			Home About us Contact

Multicenter Clinical Trials (multicenter + clinical_trials)

Distribution by Scientific Domains

Medical Sciences	100%

Selected Abstracts

Search for the Optimal Right Ventricular Pacing Site: Design and Implementation of Three Randomized Multicenter Clinical Trials

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 4 2009
GERRY KAYE M.D.
Background: The optimal site to permanently pace the right ventricle (RV) has yet to be determined. To address this issue, three randomized prospective multicenter clinical trials are in progress comparing the long-term effects of RV apical versus septal pacing on left ventricular (LV) function. The three trials are Optimize RV Selective Site Pacing Clinical Trial (Optimize RV), Right Ventricular Apical and High Septal Pacing to Preserve Left Ventricular Function (Protect Pace), and Right Ventricular Apical versus Septal Pacing (RASP). Methods: Patients that require frequent or continuous ventricular pacing are randomized to RV apical or septal pacing. Optimize RV excludes patients with LV ejection fraction <40% prior to implantation, whereas the other trials include patients regardless of baseline LV systolic function. The RV septal lead is positioned in the mid-septum in Optimize RV, the high septum in Protect Pace, and the mid-septal inflow tract in RASP. Lead position is confirmed by fluoroscopy in two planes and adjudicated by a blinded panel. The combined trials will follow approximately 800 patients for up to 3 years. Results: The primary outcome in each trial is LV ejection fraction evaluated by radionuclide ventriculography or echocardiography. Secondary outcomes include echo-based measurements of ventricular/atrial remodeling, 6-minute hall walk distance, brain natriuretic peptide levels, and clinical events (atrial tachyarrhythmias, heart failure, stroke, or death). Conclusion: These selective site ventricular pacing trials should provide evidence of the importance of RV pacing site in the long-term preservation of LV function in patients that require ventricular pacing and help to clarify the optimal RV pacing site. [source]

Variation in Institutional Review Board Responses to a Standard Protocol for a Multicenter Clinical Trial

ACADEMIC EMERGENCY MEDICINE, Issue 6 2001
Thomas O. Stair MD
Abstract. Multicenter clinical trials require approval by multiple local institutional review boards (IRBs). The Multicenter Airway Research Collaboration mailed a clinical trial protocol to its U.S. investigators and 44 IRBs ultimately reviewed it. Objective: To describe IRB responses to one standard protocol and thereby gain insight into the advantages and disadvantages of local IRB review. Methods: Two surveys were mailed to participants, with telephone follow-up of nonrespondents. Survey 1 was mailed to 82 investigators across North America. Survey 2 was mailed to investigators from 44 medical centers in 17 U.S. states. Survey 1 asked about each investigator's local IRB (e.g., frequency of meetings, membership), whereas survey 2 asked about IRB queries and concerns related to the submitted clinical trial. Results: Both surveys had 100% response rate. Investigators submitted applications a median of 58 days (interquartile range [IQR], 40-83) after receipt of the protocol, and IRB approval took an additional 38 days (IQR, 26-62). Although eight applications were approved with little or no changes, IRBs requested an average of 3.5 changes per site. Changes involved study logistics and supervision for 45%, the research process for 43%, and the consent form for 91%. Despite these numerous requests, all eventually approved the basic protocol, including inclusion criteria, intervention, and data collection. Conclusions: The IRBs showed extreme variability in their initial responses to a standard protocol, but ultimately all gave approval. Almost all IRBs changed the consent form. A national, multicenter IRB process might streamline ethical review and warrants further consideration. [source]

Urodynamic standardization in a large-scale, multicenter clinical trial examining the effects of daily tadalafil in men with lower urinary tract symptoms with or without benign prostatic obstruction,

NEUROUROLOGY AND URODYNAMICS, Issue 5 2010
Stephen R. Kraus
Abstract Aims To present the methodology, standardization techniques, and results from post hoc test,retest reproducibility analyses for a large, placebo-controlled, multicenter trial, employing urodynamic studies (UDS) to assess the impact of daily tadalafil on men with lower urinary tract symptoms (LUTS) with or without benign prostatic obstruction (BPO). Methods UDS implemented International Continence Society (ICS) Good Urodynamic Practice guidelines and standardized urodynamic and LUTS terminology. Further standardization procedures included: equipment calibration; a detailed procedure manual and centralized training; and implementation of a central reader. Measures included: monitoring of invalid studies, comparison of actual versus expected standard deviation (SD) for primary outcome (detrusor pressure at maximum urinary flow rate [pdetQmax]), and test,retest reproducibility of the placebo arm at baseline and endpoint. Results Two hundred men with moderate to severe LUTS (baseline IPSS ,13) at 20 sites were randomized to receive either tadalafil 20,mg or placebo. All men underwent non-invasive uroflow and pressure-flow studies. Numbers of invalid studies at baseline and endpoint were 9.3% and 0.6%, respectively. Variability of pdetQmax was lower than anticipated based on actual versus expected SD of 15 and 30, respectively. Correlation coefficients were very good for pressure-flow parameters including pdetQmax (r,=,.83). Conclusions Multicenter clinical trials using urodynamic outcomes require additional standardized procedures to limit inter-site variability. By implementing centralized training with a detailed procedure manual and use of a central reader, we were able to limit common difficulties arising in multicenter clinical trials, as well as demonstrate good test,retest reproducibility of pressure flow measures. Neurourol. Urodynam. 29:741,747, 2010. © 2010 Wiley-Liss, Inc. [source]

Ribavirin dosage in patients with HCV genotypes 2 and 3 who completed short therapy with peg-interferon ,-2b and ribavirin

ALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 12 2010
A. MANGIA
Aliment Pharmacol Ther,31, 1346,1353 Summary Background, The optimal dose of ribavirin to be used in combination with Peg-IFN in patients with HCV genotypes 2 and 3 undergoing short treatment has not been established. Aim, To explore the relationship between starting ribavirin doses, expressed as mg/kg body weight and both rapid viral response at treatment week 4 (RVR) and sustained virological response (SVR) in patients treated for 12,14 weeks with peg-interferon ,-2b and ribavirin. Methods, A post hoc analysis of data collected from two multicenter clinical trials was performed. Multiple regression analyses were employed to identify independent baseline and on-treatment predictors of RVR and SVR. For each dose of ribavirin, the empirical estimated probability of response was computed and the continuous exposure index was dichotomized by using a recursive partitioning and amalgamation method. Results, A nonlinear relationship was ascertained between ribavirin dose and RVR, but not SVR. A dose of 15.2 mg/kg was selected as the best splitting value for discriminating RVR vs. non-RVR. Regression analysis identified low baseline viraemia, genotype 2 and high ribavirin dose as independent prognostic factors for RVR. The likelihood of an SVR was not correlated with baseline ribavirin dose, but was independently predicted by adherence to the full dose throughout treatment and normal platelet counts. Conclusions, Starting high ribavirin doses appears capable of increasing the rate of RVR in patients with HCV genotypes 2 and 3 undergoing short treatment. Maintenance of the full planned dose throughout treatment is essential for achieving optimal SVR rates. [source]

Urodynamic standardization in a large-scale, multicenter clinical trial examining the effects of daily tadalafil in men with lower urinary tract symptoms with or without benign prostatic obstruction,

Search for the Optimal Right Ventricular Pacing Site: Design and Implementation of Three Randomized Multicenter Clinical Trials

Recombinant human erythropoietin in pediatric oncology: A review,

PEDIATRIC BLOOD & CANCER, Issue 4 2002
James Feusner MD
Abstract Background Numerous reports on recombinant human erythropoietin (rHuEPO, epoetin alfa) treatment of cancer-related anemia in adult patients have been published to date. These have shown that epoetin increases hemoglobin levels, significantly ameliorates symptoms of anemia, and improves adult patients' quality of life. Unfortunately, less is known about the impact of epoetin on anemia in pediatric cancer patients. Procedure It is the objective of this review to summarize and analyze data of clinical trials of epoetin treatment of anemia in pediatric cancer patients. Results A total of 15 studies were reviewed; eight were considered for detailed analysis and demonstrated important variabilities in study methods. Four of the eight were controlled, randomized trials and four were open label. Conclusions These studies suggested an overall beneficial effect of epoetin alfa for treating anemia in children with cancer. Three large, multicenter clinical trials of the efficacy and safety of epoetin alfa in anemic children with cancer are currently underway, one in Europe and two in North America. Med Pediatr Oncol 2002; 39:463,468. © 2002 Wiley-Liss, Inc. [source]

Protocol Biopsies in Renal Transplantation: Insights into Patient Management and Pathogenesis

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 3 2007
M. Mengel
A 1-day symposium on the application of protocol biopsies in renal transplantation was held in Boston, 21 July 2006. Representatives from centers with extensive experience in the use of protocol biopsies for routine patient care and research reported results on the pathological findings and their value in patient management. The consensus was that protocol biopsies, in experienced hands, are a safe and valuable means of detecting subclinical disease that can benefit from modification of therapy. Furthermore, molecular studies reveal evidence of activity or progression not readily appreciated by histological techniques. Wider application is expected in multicenter clinical trials to predict and validate outcomes. The principal barrier to wider use of protocol biopsies is knowledge of the benefits of intervention. [source]

Lack of agreement between rheumatologists in defining digital ulceration in systemic sclerosis

ARTHRITIS & RHEUMATISM, Issue 3 2009
Ariane L. Herrick
Objective To test the intra- and interobserver variability, among clinicians with an interest in systemic sclerosis (SSc), in defining digital ulcers. Methods Thirty-five images of finger lesions, incorporating a wide range of abnormalities at different sites, were duplicated, yielding a data set of 70 images. Physicians with an interest in SSc were invited to take part in the Web-based study, which involved looking through the images in a random sequence. The sequence differed for individual participants and prevented cross-checking with previous images. Participants were asked to grade each image as depicting "ulcer" or "no ulcer," and if "ulcer," then either "inactive" or "active." Images of a range of exemplar lesions were available for reference purposes while participants viewed the test images. Intrarater reliability was assessed using a weighted kappa coefficient with quadratic weights. Interrater reliability was estimated using a multirater weighted kappa coefficient. Results Fifty individuals (most of them rheumatologists) from 15 countries participated in the study. There was a high level of intrarater reliability, with a mean weighted kappa value of 0.81 (95% confidence interval [95% CI] 0.77, 0.84). Interrater reliability was poorer (weighted , = 0.46 [95% CI 0.35, 0.57]). Conclusion The poor interrater reliability suggests that if digital ulceration is to be used as an end point in multicenter clinical trials of SSc, then strict definitions must be developed. The present investigation also demonstrates the feasibility of Web-based studies, for which large numbers of participants can be recruited over a short time frame. [source]