The Modification of Diet in Renal Disease (MDRD) Study equation underestimates glomerular filtration rate (GFR) in patients with mild kidney disease. Levey and associates therefore developed and va...

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A New Equation to Estimate Glomerular Filtration Rate

The National High Blood Pressure Education Program presents the complete Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. Like its predecessors, the purpose is to provide an evidence-based approach to the prevention and management of hypertension. The key messages of this report are these: in those older than age 50, systolic blood pressure (BP) of greater than 140 mm Hg is a more important cardiovascular disease (CVD) risk factor than diastolic BP; beginning at 115/75 mm Hg, CVD risk doubles for each increment of 20/10 mm Hg; those who are normotensive at 55 years of age will have a 90% lifetime risk of developing hypertension; prehypertensive individuals (systolic BP 120-139 mm Hg or diastolic BP 80-89 mm Hg) require health-promoting lifestyle modifications to prevent the progressive rise in blood pressure and CVD; for uncomplicated hypertension, thiazide diuretic should be used in drug treatment for most, either alone or combined with drugs from other classes; this report delineates specific high-risk conditions that are compelling indications for the use of other antihypertensive drug classes (angiotensin-converting enzyme inhibitors, angiotensin-receptor blockers, beta-blockers, calcium channel blockers); two or more antihypertensive medications will be required to achieve goal BP (<140/90 mm Hg, or <130/80 mm Hg) for patients with diabetes and chronic kidney disease; for patients whose BP is more than 20 mm Hg above the systolic BP goal or more than 10 mm Hg above the diastolic BP goal, initiation of therapy using two agents, one of which usually will be a thiazide diuretic, should be considered; regardless of therapy or care, hypertension will be controlled only if patients are motivated to stay on their treatment plan. Positive experiences, trust in the clinician, and empathy improve patient motivation and satisfaction. This report serves as a guide, and the committee continues to recognize that the responsible physician's judgment remains paramount.

Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure

The serum creatinine concentration is widely used as an index of renal function, but this measure is affected by factors other than the glomerular filtration rate (GFR). This study examined an equa...

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A more accurate method to estimate glomerular filtration rate from serum creatinine: A new prediction equation

K/DOQI clinical practice guidelines for chronic kidney disease: Evaluation, classification, and stratification

Background End-stage renal disease substantially increases the risks of death, cardiovascular disease, and use of specialized health care, but the effects of less severe kidney dysfunction on these outcomes are less well defined. Methods We estimated the longitudinal glomerular filtration rate (GFR) among 1,120,295 adults within a large, integrated system of health care delivery in whom serum creatinine had been measured between 1996 and 2000 and who had not undergone dialysis or kidney transplantation. We examined the multivariable association between the estimated GFR and the risks of death, cardiovascular events, and hospitalization. Results The median follow-up was 2.84 years, the mean age was 52 years, and 55 percent of the group were women. After adjustment, the risk of death increased as the GFR decreased below 60 ml per minute per 1.73 m2 of body-surface area: the adjusted hazard ratio for death was 1.2 with an estimated GFR of 45 to 59 ml per minute per 1.73 m2 (95 percent confidence interval, 1....

https://www.nejm.org/doi/pdf/10.1056/NEJMoa041031

Chronic kidney disease and the risks of death, cardiovascular events, and hospitalization

A simplified equation to predict glomerular filtration rate from serum creatinine

Methods: The prediction equation was developed by stepwise regression applied to the training sample. The equation was then tested and compared with other prediction equations in the validation sample. Results: To simplify prediction of GFR, the equation included only demographic and serum variables. Independent factors associated with a lower GFR included a higher serum creatinine concentration, older age, female sex, nonblack ethnicity, higher serum urea nitrogen levels, and lower serum albumin levels (P , 0.001 for all factors). The multiple regression model explained 90.3% of the variance in the logarithm of GFR in the validation sample. Measured creatinine clearance overestimated GFR by 19%, and creatinine clearance predicted by the Cockcroft‐Gault formula overestimated GFR by 16%. After adjustment for this overestimation, the percentage of variance of the logarithm of GFR predicted by measured creatinine clearance or the Cockcroft‐Gault formula was 86.6% and 84.2%, respectively. Conclusion: The equation developed from the MDRD Study provided a more accurate estimate of GFR in our study group than measured creatinine clearance or other commonly used equations.

Annals of Internal Medicine A More Accurate Method To Estimate Glomerular Filtration Rate from Serum Creatinine: A New Prediction Equation

Factors other than the glomerular filtration rate (GFR) can affect creatinine clearance (Ccr) and serum creatinine concentration (Pcr). The effect of dietary protein and antihypertensive therapy on Ccr the reciprocal of the Pcr (1/Pcr). and their determinants (GFR, creatinine clearance from tubular secretion (CTScr), and creatinine excretion (UcrV) values) was assessed in patients participating in the Modification of Diet in Renal Disease (MDRD) Study. This study compared the effects of assignment to a low versus usual-protein diet and to a low versus usual-blood pressure goal on the decline in these measurements over 3 yr in 585 patients with baseline GFR of 25 to 55 mL/min per 1.73 m2 (Study A). This study also assessed correlations and associations of these measurements with each other and with protein intake, blood pressure, class of antihypertensive agents, and renal diagnosis in 840 patients with baseline GFR of 13 to 55 mL/min per 1.73 m2 (Studies A and B). In Study A, the estimated mean decline in GFR at 3 yr did not differ significantly between the low and usual-protein diet groups (-10.9 versus -12.1 mL/min). In contrast, CTScr declined more in the low-protein diet group (-7.8 versus -3.6 mL/min, P < .05). Consequently, the low-protein diet group had a greater decline in Ccr (-17.6 versus -14.4 mL/min, P < .05). The low-protein diet group also had a greater decline in UcrV (-306 versus -92 mg/day, P < .05). The decline in UcrV was proportionately greater than the decline in CTScr hence the decline in 1/Pcr was less in the low-protein diet group (-0.091 versus -0.122 dl/mg, P < .05). Similarly, in Study A, there was no significant difference in the decline in GFR at 3 yr between the low and usual-blood pressure groups (-10.7 versus -12.3 mL/ min). However, there was a lesser decline in CTScr in the low blood pressure group (-4.7 versus -6.7 mL/ min, P < .05). Consequently, the decline in Ccr was less in the low blood pressure group (-14.2 versus -17.8 mL/min, P < .05). There was no significant difference in UcrV between the blood pressure groups (-192 versus -205 mg/day). Hence, the decline in 1/Pcr paralleled the decline in Ccr; it was less in the low blood pressure group (-0.091 versus -0.122 dL/mg, P < .05). In Studies A and B, correlations of rates of decline in Ccr and GFR were 0.64 and 0.79, respectively (P < 0.001). Correlations of rates of decline in 1/Pcr and GFR were 0.79 and 0.85, respectively (P < 0.001). In Studies A and B combined, baseline GFR, CTScr and UcrV correlated significantly with protein intake (r = 0.45, 0.47, and 0.36, respectively; P < 0.001), but not with blood pressure. Baseline CTScr was significantly lower in patients with polycystic kidney disease and tubulointerstitial diseases or urinary tract diseases, compared with glomerular and other diseases (P < 0.05). It was also lower in patients who were taking calcium channel blockers, compared with patients not taking these agents, and in patients not taking diuretics, compared with patients taking diuretics (P < 0.05). These results show that creatinine secretion and excretion are affected by protein intake. Creatinine secretion is also affected by antihypertensive therapy and renal diagnosis. In the MDRD Study, the low-protein diet reduced creatinine secretion and excretion, and the low blood pressure goal slowed the decline in creatinine secretion. These effects caused differences between the diet groups and between the blood pressure groups in Ccr and 1/Pcr that were not the result of differences in GFR. Studies assessing the effects of these interventions on the progression of renal disease should measure GFR in addition to Ccr and Pcr.

Effects of Diet and Antihypertensive Therapy on Creatinine Clearance and Serum Creatinine Concentration in the Modification of Diet in Renal Disease Study

Convective therapies such as hemofiltration, hemodiafiltration and double high flux dialysis have been shown to improve treatment delivered and treatment tolerance when compared to conventional dialysis therapies. The risk associated with these treatments is primarily in the quality of the substitution fluid. Technological advances now permit on-line produced substitution fluid, thereby significantly reducing the cost associated with hemofiltration and hemodiafiltration. The quality of the substitution fluid is only assured when the quality of the RO water used is within the guidelines set by the Association for the Advancement of Medical Instrumentation (AAMI). Therefore, the success of the application of this therapy is dependent on the water treatment protocols in the dialysis units. The success of this modality as a treatment for chronic renal failure is dependent on identifying those patient groups who will benefit most from this more efficient but more expensive treatment.

Juan P. Bosch

Papers

A more accurate method to estimate glomerular filtration rate from serum creatinine: A new prediction equation

A simplified equation to predict glomerular filtration rate from serum creatinine

Annals of Internal Medicine A More Accurate Method To Estimate Glomerular Filtration Rate from Serum Creatinine: A New Prediction Equation

Effects of Diet and Antihypertensive Therapy on Creatinine Clearance and Serum Creatinine Concentration in the Modification of Diet in Renal Disease Study

Hemofiltration and double high flux dialysis: risks and benefits.