The recovery index: A novel approach to measuring recovery and predicting remission in major depressive disorder.

BACKGROUND: Clinicians view "recovery" as the reduction in severity of symptoms over time, whereas patients view it as the restoration of premorbid functioning level and quality of life (QOL). The main purpose of this study is to incorporate patient-reported measures of functioning and QOL into the assessment of patient outcomes in MDD and to use this data to define recovery.

METHOD: Using the STAR*D study of patients diagnosed with MDD, this present analysis grades patients' MDD severity, functioning level, and QOL at exit from each level of the study, as well as at follow-up. Using Item Response Theory, we combined patient data from functioning and QOL measures (WSAS, Q-LES-Q) in order to form a single latent dimension named the Recovery Index.

RESULTS: Recovery Index - a latent measure assessing impact of illness on functioning and QOL - is able to predict remission of MDD in patients who participated in the STAR*D study.

CONCLUSIONS: By incorporating functioning and quality of life, the Recovery index creates a new dimension towards measuring restoration of health, in order to move beyond basic symptom measurement.