Summary measures were a useful alternative for analyzing therapeutic clinical trial data.
OBJECTIVE
To compare use of both a pooled index and area under the curve (AUC) to the standard analysis of a randomized controlled trial of antibiotics for patients with Alzheimer's disease.


METHODS
Using data from a randomized, placebo-controlled trial of antibiotics for patients with Alzheimer's disease, a pooled index of six outcome measures was constructed. Each change score was standardized by dividing by the standard deviation, and the six standardized change scores were averaged. The Standardized Alzheimer's Disease Assessment Scale cognitive subscale and the pooled index were plotted against time and the AUC was calculated.


RESULTS
The AUC analysis of the pooled index showed significant treatment effect over the 12-month period. In contrast, none of the individual measures showed an effect at more than one time point. The AUC analyses of the Standardized Alzheimer's Disease Assessment Scale cognitive subscale, the primary outcome of the trial, showed no significant difference over the entire 12-month period, although the original individual time-point analysis showed a difference at 6 months alone.


CONCLUSIONS
Pooled indices and AUC analyses may provide important insight into therapeutic effect of agents tested in randomized clinical trials of patients with Alzheimer's disease.
Department of Clinical Epidemiology and Biostatistics, McMaster University, 1200 Main Street W., Hamilton, Ontario L8N 3Z5, Canada.
Soo Chan
SC
Carusone
Charlie H
CH
Goldsmith
Marek
M
Smieja
Mark
M
Loeb
D000203:Activities of Daily Living; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000188:drug therapy*; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D019540:Area Under Curve; D003627:Data Interpretation, Statistical; D004318:Doxycycline / Q000627:therapeutic use; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011569:Psychiatric Status Rating Scales; D011594:Psychometrics; D012293:Rifampin / Q000627:therapeutic use; D016896:Treatment Outcome
D000900:Anti-Bacterial Agents; D004318:Doxycycline; D012293:Rifampin