Discriminant function analysis of data from a double-blind comparative trial of lofepramine
(a noradrenaline-specific reuptake inhibitor) and fluoxetine (a serotonin-specific
reuptake inhibitor), involving 183 patients was used to identify predictors of response.
Psychic anxiety significantly predicted a positive response to antidepressant medication,
whereas psychomotor retardation, observed sadness, subjective lassitude and somatic
complaints were significant predictors of nonresponse. Age, gender, endogenicity,
duration of illness and number of previous episodes were not predictive of response.
Significant differences were found between predictors of response to fluoxetine and
lofepramine (P < 0.001 all groups). Predictors of response to lofepramine were similar
to overall predictors, i.e., psychic anxiety predicted responders whilst observed
sadness, psychomotor retardation, lassitude, inability to feel and somatic complaints
predicted nonresponders. In contrast, baseline weight loss predicted response to fluoxetine,
whereas anxiety, reduced insight and a tendency to blame others significantly predicted
nonresponse. Such findings have practical implications for the management of depressive
illness.