Consistent Control of Mineral and Bone Disorder in Incident Hemodialysis Patients

Background and objectives: In 2003, the National Kidney Foundation introduced guidelines for the control of parathyroid hormone, calcium, and phosphorus in hemodialysis patients.

Design, setting, participants, & measurements: A cohort study was conducted of 22,937 incident hemodialysis patients who were identified from a large national provider between July 1, 2000, and June 30, 2002, and followed through June 30, 2004. Consistent achievement was determined (1) as the simultaneous control of multiple markers over time and (2) as the time in target for each marker during the first year of dialysis. Mortality risk was assessed with Cox proportional hazards models.

Results: In the simultaneous control analysis, patients who achieved target for none of the markers had a 51% greater risk for death than those who achieved target for all three markers (reference group). Patients who achieved any target for any single marker had a 35 to 39% higher risk for death, and patients who achieved target for any two of the three markers had a 15 to 21% higher risk for death compared with the reference group. In the time in target analysis, patients with parathyroid hormone in target for 4 quarters had a 25% lower risk for death compared with those who did so for ≤1 quarter (reference group). Patients with calcium in target for 4 quarters had a 14% lower risk, and patients with phosphorus in target for 4 quarters had a 38% lower risk.

Conclusions: Consistent control of the markers of bone metabolism and disease within published targets is a strong predictor of survival in hemodialysis patients.

Incidence and Outcomes of Contrast-Induced AKI Following Computed Tomography

Background and objectives: Most studies of contrast-induced acute kidney injury (CIAKI) have focused on patients undergoing angiographic procedures. The incidence and outcomes of CIAKI in patients undergoing nonemergent, contrast-enhanced computed tomography in the inpatient and outpatient setting were assessed.

Design, setting, participants, & measurements: Patients with estimated glomerular filtration rates (GFRs) <60 ml/min per 1.73 m² undergoing nonemergent computed tomography with intravenous iodinated radiocontrast at an academic VA Medical Center were prospectively identified. Serum creatinine was assessed 48 to 96 h postprocedure to quantify the incidence of CIAKI, and the need for postprocedure dialysis, hospital admission, and 30-d mortality was tracked to examine the associations of CIAKI with these medical outcomes.

Results: A total of 421 patients with a median estimated GFR of 53 ml/min per 1.73 m² were enrolled. Overall, 6.5% of patients developed an increase in serum creatinine ≥25%, and 3.5% demonstrated a rise in serum creatinine ≥0.5 mg/dl. Although only 6% of outpatients received preprocedure and postprocedure intravenous fluid, <1% of outpatients with estimated GFRs >45 ml/min per 1.73 m² manifested an increase in serum creatinine ≥0.5 mg/dl. None of the study participants required postprocedure dialysis. Forty-six patients (10.9%) were hospitalized and 10 (2.4%) died by 30-d follow-up; however, CIAKI was not associated with these outcomes.

Conclusions: Clinically significant CIAKI following nonemergent computed tomography is uncommon among outpatients with mild baseline kidney disease. These findings have important implications for providers ordering and performing computed tomography and for future clinical trials of CIAKI.

Diagnosing Hypertension by Intradialytic Blood Pressure Recordings

Background and objectives: The diagnosis of hypertension among hemodialysis patients by predialysis or postdialysis blood pressure (BP) recordings is imprecise and biased and has poor test-retest reliability. The use of intradialytic BP measurements to diagnose hypertension is unknown.

Design, setting, participants, & measurements: A diagnostic-test study was done with interdialytic ambulatory BP as reference standard. Index BP recordings tested were: predialysis (method 1), postdialysis (method 2), intradialytic (method 3), intradialytic including predialyis and postdialysis (method 4), and the average of predialysis and postdialysis (method 5). Each index BP was recorded over six consecutive dialysis treatments.

Results: There were differences among index BP measurements in reproducibility, bias, precision, and accuracy. Method 4 was the most reproducible (intraclass correlation coefficient = 0.70 for systolic and diastolic BP). All 5 measurement methods overestimated 44-h ambulatory systolic BP. Methods 2, 3, or 4 overestimated ambulatory systolic BP by only a small amount. Method 4 was the most precise and accurate. For diagnosis of hypertension, BP cut-point by method 4 of 135/75 mmHg, had a sensitivity of 90.4% and specificity of 75.9% for systolic BP (area under ROC curve 0.90). Median cut-off systolic BP of 140 mmHg from a single dialysis provides approximately 80% sensitivity and 80% specificity in diagnosing systolic hypertension; a median cut-off diastolic BP of 80 mmHg provides approximately 75% sensitivity and 75% specificity in diagnosing diastolic hypertension.

Conclusions: Consideration of intradialytic BP measurements together with predialysis and postdialysis BP measurements improves the reproducibility, bias, precision, and accuracy of BP measurement compared with predialysis or postdialysis measurements.

Effect of Tonsillectomy Plus Steroid Pulse Therapy on Clinical Remission of IgA Nephropathy: A Controlled Study

Background and objectives: Few well-designed investigations have examined how tonsillectomy plus steroid pulse therapy affects IgA nephropathy. A prospective, controlled study therefore was performed to compare the effects of combined therapy with those of steroid pulse alone in patients with IgA nephropathy.

Design, setting, participants, & measurements: Fifty-five patients were followed up for 54.0 ± 21.2 mo. Thirty-five of them underwent tonsillectomy and steroid pulse therapy (group C), and 20 received steroid pulse monotherapy (group M). Both groups received methylprednisolone intravenously, followed by oral prednisolone (initial dosage 0.5 mg/kg per d) for 12 to 18 mo. Primary evaluation items were a 100% increase in serum creatinine from baseline levels or the disappearance of urinary protein (UP) and/or occult blood (UOB) indicating clinical remission.

Results: At 24 mo after the initial treatment, the ratios of the UP and UOB disappearance were higher in group C than in group M, and the therapeutic effect persisted until the final observation. None of group C achieved a 100% increase in serum creatinine from the baseline level, whereas one patient in group M developed ESRD during the observation period. The histologic findings of repeated biopsy specimens from 18 patients revealed that mesangial proliferation and IgA deposition were significantly more reduced in group C than in group M. The Cox regression model showed that the combined therapy was approximately six-fold more effective in causing the disappearance of UP than steroid pulse monotherapy.

Conclusion: Tonsillectomy combined with steroid pulse treatment can induce clinical remission in patients with IgA nephropathy.

Orally administered tetrahydrobiopterin can reduce hypertension

Orally administered tetrahydrobiopterin can reduce hypertension

Nature Clinical Practice Nephrology 4, 465 (2008). doi:10.1038/ncpneph0884