Baseline Difference Between Patients’ and Clinicians’ Rated Illness Severity Scores and Subsequent Outcomes in Major Depressive Disorder: Analysis of the Sequenced Treatment Alternatives to Relieve Depression Data

Major Depressive Disorder (MDD) is a major public health concern in that it is associated with increased functional disability and mortality1, 2 as well as a great deal of economic loss.3, 4 MDD is characterized by a variety of symptoms, including depressive mood, diminished interest or pleasure, feelings of worthlessness, and psychomotor agitation; therefore, it is sometimes difficult to thoroughly evaluate their symptoms. Since the appropriate evaluation of symptoms is prerequisite for effective treatment of this illness, recent guidelines recommend the use of systematic rating scales for measurement-based treatment even in daily clinical practice.5-7 There are mainly two types of assessment scales of symptomatology in MDD: clinician-rated and self-rated.8 Although concordance between clinician-rated and self-rated illness severity has been reported to be generally moderate, it is not always perfect.9-12 For example, the presence of personality traits such as low self-esteem and co-morbid borderline personality disorder has been reported to be associated with more severe subjective psychopathology than objectively evaluated by a clinician.13, 14 Moreover, younger age, higher educational background, and female sex are reportedly predictive of higher scores in the self-rated scales relative to the clinician-rated ones.10, 15 Such a gap between clinician-rated and self-rated severity of MDD is not only attributable to flaws in those assessment scales, but to this illness itself, to some extent. For example, this difference could have an impact on the treatment outcomes; patients who regard the illness as more severe than objectively assessed may be more pessimistic about antidepressant treatment, which in turn could result in unfavorable treatment outcomes. To our knowledge, only two studies have tried to address this important issue.16, 17 Rane et al. found that a greater difference between scores in the Beck Depression Inventory (BDI) and the 21-item version of the Hamilton Depression Rating Scale (HDRS21) predicted a slower response to regular routine treatment with pharmacotherapy, psychotherapy, and/or electroconvulsive therapy, independent of objective illness severity, in 103 patients with treatment-resistant depression. On the other hand, they failed to find any significant difference in the difference scores between the subjects who responded and those who did not.16 Dunlop et al. conducted an analysis of data from the Prevention of Recurrent Episodes of Depression With Venlafaxine Extended Release for Two Years (PREVENT) trial, in which participants were divided into the following three groups according to discrepancies between the Inventory of Depressive Symptoms-Self Report score and the 17-item version of the Hamilton Depression Rating Scale (HDRS17) score: concordant patients (n=714), underrating patients (n=164), and overrating patients (n=148). While overrating patients at baseline fulfilled the clinician-rated response criteria more slowly than the others, no significant differences were observed in remission or response rates between the groups.17 However, it is somewhat difficult to extrapolate these findings to a general population with MDD since they solely focused on treatment-resistant or recurrent depression. More critically, the previous studies did not use the same scales for subjective and objective assessments. To address the gap in the literature, in the present study, we examined the association of the difference between subjective and objective severity of the illness with the subsequent response to antidepressant treatment in a greater number of patients with MDD, using the data from the Sequenced Treatment Alternatives to Relieve Depression (STAR*D) study. In this trial, patients were assessed with both clinician-rated and self-rated scales that include exactly the same items: the 16-item Quick Inventory of Depressive Symptomatology, Clinician Rating (QIDS-C16)18 and the 16-item Quick Inventory of Depressive Symptomatology, Self-Report (QIDS-SR16). 18