The Performance of the Revised Major Depression Inventory for Self-Reported Severity of Depression - Implications for the DSM-5 and ICD-11
Authors: Per Bech, Ellen Margrethe Christensen, Maj Vinberg, Søren Dinesen Østergaard, Klaus Martiny, Lars Vedel Kessing
Journal: Psychotherapy and Psychosomatics (2013)

Zimmerman's [1] editorial focuses on self-report instruments for the measurement of depressive severity in relation to DSM-5's dimensional approach to major depression. Zimmerman agrees with DSM-5's goal to adopt a dimensional measure of depression severity to be implemented in clinical practice. However, Zimmerman finds that the performance of one of the candidate scales, namely the Patient Health Questionnaire (PHQ-9) seems to be problematic. He especially refers to the study by Cameron et al. [2], which showed that, when compared to the Hamilton Depression Scale (HAM-D17), the PHQ-9 consistently placed the patient in a more severe category of depression. One reason for this might be that, in the HAM-D17, the two neurovegetative items (sleep and appetite) only cover insomnia and decreased appetite, while the PHQ-9 takes both hypo-/hypersomnia and hypo-/hyperappetite into account.The Major Depression Inventory (MDI) is a self-rating scale covering the symptom criteria of clinical depression for both DSM-IV and ICD-10 [3]. The scale has a double function as it can be used both as a diagnostic aid and as a measure of depression severity. When used dimensionally, the total score of the 10 items is a sufficient statistic for depression severity (unidimensionality). In the original MDI version [3] it was not possible to discriminate between hypo- and hypersomnia. However, in a newly revised version [4] we have included a specifier for the item concerning disturbed sleep by adding 'too little sleep' versus 'too much sleep' in order to assist the treating physician in identifying 'atypical' depression (too much sleep as well as increased appetite) [5].The objective of the present study was to investigate the degree of convergence between the categorical measure of depression severity as defined by the revised MDI and the HAM-D17. This is a clinimetric macroanalysis in accordance with Tomba and Bech [6].Patients were recruited from the Mood Disorder Clinic at the Psychiatric Centre Copenhagen. A total of 52 bipolar I patients and 57 patients with unipolar depression completed the revised MDI and were rated by trained HAM-D raters on HAM-D17. For further details, see Bech et al. [7].The conventional standardization of depression severity according to the MDI (0-20 = no clinical depression; 21-25 = mild depression; and 26 or more = moderate (major) depression) was compared to the NICE criteria (National Institute for Clinical Excellence in London) for mild and moderate depression on the HAM-D17 (0-13 = 'no depression', 14-18 = 'mild depression', and 19 or more = 'moderate/severe depression'), following the study by Cameron et al. [2]. Figure 1 shows the results of this comparison between MDI and HAM-D17 severity. The first group of columns shows the percentage convergence for all 109 patients. The tendency of the MDI to categorize patients in a more severe category than the HAM-D17 is statistically significant (p < 0.01). The second group of columns shows the percentage convergence for the 14 atypically depressed patients; here the above-mentioned tendency was even more pronounced. For the typically depressed patients (the third group of columns) the concordance between MDI and HAM-D17 was numerically more acceptable, but a tendency to place patients in a more severe category than HAM-D17 was still found.Dimensional rating scales can be used to quantify the severity and improvement/worsening of mental states and are therefore invaluable tools in both clinical practice and research. When evaluating self-rating scales for major depression, it is essential to use item response theory models to ensure that the total score of the scales are meaningful measures of severity [4]. So far, no direct comparison between the MDI and the PHQ-9 has been performed. We have recently compared the MDI with the Beck Depression Inventory (BDI) [8] using the nonparametric item response model [4]. We obtained a coefficient of homogeneity of 0.60 for the MDI, but only 0.27 for the BDI [9]. A coefficient of homogeneity of 0.40 or higher indicates unidimensionality [4].In the present study, the MDI displayed a tendency to place patients in a more severe depression category than did the HAM-D17. The HAM-D17 uses a time frame (window) of 1 week. In a previous study [10], covering a trial with treatment-resistant typical DSM-IV major depression, we modified the MDI time frame from 2 weeks to the past week. When reanalyzing all observations from this study, the total MDI score had an acceptable convergence with HAM-D17 using the NICE standardization. Consequently, the time frame (2 weeks vs. 1 week) might explain the difference between MDI and HAM-D17 severity scores found in the current study.Excluding patients with atypical depression only increased the percentage convergence between MDI and HAM-D17 modestly, probably due to the rather small number of patients with atypical depression (13%). In our DUAG (Danish University Antidepressant Group) study comparing moclobemide with clomipramine, 11% in the total population of depressed patients were identified with atypical depression defined by increased sleep or increased appetite [5]. However, we were able to show that moclobemide was superior to clomipramine in this small subgroup of patients with atypical depression [5].PHQ-9 is a trademark of Pfizer Inc. as emphasized by Zimmerman, and the BDI requires payment per use. In contrast, the MDI is totally independent from corporate and financial interests.In conclusion, the revised version of the MDI is a unidimensional self-rating scale for the measurement of depression severity and can be of help in identifying patients with atypical depression. Compared to the PHQ-9 and the BDI, the advantage of MDI is its unidimensionality, the ability to distinguish between atypical and typical depression, and the lack of financial and corporate interests. We suggest that the updated MDI should be considered as the depression self-rating scale of choice in the DSM-5 and ICD-11.The study was supported by the Hovedstadens Sygehusfællesskab (The Capital Hospital Corporation). The sponsor had no role in the study design; in the collection, analysis and interpretation of data; in the writing of the report; or in the decision to submit the paper for publication. P. Bech has no conflicts of interests. E.M. Christensen has been a consultant for Bristol-Myers Squibb, Astra-Zeneca, Eli Lilly, MSD, and Servier. M. Vinberg has been a consultant for Astra-Zeneca, Lundbeck, Servier, and Eli Lilly. S.D. Østergaard has received speaking fees and consultant honoraria from Janssen-Cilag until April 2011. K. Martiny has occasionally served as a speaker for pharmaceutical companies with an interest in the drug treatment of affective disorders (Lundbeck, Servier, and Eli Lilly). L.V. Kessing has been a consultant for Bristol-Myers Squibb, Eli Lilly, Lundbeck, Astra-Zeneca, Pfizer, Wyeth, and Servier.