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To the Editor.—
Dictionary synonyms of the word "outcome" include "result," "consequence," and "effect." All imply the existence of a causal relationship. It would appear gratuitous of Luborsky et al in "Predicting the Outcome of Psychotherapy: Findings of the Penn Psychotherapy Project" (Archives 1980;37:471-481) to assume that all of the changes in their patients' conditions were caused by psychotherapy. What about the natural course of illness and other life events? One might also wonder whether some of the unchanged conditions would have become worse without psychotherapy.The multivariate prediction of which patients will respond to psychotherapy is only meaningful when the predictors are adjusted to reflect those observed in an untreated control group. Otherwise one has studied prognosis and not treatment. This is not to gainsay the logistical and ethical complexities of research on psychotherapy. But it is disappointing, if not disquieting, to find leading authorities on the subject completely