, the mean (95% CI) decline in renal function increased with 0.154 (0.071 - 0.237) ml/min/ month. After adjustment, this association remained [beta 0.178 ( 0.082 - 0.275)]. Seven percent of the patients died. Crude mortality risk was 1.25 (0.85 - 1.84) per mg/dl increase in phosphate, which increased to 1.62 (1.02 - 2.59) after adjustment. Conclusions. High plasma phosphate is an independent risk factor for a more rapid decline in renal function and a higher mortality during the pre-dialysis phase. Plasma phosphate within the normal range is likely of vital importance in pre-dialysis patients