Major Depression Inventory MDI
Major Depression Inventory MDI overview
Creator and Context
The Major Depression Inventory (MDI) is a self report measure that does something unusual: it produces both a depression severity score and an ICD-10 or DSM diagnostic classification from the same responses.
It was developed by a team led by Professor Per Bech at the WHO Collaborating Centre for Mental Health in Denmark, with the key validation published in 2001.
Presenting Conditions
The MDI covers the ICD-10 core and additional symptoms of depression: low mood, loss of interest, reduced energy, reduced confidence, guilt, thoughts of self harm, concentration difficulty, agitation or retardation, sleep disturbance and appetite change.
It is unidimensional and has no subscales, but the same items feed a separate diagnostic algorithm.
Administration
Self administered, covering the past two weeks. Each item is rated on a 6 point frequency scale from At no time (0) to All of the time (5).
There are 12 printed items but only 10 scored items. Items 8 and 10 each have two sub items, and only the higher of each pair counts.
Desired Audience
Adults. It is used in primary care, specialist mental health and research settings.
The MDI is the rare instrument that gives you both a severity score for tracking and a symptom algorithm mapped to ICD-10 criteria. For services reporting against ICD-10 rather than DSM, that alignment saves a translation step.
Considerations
The 12 printed items versus 10 scored items distinction is the most common implementation error. Items 8 and 10 use the higher of their two sub items.
The severity score and the diagnostic algorithm are two different scoring paths on the same responses, and they can disagree. A total score alone does not yield a diagnosis.
A one week version exists alongside the standard two week version. Be explicit about which is in use.
Diagnostic performance has been reported as lower in outpatient samples than in the original validation.
It is free of charge for clinicians and researchers, but a licence for commercial redistribution should be confirmed.
How to score the Major Depression Inventory MDI
Conducting the assessment
The person rates each item on the 0 to 5 frequency scale for the past two weeks. Items 8 and 10 each contain two sub items, and only the higher of each pair is scored.
Interpretation
The ten scored items are summed to give a total from 0 to 50.
Severity bands, confirmed against clinician ratings in the 2015 LEAD validation:
0 to 20 no or doubtful depression
21 to 25 mild depression
26 to 30 moderate depression
31 to 50 severe depression
The same responses can also be run through an ICD-10 symptom algorithm, which requires specified combinations of core and additional symptoms at defined intensities. The algorithm and the severity score are separate outputs.
Clinical Considerations
Do not present the total score as a diagnosis. Where you need a classification, run the algorithm.
Verify the sub item logic in any digital implementation.
Watch the self harm item independently of the total.
Major Depression Inventory MDI use cases
Measuring depression severity in adults
Producing an ICD-10 aligned symptom classification
Monitoring change across treatment
Research and epidemiology
Category
Depression
Research Summary
Bech, P., Rasmussen, N. A., Olsen, L. R., Noerholm, V., & Abildgaard, W. (2001). The sensitivity and specificity of the Major Depression Inventory, using the Present State Examination as the index of diagnostic validity. Journal of Affective Disorders, 66(2-3), 159 to 164.
Olsen, L. R., Jensen, D. V., Noerholm, V., Martiny, K., & Bech, P. (2003). The internal and external validity of the Major Depression Inventory in measuring severity of depressive states. Psychological Medicine, 33(2), 351 to 356.
Bech, P., Timmerby, N., Martiny, K., Lunde, M., & Soendergaard, S. (2015). Psychometric evaluation of the Major Depression Inventory (MDI) as depression severity scale using the LEAD as index of validity. BMC Psychiatry, 15, 190.
Other Assessment Guides
Beck Depression Inventory BDI
Explore the Beck Depression Inventory (BDI): a detailed guide covering its use, administration, scoring, and interpretation for assessing depression severity in clinical and research settings.
Edinburgh Postnatal Depression Scale EPDS
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Patient Health Questionnaire PHQ-9
Uncover the essentials of the Patient Health Questionnaire (PHQ-9), a prominent tool for depression screening and severity assessment. Our comprehensive guide details its administration, scoring, and clinical application, ideal for healthcare practitioners and mental health researchers.
Note on Assessment licensing
Some assessments are copyright protected and require a licence or the copyright holder's permission for clinical, commercial or digital use. Where that applies, obtaining and maintaining that permission is the responsibility of the practice or organisation using the assessment. Tacklit provides the digital administration, scoring and reporting. We do not grant, transfer or supply rights to the underlying instrument.
