Efficient allocation of patients to treatment cells in clinical trials with more than two treatment conditions.
OBJECTIVE
Clinical trials generally allocate patients to equal-sized treatment groups. The authors propose that it may be more efficient to allocate unequal proportions of the total sample size to treatments when more than two treatments are being compared.


METHODS
This proposal is illustrated with two examples. One involved a comparison of three treatments and used a dichotomous categorical outcome. The other involved comparison of three treatments and used a continuous measure.


RESULTS
In both examples, a considerable increase in efficiency was realized by reducing the number of patients assigned to the placebo cell.


CONCLUSIONS
Unequal allocation of patients to treatments should be considered when more than two groups are compared.
Connecticut Mental Health Center, Yale University School of Medicine Department of Psychiatry, New Haven 06508, USA. scott.woods@yale.edu
S W
SW
Woods
D E
DE
Sholomskas
M K
MK
Shear
J M
JM
Gorman
D H
DH
Barlow
A W
AW
Goddard
J
J
Cohen
D000928:Antidepressive Agents / Q000627:therapeutic use; D014150:Antipsychotic Agents / Q000627:therapeutic use; D002985:Clinical Protocols; D002986:Clinical Trials as Topic / Q000379:methods* / Q000592:standards; D006801:Humans; D018579:Patient Selection; D010919:Placebos; D012107:Research Design; D016896:Treatment Outcome
D000928:Antidepressive Agents; D014150:Antipsychotic Agents; D010919:Placebos