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PubMed1993

Multicenter study with recombinant human erythropoietin.

A multicenter study with recombinant human erythropoietin (rh-EPO) was carried out. Of 172 hemodialysis patients with anemia selected for the study from 20 hospitals and clinics, 77 were males and 95 females (mean age 53.9 years). A starting dose of 1,500 U of rh-EPO (Epoetin beta) was administered intravenously at the end of every dialysis session. If the efficacy was not acceptable, the dose was increased to 3,000 U. When the target hematocrit was achieved (30%), the total dose was decreased. The results of the study were excellent relative to those of other multicenter studies with regard to efficacy, safety, and changes in laboratory data. The incidence of hypertension was lower in our study compared with other reports because we used a low initial dose. The efficacy of rh-EPO therapy was determined earlier and more reliably by reticulocytes than by hematocrit or hemoglobin. Prompt iron supplement therapy is recommended with careful observation of serum iron and ferritin.

Anemia↗

PubMed2000

Interrater reliability of the Clinical Dementia Rating in a multicenter trial.

OBJECTIVE: To test the interrater reliability of the Clinical Dementia Rating (CDR) in a multicenter clinical trial. DESIGN: Observational study. SETTING: Training session for a multicenter trial of milameline, a direct muscarinic agonist, in the treatment of Alzheimer's disease. PARTICIPANTS: Twenty-four raters (physicians and nurses) familiar with drug trials and expert in the care of patients with Alzheimer's disease. METHODS: Independent scoring of the CDR using four videotaped CDR interviews. OUTCOME MEASURE: Interrater reliability, as tested by the Kappa statistic RESULTS: The overall interrater reliability was 0.62. Within the CDR domains, the global kappas ranged from 0.33 +/- 0.06 to 0.88 +/- 0.06. CONCLUSIONS: The data support moderate to high overall interrater reliability but show important difficulties in the reliable assessment of early dementia.

Dementia↗

PubMed1995

Termination and acceleration of ventricular tachycardia with autodecremental pacing, burst pacing, and cardioversion in patients with an implantable cardioverter defibrillator. Multicenter PCD Investigator Group.

This multicenter study reports the outcome of ventricular tachycardia (VT) therapy (conversion or acceleration) and the relationship to initial tachycardia cycle length and other clinical variables using an implantable device with the capability of autodecremental or burst pacing, cardioversion, and defibrillation. The device was implanted in 444 patients (mean age 58 +/- 15 years) with 1,240 episodes of VT induced with noninvasive programming and reported in a multicenter database. Only the first sequence attempted for conversion by pacing or cardioversion was assessed, and cardioversion energies were 0.2-5 J. Autodecremental pacing was used to treat 700 induced episodes of VT during titration of pacing therapies (57% converted and 12% accelerated), burst pacing to treat 357 episodes (49% converted under 11% accelerated), and cardioversion to treat 183 episodes (82% converted and 4% accelerated). Cardioversion was the most effective treatment and had the lowest acceleration rate. Shorter VT cycle lengths were more likely to accelerate with burst pacing and longer VT cycle lengths to convert with both burst and autodecremental pacing. Patients with higher ejection fractions were more likely to convert with autodecremental and burst pacing. Use of cardioversion, higher ejection fraction, absence of unrepaired aneurysm, longer VT cycle lengths, coronary artery disease, and use of autodecremental pacing predicted conversion. Lower ejection fraction and VT cycle lengths < or = 300 msec predicted tachycardia acceleration.

Adult↗

PubMed2006

The reliability of echocardiographic left ventricular wall motion index to identify high-risk patients for multicenter studies.

OBJECTIVE: To study whether the use of echocardiographic left ventricular (LV) wall motion index (WMI) is a dependable parameter for identifying patients with LV dysfunction to be enrolled in multicenter trials. METHODS: Videotaped echocardiographic examinations from 200 randomly selected patients that were screened for inclusion into the DIAMOND-CHF and DIAMOND-MI trials were reevaluated by an external expert echocardiographer. WMI was calculated using the 16-segment LV model. RESULTS: The external echocardiographer systematically found lower values of WMI than the core laboratory. The average difference in WMI was 0.18 (SD: 0.33) in the DIAMOND-CHF trial and 0.09 (SD: 0.33) in the DIAMOND-MI trial. The difference in WMI exceeded 0.33 in 34% of the patients in both trials. The cutoff value for inclusion into the DIAMOND trials was WMI < or = 1.2. There was an agreement on WMI dichotomized to below or above 1.2 in 82% of the patients in both trials (kappa coefficient 0.66 for the DIAMOND-CHF and 0.55 for the DIAMOND-MI). CONCLUSIONS: Despite substantial interlaboratory variation in WMI in individual patients and a systematic lower WMI score by the external echocardiographer there was an acceptable overall agreement for identifying patients with severe impairment of LV function. This not only underscores the value of LV-WMI as a useful tool for selecting high-risk patients to be included in multicenter studies but also serves to warn against the use of rigid cutoff values for WMI in the treatment of individual patients.

Anti-Arrhythmia Agents↗

PubMed2000

Standardization of a simplified scintigraphic methodology for the assessment of gastric emptying in a multicenter setting.

OBJECTIVE: Scintigraphy remains the gold standard to study gastric emptying. The technique is onerous and normal values vary between centers. Standardized protocols, although desirable, are not presently available. We validated a simplified scintigraphic protocol in a multicenter setting. METHODS: In 69 healthy volunteers from seven Canadian institutions, gastric emptying of a standard meal (99mTc-labeled beef liver) was assessed by scintigraphy every 10 min for 1 h, then every 20 min for the next 2 h. Gastric retention was fitted to a power exponential model, Prop(t) = (-(kappat)beta) with Prop(t) = proportion of retention at time t, either using all 13 time intervals (conventional technique) or using measurements at 0, 1, 2, and 3 h (simplified technique). RESULTS: The power exponential model yielded identical emptying curves and T 1/2 values with both techniques. Gastric emptying was more rapid in men than in women < 35 yr (p<0.01) and in younger than in older men (p<0.005). Gastric emptying was slower in women from Québec than in women from Ontario (p<0.04). Gastric retention was similar at 1, 2, and 3 h among the seven centers. Gastric emptying of a beef liver meal was slower than that of a low fat egg substitute (p<0.03). CONCLUSIONS: A simpler scintigraphic approach, using four rather than 13 samples, provides results comparable to those of the conventional technique. This simpler approach provides an economical, yet accurate, alternative to the techniques presently used and is applicable to a multicenter setting.

Adult↗

PubMed2004

Enterocyte actin autoantibody detection: a new diagnostic tool in celiac disease diagnosis: results of a multicenter study.

OBJECTIVES: This study describes a new method to detect autoantibodies against actin filaments (AAA) as a serological marker of intestinal villous atrophy (IVA) in celiac disease (CD), and reports the results of an Italian double-blind multicenter study. METHODS: IgA-AAA were analyzed by immunofluorescence using a newly developed method based on intestinal epithelial cells cultured in presence of colchicine. IgA-AAA were blindly evaluated prospectively in 223 antiendomysial antibody (AEA) and/or antitransglutaminase antibody (TGA) positive subjects and in 78 AEA and TGA negative subjects. IgA-AAA positive patients underwent an intestinal biopsy to confirm the diagnosis. Moreover, IgA-AAA were retrospectively investigated in 84 biopsy-proven CD patients and in 2,000 new consecutively collected serum samples from AEA and TGA negative nonbiopsied subjects. RESULTS: IgA-AAA were positive in 98.2% of the CD patients with flat mucosa, in 89% with subtotal villous atrophy, and in 30% with partial villous atrophy. IgA-AAA were present in none of the AEA and TGA negative nonbiopsied controls. In AEA and/or TGA positive CD patients IgA-AAA positivity significantly correlated with IVA (p < 0.000 in the prospective study, p = 0.005 in the retrospective study). In the prospective study, the values of sensitivity, specificity, the positive predictive value, the negative predictive value, and the efficiency of the IgA-AAA test to identify patients with IVA were, respectively, 83.9%, 95.1%, 97.8%, 69.2%, and 87.0%. Furthermore, a significant correlation (p < 0.0001) was found between the IgA-AAA serum titre and the degree of IVA (rs 0.56). CONCLUSIONS: The results of this multicenter study show that the new method for IgA-AAA detection could represent a practical diagnostic tool in AEA and/or TGA positive subjects, which would be especially useful when IVA shows a patchy distribution, when the histological picture is difficult to interpret, or when a biopsy could represent a life-threatening risk.

Actins↗

PubMed2006

Ablation of nonneoplastic Barrett's mucosa using argon plasma coagulation with concomitant esomeprazole therapy (APBANEX): a prospective multicenter evaluation.

BACKGROUND: Complete reversal of Barrett's epithelium (BE) achieved by treatment with argon plasma coagulation (APC) is variable. The aim of this prospective study was to evaluate the effectiveness of high-power APC in a multicenter trial. METHODS: In seven study centers, 60 patients (mean age 57, range 27-77) with nonneoplastic BE (length 1-8 cm) were recruited for treatment with high-power APC (90 W) in combination with esomeprazole 80 mg/day. Video endoscopy, chromoendoscopy, and four-quadrant biopsies (4QB) were carried out during baseline endoscopy and regular intervals. The effect of ablation was classified as complete remission (CR), partial remission, or minor response. RESULTS: Fifty-one of the 60 patients completed ablation therapy. Three patients were lost to follow-up (FU). After a mean of 2.6 APC sessions (range 1-5) and a mean FU of 14 months (range 12-32), CR was achieved in 37 of 48 patients (77%). Major complications occurred in five of 51 patients (9.8%). CONCLUSIONS: Complete ablation of BE can be achieved in a high percentage of patients even in a multicenter design using high-power APC. However, APC has a relevant morbidity. Therefore, ablation of nonneoplastic BE cannot be recommended generally because incidence of cancer in BE is low.

Adult↗

PubMed1996

Efficacy of quantitative digital subtraction radiography using radiographs exposed in a multicenter trial.

Digital subtraction radiography (DSR) has been shown to be a sensitive and specific method for the detection of small bony changes in periodontitis. The purpose of this study was to perform a multicenter validation of the DSR in human subjects. Seventeen subjects were enrolled at 3 centers. Feather-edged hydroxyapatite chips (approximately 1, 7 and 10 mg) were used to simulate osseous lesions. Bilateral radiographs were taken with and without chips. Geometry was standardized using a cephalostat and the order of radiographs was determined using a randomization plan. Radiographs were subtracted, lesions isolated, and quantified at a single center without knowledge of the randomization code or location of the chips used in each subject. The overall sensitivity and specificity in detecting 1 mg changes was 87.8% and 100%, respectively. Sensitivity and specificity in detecting 7 mg and 10 mg chips was 100%. A strong linear relationship between actual lesion mass and calculated mass was observed (R2 = 0.94, slope = 0.98, p < 0.0001). No significant differences were observed by center. These data indicate that the DSR is a valid technique for the assessment of alveolar bone changes in multicenter trials.

Adult↗

PubMed2006

Mycophenolate mofetil reduces intimal thickness by intravascular ultrasound after heart transplant: reanalysis of the multicenter trial.

UNLABELLED: The mycophenolate mofetil (MMF) trial involved 650 heart transplant patients from 28 centers who received MMF or azathioprine (AZA), both in combination with cyclosporine and corticosteroids. Baseline and 1-year intravascular ultrasound (IVUS) were performed in 196 patients (102 MMF and 94 AZA) with no differences between groups in IVUS results analyzed by morphometric analysis (average of 10 evenly spaced sites, without matching sites between studies). Baseline to first-year IVUS data can also be analyzed by site-to-site analysis (matching sites between studies), which has been reported to be more clinically relevant. Therefore, we used site-to-site analysis to reanalyze the multicenter MMF IVUS data. RESULTS: IVUS images were reviewed and interpretable in 190 patients (99 MMF and 91 AZA) from the multicenter randomized trial. The AZA group compared to the MMF group had a larger number of patients with first-year maximal intimal thickness (MIT)>or=0.3 mm (43% vs. 23%, p=0.005), a greater decrease in the mean lumen area (p=0.02) and a decrease in the mean vessel area (the area actually increased in the MMF group, p=0.03). CONCLUSION: MMF-treated heart transplant patients compared to AZA-treated patients, both concurrently on cyclosporine and corticosteroids, in this study have significantly less progression of first-year intimal thickening.

Adrenal Cortex Hormones↗

PubMed2005

A computed tomographic scan-derived customized surgical template and fixed prosthesis for flapless surgery and immediate loading of implants in fully edentulous maxillae: a prospective multicenter study.

BACKGROUND: Based on three-dimensional implant planning software for computed tomographic (CT) scan data, customized surgical templates and final dental prostheses could be designed to ensure high precision transfer of the implant treatment planning to the operative field and an immediate rigid splinting of the installed implants, respectively. PURPOSE: The aim of the present study was to (1) evaluate a concept including a treatment planning procedure based on CT scan images and a prefabricated fixed prosthetic reconstruction for immediate function in upper jaws using a flapless surgical technique and (2) validate the universality of this concept in a prospective multicenter clinical study. MATERIALS AND METHODS: Twenty-seven consecutive patients with edentulous maxillae were included. Treatments were performed according to the Teeth-in-an-Hour concept (Nobel Biocare AB, Göteborg, Sweden), which includes a CT scan-derived customized surgical template for flapless surgery and a prefabricated prosthetic suprastructure. RESULTS: All patients received their final prosthetic restoration immediately after implant placement, that is, both the surgery and the prosthesis insertion were completed within approximately 1 hour. In the 24 patients followed for 1 year, all prostheses and individual implants were recorded as stable. CONCLUSION: The present prospective multicenter study indicates that the prefabrication, on the basis of models derived from three-dimensional oral implant planning software, of both surgical templates for flapless surgery and dental prostheses for immediate loading is a very reliable treatment option. It is evident that the same approach could be used for staged surgery and in partial edentulism.

Adult↗

PubMed2026

Aquablation/AquaBeam Waterjet Therapy for Benign Prostatic Hyperplasia: Three-Year Functional and Ejaculatory Outcomes in a Multicenter Real-World Italian Cohort.

OBJECTIVE: To evaluate the 3-year functional outcomes of Aquablation/AquaBeam waterjet therapy for bladder outlet obstruction secondary to benign prostatic hyperplasia (BPH), with particular attention to urinary symptoms, quality of life, continence, ejaculatory function, and complications. METHODS: We performed a retrospective analysis of a prospectively maintained multicenter database including 218 consecutive men who underwent Aquablation/AquaBeam for symptomatic BPH between January 2019 and January 2022 at three referral centers. Functional outcomes assessed preoperatively and during follow-up included International Prostate Symptom Score (IPSS), IPSS quality-of-life item (IPSS-QoL), maximum urinary flow rate (Qmax), post-void residual urine (PVR), continence, and ejaculatory function. Median follow-up was 36 months. Ejaculatory preservation was evaluated only in patients with preserved antegrade ejaculation at baseline. RESULTS: Median age was 61 years (IQR 57-66), median prostate-specific antigen (PSA) was 2.52 ng/mL (IQR 0.40-21.60), and median prostate volume was 55 mL (IQR 40-73). Median operative time was 56 min, while median catheterization time and length of hospital stay were both 48 h. Functional improvements were evident from the 3-month follow-up and remained stable through 36 months. At 36 months, median IPSS improved to 5 and median Qmax to 18 mL/s. Median PSA changed modestly from 2.52 ng/mL at baseline to 2.75 ng/mL at 36 months. No cases of de novo urinary incontinence were observed throughout follow-up. Among patients with preserved antegrade ejaculation at baseline, 87% maintained antegrade ejaculation at 36 months. Most postoperative complications were minor (Clavien-Dindo grade I-II, 20.2%). One grade III rectal injury occurred (0.5%). Median hemoglobin decreased from 15.2 g/dL preoperatively to 14.0 g/dL before hospital discharge, and two patients required blood transfusion. During the 36-month follow-up, no surgical retreatment was required, whereas 11 patients (5.0%) received temporary medical retreatment. CONCLUSION: In this multicenter real-world cohort, Aquablation/AquaBeam was safe and effective over 3 years, providing durable improvement in lower urinary tract symptoms and quality of life while preserving continence and antegrade ejaculation in most patients. These findings support Aquablation/AquaBeam as a valuable minimally invasive surgical option for selected men with BPH, particularly those who prioritize preservation of ejaculatory function. Longer-term and comparative studies are warranted. TRIAL REGISTRATION: 48281.

Humans↗

PubMed2000

Preservation of lymphocyte immunophenotype and proliferative responses in cryopreserved peripheral blood mononuclear cells from human immunodeficiency virus type 1-infected donors: implications for multicenter clinical trials. The ACTG Immunology Advanced Technology Laboratories.

Human immunodeficiency virus type 1 (HIV-1) infection results in impaired immune function that can be measured by changes in immunophenotypically defined lymphocyte subsets and other in vitro functional assays. These in vitro assays may also serve as early indicators of efficacy when new therapeutic strategies for HIV-1 infection are being evaluated. However, the use of in vitro assays of immune function in multicenter clinical trials has been hindered by their need to be performed on fresh specimens. We assessed the feasibility of using cryopreserved peripheral blood mononuclear cells (PBMC) for lymphocyte immunophenotyping and for lymphocyte proliferation at nine laboratories. In HIV-1-infected patients with moderate CD4(+) lymphocyte loss, the procedures of density gradient isolation, cryopreservation, and thawing of PBMC resulted in significant loss of CD19(+) B cells but no measurable loss of total T cells or CD4(+) or CD8(+) T cells. No significant changes were seen in CD28(-) CD95(+) lymphocytes after cell isolation and cryopreservation. However, small decreases in HLA-DR(+) CD38(+) lymphocytes and of CD45RA(+) CD62L(+) were observed within both the CD4(+) and CD8(+) subsets. Fewer than 10% of those specimens that showed positive PBMC proliferative responses to mitogens or microbial antigens lost their responsiveness after cryopreservation. These results support the feasibility of cryopreserving PBMC for immunophenotyping and functional testing in multicenter AIDS clinical trials. However, small changes in selected lymphocyte subsets that may occur after PBMC isolation and cryopreservation will need to be assessed and considered in the design of each clinical trial.

ADP-ribosyl Cyclase↗

PubMed1992

Standardization of sensitive human immunodeficiency virus coculture procedures and establishment of a multicenter quality assurance program for the AIDS Clinical Trials Group. The NIH/NIAID/DAIDS/ACTG Virology Laboratories.

An independent quality assurance program has been established by the Division of AIDS, National Institute of Allergy and Infectious Diseases, for monitoring virologic assays performed by nearly 40 laboratories participating in multicenter clinical trials in the United States. Since virologic endpoints are important in evaluating the timing and efficacy of therapeutic interventions, it is imperative that virologic measurements be accurate and uniform. When the quality assurance program was initially created, fewer than 40% of the laboratories could consistently recover human immunodeficiency virus (HIV) from peripheral blood mononuclear cells (PBMCs) of HIV-infected patients. By comparing coculture procedures in the more competent laboratories with those in laboratories who were struggling to isolate virus, optimal conditions were established and nonessential reagents and practices were eliminated. Changes were rapidly introduced into a laboratory when experience dictated that such modifications would result in a favorable outcome. Isolation of HIV was enhanced by optimizing the numbers and ratios of patient and donor cells used in cultures, by standardizing PBMC separation procedures, by using fresh rather than frozen donor PBMCs, by processing whole blood within 24 h, and by using natural delectinated interleukin 2 instead of recombinant interleukin 2 products in existence at that time. Delays of more than 8 h in the addition of phytohemagglutinin-stimulated donor cells to freshly separated patient PBMCs reduced recovery. Phytohemagglutinin in cocultures and the addition of Polybrene and anti-human alpha interferon to media were not important in HIV isolation. The introduction of a consensus protocol based on this information brought most laboratories quickly into compliance. In addition, monthly monitoring has successfully maintained proficiency among the laboratories, a process that is critical for the scientific integrity of collaborative multicenter trials. Problems which might not be appreciated for months are now being resolved early, before data can be compromised unknowingly. This consensus protocol is recommended for any laboratory attempting to isolate HIV for the purpose of standardizing recovery and for accessing virologic endpoints in clinical trials.

Culture Media↗

PubMed2002

Multicenter evaluation of a nonweekend reading schedule for radiometric pyrazinamide susceptibility testing of Mycobacterium tuberculosis.

Pyrazinamide (PZA) is an integral component of the short-course chemotherapy regimen for tuberculosis. The BACTEC 460TB PZA susceptibility test for Mycobacterium tuberculosis with a daily (D) reading schedule has been available for more than 10 years, but weekend laboratory staffing is necessary. A nonweekend (NW) reading schedule has not been validated in a multicenter study. This prospective multicenter study compares the interlaboratory reproducibility of PZA susceptibility results by following both the D and NW schedules. A total of 181 cultures were shared among four laboratories. Isolates were selected based on resistance or borderline resistance to at least one streptomycin-isoniazid-rifampin-ethambutol drug or PZA. One laboratory used a D reading schedule, and three laboratories used a NW schedule. Both reading schedules are based on the standard BACTEC 460TB PZA protocol. With the NW schedule, the growth index (GI) is not available for test interpretation on Saturday, Sunday, and Monday. Of the 181 shared cultures, 154 were found to be susceptible by all laboratories, 19 were found to be resistant, and 8 had discordant results. The overall pairwise interlaboratory agreement was 97.7%. The discrepancies were not associated with the type of reading schedule used. However, the median control GI was significantly higher for the NW schedule (321) than for the D schedule (259) (P < 0.0001) although results were available on average in about 7 days from setup for both schedules. These results show that the NW schedule is a suitable alternative for laboratories that do not read and interpret PZA susceptibility tests on weekends.

Antitubercular Agents↗

PubMed2025

Bacterial skin colonization with a specific Cutibacterium avidum clade as a risk factor for periprosthetic joint infections-a multicenter study.

Cutibacterium avidum is increasingly recognized as a causative agent of periprosthetic joint infections (PJIs), yet data on its pathogenic potential and distinguishing features from commensal strains remain limited. In this multicenter study, we compared 11 C. avidum isolates from PJIs with 32 isolates from healthy skin collected across four European hospitals. We investigated phylogenetic relationships, antibiotic susceptibility, biofilm formation, and bacterial fitness. Phylogenomic analysis revealed two main clades within the C. avidum population. All PJI isolates belonged exclusively to Clade 1, which also included skin isolates. Within Clade 1, gene content analysis showed no consistent genetic differences between PJI and skin isolates. All isolates exhibited moderate to strong biofilm formation, with no significant differences in either data set. Minimal inhibitory concentration (MIC) and minimal biofilm inhibitory concentration (MBIC) values were low and largely concordant, while minimal biofilm eradication concentration (MBEC) values were elevated for all antibiotics except rifampin. One isolate was resistant to clindamycin due to the erm(X) gene. Rifampin consistently showed the lowest MIC, minimal bactericidal concentration, MBIC, and MBEC values. Bacterial fitness, assessed via bacterial quantitative fitness analysis, was significantly lower in PJI isolates compared to skin isolates when all strains were analyzed (P = 0.039), but this difference was not statistically significant when restricted to Clade 1. In conclusion, C. avidum isolates are strong biofilm producers irrespective of clinical origin. PJI isolates are restricted to a single phylogenetic clade, yet lack distinct biofilm or fitness traits within that clade, suggesting that multiple Clade 1 strains may have the potential to cause PJIs. IMPORTANCE Cutibacterium avidum has long been considered a skin commensal, but it is increasingly associated with prosthetic joint infections (PJIs). Despite its clinical emergence, little is known about its virulence potential or how invasive strains differ from commensal ones. This multicenter study provides the most comprehensive comparative analysis to date, integrating phenotypic and genomic data from both PJI-associated and skin-derived isolates. We show that all isolates are strong biofilm formers and that invasive isolates exhibit reduced growth fitness-a phenotype linked to persistence and treatment failure in other pathogens. Notably, all PJI isolates belonged to a single phylogenetic clade, suggesting that specific lineages of C. avidum may be more likely to cause infection. These findings help clarify the biology of this emerging pathogen and provide a foundation for improved diagnostics, susceptibility testing, and future infection prevention and treatment strategies.

Biofilms↗

PubMedDate not supplied

Multicenter patient records research: security policies and tools.

The expanding health information infrastructure offers the promise of new medical knowledge drawn from patient records. Such promise will never be fulfilled, however, unless researchers first address policy issues regarding the rights and interests of both the patients and the institutions who hold their records. In this article, the authors analyze the interests of patients and institutions in light of public policy and institutional needs. They conclude that the multicenter study, with Institutional Review Board approval of each study at each site, protects the interests of both. "Anonymity" is no panacea, since patient records are so rich in information that they can never be truly anonymous. Researchers must earn and respect the trust of the public, as responsible stewards of facts about patients' lives. The authors find that computer security tools are needed to administer multicenter patient records studies and describe simple approaches that can be implemented using commercial database products.

Computer Security↗

PubMed1997

Multicenter trial validation of a camera-based method to measure Tc-99m mercaptoacetyltriglycine, or Tc-99m MAG3, clearance.

PURPOSE: To evaluate an improved camera-based method for calculating the clearance of technetium-99m mercaptoacetyltriglycine (MAG3) in a multicenter trial. MATERIALS AND METHODS: Tc-99m MAG3 scintigraphy was performed in 49 patients at three sites in the United States and Canada. The percentage of the injected dose of Tc-99m MAG3 in the kidney at 1-2, 1.0-2.5, and 2-3 minutes after injection was correlated with the plasma-based Tc-99m MAG3 clearances. The data were combined with the results obtained in 20 additional patients in a previously published pilot study. RESULTS: Regression models correlating the plasma-based Tc-99m MAG3 clearance with the percentage uptake in the kidney for each time interval were developed; there was no statistically significant difference among sites in the regression equations. Correction for body surface area statistically significantly (P < .005) improved the correlation coefficient for each time interval. For the 1.0-2.5-minute interval, the body surface area-corrected correlation coefficient for the four combined sites was .87, and it improved to .93 when one outlier was omitted from the analysis. Similar results were obtained with the other time intervals. Independent processing by two observers showed no clinically important differences in the percentage dose in the kidney or in relative function. CONCLUSION: An improved camera-based method to calculate the clearance of Tc-99m MAG3 was validated in a multicenter trial.

Adolescent↗

PubMed2000

Measurement of endometrial thickness at US in multicenter drug trials: value of central quality assurance reading.

PURPOSE: To assess the value of central quality assurance (QA) reading of transvaginal ultrasonographic (US) images obtained to measure endometrial thickness and to assess image quality. MATERIALS AND METHODS: Results of 2,000 US examinations performed in 1,000 subjects during one of two multicenter drug trials were evaluated. Endometrial thickness was measured at the study site; images were then sent to the QA center, where an experienced sonologist evaluated endometrial thickness and image quality. RESULTS: In 360 (18%) of the 2,000 examinations, image quality was insufficient for central QA reading. Repeat examinations were requested, and suggestions for improvement in technique were provided. In 349 (97%) of the 360 examinations, repeat US images were of acceptable quality. In 99 (5%) of the 1,989 examinations in which endometrial thickness was measured, central measurement of thickness differed by more than 2 mm from that of the site. In a group (n = 300) that was followed up for 1 year, requests for repeat US examinations decreased from 24% at baseline to 11% at 1 year. CONCLUSION: Central QA reading provides a consistent evaluation of endometrial thickness on US images obtained in multicenter drug trials and helps to ensure the acquisition of high-quality transvaginal US images. It further leads to demonstrable improvement in site performance.

Endometrium↗