>>With cgtk, my concern is betting on a phase III based on 17 active patients in phase II. I also wonder what the real relevance is of 76% restenosis (failure) or 74% (success) and how easily minute differences can be measured? Could data be subject to bias? If 2 different groups did the measurements would you get two different outcomes (agix like?)? Do you trust the phase II data? <<
Well, the only thing I saw was the hazard ratio of .34 wtih solid confidence interval.
>>Groups did not differ for postoperative complication rates. At 12 months, fewer graft occlusions, revisions, or critical stenoses were seen in the E2F-decoy group than in the untreated group (hazard ratio 0.34 [95% CI 0.12-0.99]). <<
My understanding is that meant there were 3x fewer fewer graft occlusions, revisions, or critical stenoses in the E2F-decoy group (if I'm misunderstanding this, Biokruncher or someone, please enlighten me!). I'll grant the point that the samples are small.
However, I've dug up results of another, larger, trial -- Prevent II:
medscape.com
Still looks good, though your concern about the fine line between failure or success is one I haven't been able to address entirely. Any lurking cardiologists want to take a swing at this? Supposedly, computers can analyze the image and come up with an accurate measurement, and were capable of doing so at the time of Prevent II:
cardiologysite.com
OTOH, there's this:
>>Circulation. 1995;91:2174-2183.)
Comparative Validation of Quantitative Coronary Angiography Systems
Results and Implications From a Multicenter Study Using a Standardized Approach
Presented in part at the 66th Scientific Sessions of the American Heart Association, Atlanta, Ga, November 8-11, 1993.
David Keane, MB, MRCPI; Jürgen Haase, MD, PhD; Cornelis J. Slager, PhD; Eline Montauban van Swijndregt, MSc; Kenneth G. Lehmann, MD; Yukio Ozaki, MD, PhD; Carlo di Mario, MD, PhD; Richard Kirkeeide, PhD; Patrick W. Serruys, MD, PhD
From the Cardiac Catheterization, Intracoronary Imaging, and Experimental Cardiology Laboratories, Thoraxcenter, Erasmus University, Rotterdam, the Netherlands, and the Division of Cardiology (R.K.), Health Science Center, University of Texas, Houston.
Correspondence to Prof P.W. Serruys, MD, PhD, FESC, Department of Interventional Cardiology, Thoraxcenter, Erasmus University, PO Box 1738, 3000 DR Rotterdam, Netherlands.
Background Computerized quantitative coronary angiography (QCA) has fundamentally altered our approach to the assessment of coronary interventional techniques and strategies aimed at the prevention of recurrence and progression of stenosis. It is essential, therefore, that the performance of QCA systems, upon which much of our scientific understanding has become integrally dependent, is evaluated in an objective and uniform manner.
Methods and Results We validated 10 QCA systems at core laboratories in North America and Europe. Cine films were made of phantom stenoses of known diameter (0.5 to 1.9 mm) under four experimental conditions: in vivo (coronary arteries of pigs) calibrated at the isocenter or by use of the catheter as a scaling device and in vitro with 50% contrast and 100% contrast. The cine films were analyzed by each automated QCA system without observer interaction. Accuracy and precision were taken as the mean and SD of the signed differences between the phantom stenoses, and the measured minimal luminal diameters and the correlation coefficient (r), the SEE, the y intercept, and the slope were derived by their linear regression. Performance of the 10 QCA systems ranged widely: accuracy, +0.07 to +0.31 mm; precision, ±0.14 to ±0.24 mm; correlation (r), .96 to .89; SEE, ±0.11 to ±0.16 mm; intercept, +0.08 to +0.31 mm; and slope, 0.86 to 0.64.
Conclusions There is a marked variability in performance between systems when assessed over the range of 0.5 to 1.9 mm. The range of accuracy, intercept, and slope values of this report indicates that absolute measurements of luminal diameter from different multicenter angiographic trials may not be directly comparable and additionally suggests that such absolute measurements may not be directly applicable to clinical practice using an on-line QCA system with a different edge detection algorithm. Power calculations and study design of angiographic trials should be adjusted for the precision of the QCA system used to avoid the risk of failing to detect small differences in patient populations. This study may guide the fine-tuning of algorithms incorporated within each system and facilitate the maintenance of high standards of QCA for scientific studies. <<
Things are better now? I have no idea . . .
There is a CGTK thread, we can move the discussion there if this is getting too OT for Peter or anyone.
Subject 54870
TIA & Cheers, Tuck |
