Cumulative morbidity and prognostic staging of illness in the Systematic Treatment Enhancement Program for Bipolar Disorder (STEP-BD)

Abstract

Objective: Staging models may provide heuristic utility for intervention selection in psychiatry. Although a few proposals have been put forth, there is a need for empirical validation if they are to be adopted. Using data from the Systematic Treatment Enhancement Program for Bipolar Disorder (STEP-BD), we tested a previously elaborated hypothesis on the utility of using the number of previous episodes as a relevant prognostic variable for staging in bipolar disorder. Methods: This report utilizes data from the multisite, prospective, open-label study ‘Standard Care Pathways’ and the subset of patients with acute depressive episodes who participated in the randomized trial of adjunctive antidepressant treatment. Outpatients meeting DSM-IV diagnostic criteria for bipolar disorder ( n = 3345) were included. For the randomized pathway, patients met criteria for an acute depressive episode ( n = 376). The number of previous episodes was categorized as less than 5, 5–10 and more than 10. We used disability at baseline, number of days well in the first year and longitudinal scores of depressive and manic symptoms, quality of life and functioning as validators of models constructed a priori. Results: Patients with multiple previous episodes had consistently poorer cross-sectional and prospective outcomes. Functioning and quality of life were worse, disability more common, and symptoms more chronic and severe. There was no significant effect for staging with regard to antidepressant response in the randomized trial. Conclusions: These findings confirm that bipolar disorder can be staged with prognostic validity. Stages can be used to stratify subjects in clinical trials and develop specific treatments.