Predictors of response to lithium augmentation in tricyclic antidepressant-resistant depression

Background: The efficacy of lithium augmentation in therapy-resistant depression has been shown in a series of well-designed, placebo-controlled studies. However, little is known about the predictors of a good response to this treatment strategy. Methods: We retrospectively examined the predictive value of 20 demographic, clinical, biochemical and endocrinological variables using a two-step logistic regression. Seventy-one in-patients with depression refractory to tricyclic antidepressants had received lithium augmentation as part of a standardised treatment protocol. Results: Within 4 weeks 37 patients (52%) responded to lithium augmentation. Five variables with predictive value were found. Responders were more severely depressed according to Bech-Rafaelsen Melancholia Scale. The duration of their index episode was shorter. Triiodothyronine serum levels were lower and neuroleptic co-medication and co-diagnosis of personality disorder were less frequent. Limitations: This was an open, retrospective study. Conclusions: Severity of depression is a predictor of response to lithium augmentation. This result conflicts with recent studies but is similar to results found in studies of other a pharmacological antidepressant strategies. (C) 2001 Elsevier Science B.V. All rights reserved.