Enhancing clinical trial development for pediatric kidney diseases.

The conduct of clinical trials in small pediatric subspecialties such as pediatric nephrology is hampered by both clinical demands on the pediatric nephrologist and the small number of appropriate patients available for such studies. The American Society of Pediatric Nephrology Therapeutics Development Committee (TDC) was established to (1) identify the various stakeholders with interests and/or expertise related to clinical trials in children with kidney disease and (2) develop more effective partnerships among all parties regarding strategies for successful clinical trial development and execution. This article discusses the rationale, structure, and function of the TDC, the status of progress toward its goals, and the insights gained to date that may be useful for other subspecialties that face similar challenges.

The pharmacokinetics and pharmacodynamics of PF-00734200, a DPP-IV inhibitor, in healthy Japanese subjects.

OBJECTIVE: To evaluate the pharmacokinetics, pharmacodynamics, safety, and tolerability of PF-00734200, a potent dipeptidyl peptidase-IV (DPP-IV) inhibitor, in Japanese subjects, and compare the results with those in Western subjects. MATERIALS AND METHODS: Eight healthy Japanese subjects received a single dose of PF-00734200 10 mg, 100 mg, or placebo. Another 8 subjects received PF-00734200 20 mg or placebo single dose once daily for 6 days. Serum and urine PK, plasma DPP-IV activity, and plasma glucagon-like peptide 1 (GLP-1) levels were measured. RESULTS: Linear pharmacokinetics was observed over the single dose range 10 - 100 mg. Following multiple-dose administration, 37.3 ± 4.33% of the unchanged PF-00734200 was excreted in the urine and renal clearance was calculated as 33.9 ± 6.56 ml/min. After the standardized meals, GLP- 1 levels increased ~ 2-fold compared with placebo, and no further increase in GLP-1 levels was observed at doses above 10 mg. The steady state DPP-IV inhibition at 24 h was ~ 75%. CONCLUSION: Pharmacokinetics of PF-00734200, inhibition of DPP-IV, and non-linear increases in GLP-1 were similar between healthy Japanese and Western subjects.

The Seattle Heart Failure Model: prediction of survival in heart failure.

BACKGROUND: Heart failure has an annual mortality rate ranging from 5% to 75%. The purpose of the study was to develop and validate a multivariate risk model to predict 1-, 2-, and 3-year survival in heart failure patients with the use of easily obtainable characteristics relating to clinical status, therapy (pharmacological as well as devices), and laboratory parameters. METHODS AND RESULTS: The Seattle Heart Failure Model was derived in a cohort of 1125 heart failure patients with the use of a multivariate Cox model. For medications and devices not available in the derivation database, hazard ratios were estimated from published literature. The model was prospectively validated in 5 additional cohorts totaling 9942 heart failure patients and 17,307 person-years of follow-up. The accuracy of the model was excellent, with predicted versus actual 1-year survival rates of 73.4% versus 74.3% in the derivation cohort and 90.5% versus 88.5%, 86.5% versus 86.5%, 83.8% versus 83.3%, 90.9% versus 91.0%, and 89.6% versus 86.7% in the 5 validation cohorts. For the lowest score, the 2-year survival was 92.8% compared with 88.7%, 77.8%, 58.1%, 29.5%, and 10.8% for scores of 0, 1, 2, 3, and 4, respectively. The overall receiver operating characteristic area under the curve was 0.729 (95% CI, 0.714 to 0.744). The model also allowed estimation of the benefit of adding medications or devices to an individual patient's therapeutic regimen. CONCLUSIONS: The Seattle Heart Failure Model provides an accurate estimate of 1-, 2-, and 3-year survival with the use of easily obtained clinical, pharmacological, device, and laboratory characteristics.

Diuretic resistance predicts mortality in patients with advanced heart failure.

BACKGROUND: In patients with chronic heart failure (CHF), diuretic requirements increase as the disease progresses. Because diuretic resistance can be overcome with escalating doses, the evaluation of CHF severity and prognosis may be incomplete without considering the intensity of therapy. METHODS: The prognostic importance of diuretic resistance (as evidenced by a high-dose requirement) was retrospectively evaluated in 1153 patients with advanced CHF who were enrolled in the Prospective Randomized Amlodipine Survival Evaluation (PRAISE). The relation of loop diuretic and angiotensin-converting enzyme inhibitor doses (defined by their median values) and other baseline characteristics to total and cause-specific mortality was determined by proportion hazards regression. RESULTS: High diuretic doses were independently associated with mortality, sudden death, and pump failure death (adjusted hazard ratios [HRs] 1.37 [P =.004], 1.39 [P =.042], and 1.51 [P =.034], respectively). Use of metolazone was an independent predictor of total mortality (adjusted HR = 1.37, P =.016) but not of cause-specific mortality. Low angiotensin-converting enzyme inhibitor dose was an independent predictor of pump failure death (adjusted HR = 2.21, P =.0005). Unadjusted mortality risks of congestion and its treatment were additive and comparable to those of established risk factors. CONCLUSIONS: The independent association of high diuretic doses with mortality suggests that diuretic resistance should be considered an indicator of prognosis in patients with chronic CHF. These retrospective observations do not establish harm or rule out a long-term benefit of diuretics in CHF, because selection bias may entirely explain the relation of prescribed therapy to death.

Importance of echocardiography in patients with severe nonischemic heart failure: the second Prospective Randomized Amlodipine Survival Evaluation (PRAISE-2) echocardiographic study.

BACKGROUND: Echocardiography is used commonly in clinical practice when caring for patients with heart failure. It is unknown whether the presence of certain findings provides an incremental ability to predict survival beyond the use of baseline clinical findings alone. The second PRAISE-2 echocardiographic study was prospectively designed to identify echocardiographic predictors of survival among patients with nonischemic cardiomyopathy and heart failure and to determine if components of the echocardiographic examination add prognostic information to baseline demographic and clinical information. METHODS: One hundred patients participated in the second Prospective Randomized Amlodipine Survival Evaluation Study (PRAISE-2) echocardiographic study; of these, 93 had full and interpretable echocardiographic examinations. Cox proportional hazards modeling was used to assess the relation between various characteristics and survival as well as to assess the incremental prognostic information gained by echocardiography beyond the clinical examination. RESULTS: Seven of 10 routine echocardiographic measures were significantly associated with death. These included mitral regurgitation (hazard ratio [HR], 2.31; 95% CI, 1.02, 5.27), left ventricular ejection fraction <20% (HR, 2.59; 95% CI, 1.14, 5.88), restrictive left ventricular filling pattern (HR, 2.37; 95% CI, 1.05, 5.32), and peak D velocity (HR, 1.62; 95% CI, 0.38, 0.87). The only statistically significant clinical predictor of survival was dyspnea at rest. The addition any of several echocardiographic parameters to baseline clinical information significantly improved the ability to predict survival. CONCLUSIONS: Several readily available echocardiographic parameters are predictive of death and when added to clinical examination findings significantly improve the ability to determine prognosis among patients with nonischemic cardiomyopathy and heart failure.

Should troponin and creatinine kinase be routinely measured after vascular surgery?

The current guidelines for the evaluation and prediction of adverse cardiovascular events (CVEs) following vascular surgery in high-risk patients recommends serial electrocardiograms (ECGs) but not biomarkers such as cTn-I and CK-MB. The objective of this study was to determine whether biomarkers should be routinely measured in high-risk patients undergoing vascular surgery. A multicenter, prospective study with investigators blinded to core laboratory results was conducted. cTn-I and CK-MB were obtained on the day of surgery, as well as 24 hours, 72 hours and 120 hours after surgery, 24 hours prior to planned hospital discharge and at the onset of symptoms of a suspected CVE. The CVE was adjudicated by an endpoint committee using ECG, biomarker and symptoms data and was defined as cardiac death or myocardial infarction (MI) occurring up to 30 days after surgery. A total of 784 patients, with a mean age of 70.1 (SD +/- 9.8), underwent vascular surgery. Of the 83 patients with a CVE, cTn-I was positive in 42 and CK-MB was positive in 29 on or before the day of the CVE. The number of patients not classified as having a CVE but positive for elevation of cTn-I or CK-MB was 64 and 20, respectively. cTn-I was more sensitive than CK-MB (50.6% versus 34.9%) for predicting a CVE. The optimum time for measuring cTn-I after surgery with the highest positive predictive value was 24 hours. In conclusion, these data support routine serial measurement of cTn-I after vascular surgery.

Efficacy of zoniporide, an Na/H exchange ion inhibitor, for reducing perioperative cardiovascular events in vascular surgery patients.

OBJECTIVES: To determine whether a novel Na+/H+ exchange ion inhibitor, zoniporide, is associated with reduced perioperative myocardial ischemic injury in high-risk surgery patients. DESIGN: Randomized double-blind placebo-controlled multidose trial. SETTING: Multicenter worldwide (105 centers) trial. PARTICIPANTS: Patients with known or multiple risk factors for coronary artery disease undergoing noncardiac vascular surgery. INTERVENTIONS: Four parallel groups received 1 of 3 doses of zoniporide or placebo, delivered as a 60-minute loading dose immediately before surgery, and followed by a continuous intravenous infusion for up to 7 days. MEASUREMENTS AND MAIN RESULTS: A total of 824 subjects were randomized into the study from 105 centers worldwide. Of these, 784 subjects received study drug infusion in the 3-mg/kg/d, 6-mg/kg/d, and 12-mg/kg/d groups and the placebo group, and 769 satisfied the criteria for the primary efficacy analysis population. This is 68% of the planned sample size of 1125 subjects. Anesthetic management and perioperative cardiac medications were at the discretion of the attending anesthesiologists, surgeons, and cardiologists. The proportion of subjects who experienced the composite endpoint event (death, myocardial infarction, congestive heart failure, arrhythmia) by postsurgical day 30 was 18.5% in the 12-mg/kg/d group, compared with 15.7% in the placebo group, resulting in a relative risk (RR) of 1.17% (95% confidence interval [CI], 0.80-1.72; p = NS) favoring placebo. The proportions in the lower 2 zoniporide dose groups were slightly lower than in the placebo group, although the sample size is inadequate to reach any firm conclusions. CONCLUSIONS: The results fail to demonstrate the efficacy of zoniporide in reducing the proportion of patients at high risk undergoing noncardiac vascular surgery who experience a composite cardiovascular endpoint, which led the corporate sponsor to stop enrollment early on the basis of a futility analysis of the chance of demonstrating efficacy with a larger sample size.