Higher Strength Lanthanum Carbonate Provides Serum Phosphorus Control With a Low Tablet Burden and Is Preferred by Patients and Physicians: A Multicenter Study

Background and objectives: Management of hyperphosphatemia, a predictor of mortality in chronic kidney disease, is challenging. Nonadherence to dietary phosphate binders, in part, contributes to uncontrolled serum phosphorus levels. This phase IIIb trial assessed the efficacy of increased dosages (3000 to 4500 mg/d) of reformulated lanthanum carbonate (500-, 750-, and 1000-mg tablets) in nonresponders to dosages of up to 3000 mg/d.

Design, setting, participants, & measurements: This 8-wk study with a 4-mo open-label extension enrolled 513 patients who were undergoing maintenance hemodialysis. Patients who achieved serum phosphorus control at week 4 with ≤3000 mg/d lanthanum carbonate entered cohort A; nonresponders were randomly assigned to receive 3000, 3750, or 4500 mg/d (cohort B). The primary outcome measure was the control rate for predialysis serum phosphorus levels at the end of week 8, among patients in cohort B.

Results: At the end of week 4, 54% of patients achieved serum phosphorus control at dosages ≤3000 mg/d administered as one tablet per meal. Among patients who entered cohort B, control rates of 25, 38, and 32% for patients who were randomly assigned to 3000, 3750, or 4500 mg/d lanthanum carbonate, respectively, were achieved, with no increase in adverse events. Patients and physicians reported significantly higher levels of satisfaction with reformulated lanthanum carbonate compared with previous phosphate binders, partly because of reduced tablet burden with higher dosage strengths. Physicians and patients also expressed a preference for lanthanum carbonate over previous medication.

Conclusions: Reformulated lanthanum carbonate is an effective phosphate binder that may reduce daily tablet burden.

Feasibility and Impact of the Measurement of Extracellular Fluid Volume Simultaneous with GFR by 125I-Iothalamate

The feasibility, validity, and possible applications of the assessment of extracellular fluid volume (ECFV) simultaneous with glomerular filtration rate (GFR) were assessed in a series of validation studies using the constant infusion method of ¹²⁵I-iothalamate (IOT). In 48 subjects with a broad range of GFR, distribution volume (V_d) of IOT corresponded well with V_d bromide (16.71 ± 3.0 and 16.73 ± 3.2 l, respectively, not significant), with a strong correlation (r = 0.933, P < 0.01) and without systematic deviations. Reproducibility assessment in 25 healthy male subjects showed coefficients of variation of 8.6% of duplicate measurement of V_d IOT during strictly standardized (50 mmol Na⁺/d) sodium intake. An increase in dietary sodium intake (200 mmol Na⁺/d) induced a corresponding rise in V_d IOT of 1.11 ± 1.5 l (P < 0.01). In 158 healthy prospective kidney donors, the impact of indexing of GFR to ECFV was analyzed. Age, gender, height, and body surface area (BSA) were determinants of GFR. Whereas GFR, GFR/BSA, and GFR/height were gender-dependent, GFR/ECFV was gender-independent and not related to height or BSA. This supports the potential of normalizing GFR by ECFV. Thus, ECFV can be simultaneously assessed with GFR by the constant infusion method using IOT. After appropriate validation, also other GFR tracers could be used for such a simultaneous estimation, providing a valuable resource of data on ECFV in renal studies and, moreover, allowing GFR to be indexed to the body fluid compartment it clears: the ECFV.

Associations of Kidney Function with Cardiovascular Medication Use after Myocardial Infarction

Background and objectives: It is unknown whether adherence to recommended medications after myocardial infarction (MI) differs by kidney function.

Design, setting, participants, & measurements: This was a retrospective cohort study of older patients who were discharged after MI in two Eastern states between 1995 and 2004. Patients were categorized as having ESRD, having chronic kidney disease (CKD), and being free from diagnosed CKD. Use of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers (ACEI/ARB), β blockers (BB), and statins was assessed within 30 d after discharge. Good adherence was defined as proportion of days covered >80% during the first year after discharge.

Results: Compared with patients with no CKD, patients with CKD had 22% lower adjusted use of ACEI/ARB but similar rates of BB and statin use. Patients with ESRD experienced 43% lower ACEI/ARB and 17% lower statin use. Only 64% (BB), 57% (statins), and 54% (ACEI/ARB) of patients had good 1-yr adherence. Adherence was similar between patients with CKD and with no CKD for all study drugs. Fewer patients with ESRD had good adherence to BB.

Conclusions: With the exception of lower ACEI/ARB use in patients with CKD, we found no differences between patients with CKD and with no CKD in their use of and adherence to these cardiovascular medications after MI. Patients with ESRD experienced lower use of ACEI/ARB and statins and lower adherence to BB regimens. Postulated differences in medication use after MI across levels of kidney function are unlikely to explain the observed differences in long-term outcomes.

Cause-specific Mortality of Dialysis Patients After Coronary Revascularization: Why Don't Dialysis Patients Have Better Survival After Coronary Intervention?

Why is mortality risk after coronary intervention significantly higher for dialysis patients? Authors of this retrospective review share study results and suggest strategies to improve the problem.
Nephrology Dialysis Transplantation

Genetic data stored at NIH temporarily withdrawn due to privacy concerns raised by new method of forensic SNP analysis

New Scientist: Participants in such "genome-wide association" studies have been told that it was impossible to gain any information about individuals from these summary statistics. So after being informed about Craig's method, the NIH last week decided to remove summary data from its genome-wide association studies from the web (see the NIH statement, pdf format). Britain's Wellcome Trust, and the Broad Institute in Cambridge, Massachusetts, also took steps to remove their summary data from public view. "NIH did the right thing in applying the precautionary principle," says Kathy Hudson, director of the Genetics and Public Policy Center in Washington DC.