Patient-reported depression severity and cognitive symptoms as determinants of functioning in patients with major depressive disorder: a secondary analysis of the 2-year prospective PERFORM study

PURPOSE: To investigate the temporal interrelationship between depression severity, cognitive symptoms, and functioning in patients with major depressive disorder (MDD) in the PERFORM study (NCT01427439). PATIENTS AND METHODS: PERFORM was a 2-year, multicenter, prospective, noninterventional cohort study in outpatients with MDD who were either initiating antidepressant monotherapy or undergoing their first switch of antidepressant. Patients were enrolled by a general practitioner or psychiatrist. Structural equation model (SEM) analysis was used to explore temporal associations between patient-reported depression severity (9-item Patient Health Questionnaire score), cognitive symptoms (5-item Perceived Deficits Questionnaire score), and functional impairment (Sheehan Disability Scale total score). Standardized regression coefficients (SRCs) were used to evaluate the relationship between each outcome and scores from the most recent prior visit over the 2 years of follow-up. RESULTS: Between February 25, 2011, and February 19, 2015, 1,159 eligible patients with MDD completed the baseline and ≥1 follow-up visit at 194 sites in five European countries (France, Germany, Spain, Sweden, and the UK). Overall, 1,090 patients had assessments for ≥1 outcome measure at two consecutive visits. Severity of cognitive symptoms at baseline and Months 2 and 18 predicted functional impairment at Months 2, 6, and 24, respectively (SRC: 0.18, 0.15, and 0.22; P<0.001). Depression severity at Months 2, 6, and 12 predicted functional impairment at Months 6, 12, and 18, respectively (SRC: 0.17, 0.25, and 0.22; P<0.001). Severity of cognitive symptoms at baseline and Month 18 predicted depression severity at Months 2 and 24, respectively (SRC: 0.19 and 0.22; P<0.001). Functional impairment did not significantly predict the severity of depression or cognitive symptoms, and depression severity did not significantly predict the severity of cognitive symptoms at any time point. CONCLUSION: Patient-reported severity of cognitive symptoms appears to be an independent and significant determinant of subsequent functional impairment and depression severity in patients with MDD.