Inter-relationship of the functional status question of the PHQ-9 and depression remission after six months of collaborative care management

In collaborative care management (CCM) for depression, a restoration of premorbid functional status is as important as symptom reduction. The goal of this study was to investigate if the baseline functional status of the patient (as determined by the tenth question of the PHQ-9) was an independent predictor of clinical outcomes six months after enrollment into CCM and the interdependence of clinical outcomes on functional improvement at six months. One thousand eighty three adult patients who were enrolled in CCM for the diagnosis of major depression or dysthymia and had a PHQ-9 score of 10 or greater were retrospectively reviewed. Using a multiple regression model for clinical remission six months after enrollment into CCM; age, race and gender were not significant predictors of remission, however, being married was (OR 1.323 CI 1.013-1.727, P = 0.040). Patients in the Extremely Difficult category had an odds ratio of remission of 0.610 (CI 0.392-0.945, P = 0.028) at six months compared to the Somewhat Difficult group. Also, the odds of a patient achieving normal functional status at six months was highly correlated to clinical remission (PHQ-9 <5) with an odds ratio of 218.530 (P < 0.001).Depressed patients with worsening functional status at enrollment into CCM are less likely to achieve remission after six months, independent of all other variables studied. Also, improvement of a patient's functional status at six months was highly correlated with clinical remission.