Predictors of remission with placebo using an integrated study database from patients with major depressive disorder.

OBJECTIVE: To identify predictors of remission with placebo treatment in double-blind randomized controlled trials (RCTs) in major depressive disorder (MDD). METHOD: A total of 1017 placebo-treated patients with baseline Hamilton Depression rating scale (HAMD) total ≥15 from eight duloxetine RCTs were included. Remission was defined as endpoint (7-8 weeks) HAMD total ≤7. Data were randomly split into training data (N = 813, 80%) for model selection and test data (N = 204, 20%) for validation. Logistic regression and classification and regression tree (CART) methods were used to identify predictors of remission. Predictive accuracy of models was assessed by Receiver Operator Characteristic (ROC) curves. RESULTS: Baseline predictors for remission with placebo consistently identified with the logistic regression and CART analysis were less severe depressive symptoms (based on HAMD core symptoms), younger age, less anxiety (based on HAMD anxiety/somatization), and shorter current MDD episode duration. Associated cut-off values from the CART method characterized patient groups according to their remission likelihood. However, the predictive accuracy was modest for both methods with areas under the ROC curve of 0.6-0.65 based on test data. CONCLUSION: The derived models, although of limited value for predicting remission in individual patients, may be useful for adjusting for placebo effects in clinical trials.

In search of optimal lithium levels and olanzapine doses in the long-term treatment of bipolar I disorder. A post-hoc analysis of the maintenance study by Tohen et al. 2005.

PURPOSE: The aim of this study was to investigate whether lower lithium levels (LoLi) or olanzapine doses (LoOL) are risk factors for future mood episodes in patients with bipolar I disorder. METHODS: A post-hoc analysis of the olanzapine-lithium-maintenance study [31] was performed using proportional hazards Cox regression models and marginal structural models (MSMs), adjusting for non-random assignments of dose during treatment. RESULTS: The LoLi group (<0.6 mmol/L) had a significantly increased risk of manic/mixed (hazard ratio [HR]=1.96, p=0.042), but not depressive (HR=2.11, p=0.272) episodes, compared to the combined medium (0.6-0.79 mmol/L) and high lithium level (≥0.8 mmol/L) groups. There was no significant difference in risk between the two higher lithium level groups (0.6-0.79 mmol/L; ≥0.8 mmol/L) for new manic/mixed (HR=0.96, p=0.893) or depressive (HR=0.95, p=0.922) episodes. The LoOL group (<10mg/day) showed a significantly increased risk of depressive (HR=2.24, p=0.025) episodes compared to the higher olanzapine (HiOL) dose group (HiOL: 10-20 mg/day), while there was no statistically significant difference in risk for manic/mixed episodes between the two groups (HR=0.94, p=0.895). CONCLUSION: Lithium levels≥0.6 mmol/L and olanzapine doses≥10mg/day may be necessary for optimal protection against manic/mixed or depressive episodes, respectively in patients with bipolar I disorder.