NEO-FFI factor scores as predictors of clinical response to fluoxetine in depressed outpatients

Research in unipolar depression suggests that neuroticism is associated with poor long-term outcome and greater chronicity. The objective of this study was to determine whether baseline neuroticism scores predict response to treatment with fluoxetine in depressed outpatients. Seventy-six depressed outpatients participating in a clinical trial of fluoxetine (fixed/flexible dosing) completed the NEO-FFI (five factor inventory short form) at baseline. Clinical response was defined as a 50% or greater decrease in the 17-item Hamilton Depression Rating Scale (HAM-D-17) total score (final visit - baseline). Logistic regression evaluated NEO-FFI factor scores as predictors of treatment outcome within an intent-to-treat model. Scores on the neuroticism scale were not found to significantly predict treatment response as measured by the HAM-D-17. Strengths of this study include a standardized treatment protocol and use of structured interview instruments, while limitations include a modest sample size, lack of continuation data, state/trait effects, and lack of generalizability to other antidepressant treatments.