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Survival analysis techniques in angina pectoris trials
Abstracts
291
Order-Restricted Inference Methods with Application to Dose-Response Designs Michael J. Schell
St. Jude's Children's Hospital, Memphis, Tennessee (35) Order restricted inference methodology is useful in clinical trials which test for a dose-response treatment effect. These methods assume an a priori partial ordering on the means (V,,,i= 1..... k) of k treatment groups. Three partial orders of particular interest are the simple order (v-i<~v-2~
Survival Analysis Techniques in Angina Pectoris Trials David R. Bristol a n d J o h n V. C a s t e l l a n a
Development Dept., CIBA-GEIGY Corp., Summit, New Jersey (36) The variable "total walking time" on an exercise stress test is the primary means for judging new treatments of angina pectoris. This variable is the time to angina or fatigue. Statistical analyses are usually performed on this variable using procedures that require the assumption of an underlying normal distribution. However, time to angina is the variable of interest and time to fatigue is not treatment-dependent. Thus, fatigue is a censoring variable and it is proposed that survival analysis techniques be employed in such trials. An example from a recent placebocontrolled multicenter clinical trial is presented. The results from some simulations are also presented to compare the results of various analyses. Evaluating Serial Coronary Arteriograms: Progress Report on the POSCH AI Project J.M. Long, J.R. Slagle, E. Irani, D.W. H u n t e r , M. S a n m a r c o , a n d t h e POSCH Group University of Minnesota, Minneapolis, Minnesota (37) POSCH is attempting to use more automation in its data analysis. Earlier reports discussed a plan to automate the discovery process 0985) and described a system that can evaluate pairs of exercise ECG tests (1986). This third report describes our efforts at building an expert system that can evaluate the data from a pair of coronary arteriograms and approximate the conclusions of a panel in their final step of evaluation when they make a global assessment of change over time using the following scale--much better, better, slightly better, no change, slightly worse, worse, much worse. POSCH quality surveillance data indicate that two different panels will select the same category 55% of the time and the same or adjacent category 91% of the time. The expert system can approximate a panel's global assessment by selecting the same category 50% of the time and the same or immediately adjacent categories 96% of the time. The surprising results indicate that it may be possible for an expert system to compensate for some of the information that is visually acquired by a human subject.
The Design of a Randomized, Multicenter Study of Sodium Dichloroacetate (DCA) as a Treatment for Lactic Acidosis The D C A - L a c t i c A c i d o s i s C o l l a b o r a t i v e S t u d y G r o u p
The Biostatistics Center, The George Washington University, Rockville, Maryland
(38) Lactic acidosis occurs in about 1% of adult hospital admissions and has a mortality between 60% and 95%, depending on etiology. DCA has been shown to decrease lactate levels, but its effect on survival is unknown. The DCA-Lactic Acidosis Collaborative Study is a multicenter, randomized, double-blind placebo controlled study designed to evaluate DCA as a treatment for ICU patients with lactic acidosis. The primary outcomes are all-cause mortality, length of ICU and hospital stay, response to treatment (defined as a 20% fall in lactate level within 6 hours of therapy), and the requirement for sodium bicarbonate. The study organization includes eight
291
Order-Restricted Inference Methods with Application to Dose-Response Designs Michael J. Schell
St. Jude's Children's Hospital, Memphis, Tennessee (35) Order restricted inference methodology is useful in clinical trials which test for a dose-response treatment effect. These methods assume an a priori partial ordering on the means (V,,,i= 1..... k) of k treatment groups. Three partial orders of particular interest are the simple order (v-i<~v-2~
Survival Analysis Techniques in Angina Pectoris Trials David R. Bristol a n d J o h n V. C a s t e l l a n a
Development Dept., CIBA-GEIGY Corp., Summit, New Jersey (36) The variable "total walking time" on an exercise stress test is the primary means for judging new treatments of angina pectoris. This variable is the time to angina or fatigue. Statistical analyses are usually performed on this variable using procedures that require the assumption of an underlying normal distribution. However, time to angina is the variable of interest and time to fatigue is not treatment-dependent. Thus, fatigue is a censoring variable and it is proposed that survival analysis techniques be employed in such trials. An example from a recent placebocontrolled multicenter clinical trial is presented. The results from some simulations are also presented to compare the results of various analyses. Evaluating Serial Coronary Arteriograms: Progress Report on the POSCH AI Project J.M. Long, J.R. Slagle, E. Irani, D.W. H u n t e r , M. S a n m a r c o , a n d t h e POSCH Group University of Minnesota, Minneapolis, Minnesota (37) POSCH is attempting to use more automation in its data analysis. Earlier reports discussed a plan to automate the discovery process 0985) and described a system that can evaluate pairs of exercise ECG tests (1986). This third report describes our efforts at building an expert system that can evaluate the data from a pair of coronary arteriograms and approximate the conclusions of a panel in their final step of evaluation when they make a global assessment of change over time using the following scale--much better, better, slightly better, no change, slightly worse, worse, much worse. POSCH quality surveillance data indicate that two different panels will select the same category 55% of the time and the same or adjacent category 91% of the time. The expert system can approximate a panel's global assessment by selecting the same category 50% of the time and the same or immediately adjacent categories 96% of the time. The surprising results indicate that it may be possible for an expert system to compensate for some of the information that is visually acquired by a human subject.
The Design of a Randomized, Multicenter Study of Sodium Dichloroacetate (DCA) as a Treatment for Lactic Acidosis The D C A - L a c t i c A c i d o s i s C o l l a b o r a t i v e S t u d y G r o u p
The Biostatistics Center, The George Washington University, Rockville, Maryland
(38) Lactic acidosis occurs in about 1% of adult hospital admissions and has a mortality between 60% and 95%, depending on etiology. DCA has been shown to decrease lactate levels, but its effect on survival is unknown. The DCA-Lactic Acidosis Collaborative Study is a multicenter, randomized, double-blind placebo controlled study designed to evaluate DCA as a treatment for ICU patients with lactic acidosis. The primary outcomes are all-cause mortality, length of ICU and hospital stay, response to treatment (defined as a 20% fall in lactate level within 6 hours of therapy), and the requirement for sodium bicarbonate. The study organization includes eight