Psychological health-sickness (PHS) as a predictor of outcomes in dynamic and other psychotherapies.

This is the first dedicated review of quantitative studies on Sigmund Freud's proposition that the poorer the psychological health, the more limited are the benefits from treatment. Since observer-rated scales for psychological health-sickness were developed in 1949, many studies have applied them, and the majority show significant prediction of outcomes of psychotherapy, with correlations between .2 and .35. This article reviews (a) the main methods of measurement, (b) the record of predictive success, (c) validity studies, (d) the relation to psychiatric diagnosis, (e) prediction in forms of treatment other than psychotherapy, and (e) theories of why psychological health predicts outcomes of psychotherapy.