Major Depression Index (MDI)

MDI explained

The major depression index addresses the most common symptoms associated with depressive disorder and is used in practice in two different ways:

■ As initial screening tool;

■ To check progress of already diagnosed patients between subsequent evaluations.

The MDI is a self-report questionnaire containing 12 questions in total. These relate to 4 groups of day to day activities, feelings and reactions that are characteristic to depressive disorder.

The instruction to be given to the patient, before the questionnaire is administered, is to refer to their experiences from the past 2 weeks:

The first three items refer to mood changes, loss of interest and energy levels:

1. Low in spirits or sad;

2. Lost interest in your daily activities;

3. Lacking in energy and strength;

Items 4 and 5 refer to feelings of self-confidence and guilty, whilst items 6 and 7 refer to concentration capacity and feelings of motivation. Item 6 is the only item in the index that is aimed at revealing the existence or not of suicidal ideation, one of the major depression symptoms.

4. Less self-confident;

5. Bad conscience or feelings of guilt;

6. Feeling that life wasn’t worth living;

7. Difficulty in concentrating;

Items 8a and 8b refer to psychomotor changes, item 9 addresses sleep issues whilst items 10a and 10b refer to eating habits.

8a. Feeling very restless;

8b. Feeling subdued or slowed down;

9. Trouble sleeping at night;

10a. Reduced appetite;

10b. Increased appetite;

The assessment method is very simple, each of the questions being presented with the same 6 answer choices, on an increasing scale of symptom frequency:

■ At no time (0 points);

■ Some of the time (1 point);

■ Slightly less than half of the time (2 points);

■ Slightly more than half of the time (3 points);

■ Most of the time (4 points);

■ All the time (5 points).

Each question is then given a numerical score and these are added in the end to determine the final score.

Result interpretation

As a screening system, the MDI checks for the existence and severity of depression based on the symptoms the subject experiences and on their frequency.

The final score range between 0 and 50, where 0 indicates no depression and 50 indicates severe depression.

There are three cut off points at scores of 20, 25 and 30, that create four categories of screening outcomes:

The original study also provides an alternative interpretation of the questionnaire (that takes into account DSM-IV and ICD-10 definitions of moderate to severe depression) based on symptom frequency. A score of 4 or 5 points in at least:

■ 2 of the first 3 items + 2 of the first 7 items, is consistent with mild depression ICD-10;

■ 2 of the first 3 items + 4 of the first 7 items, is consistent with moderate depression ICD-10;

■ all of the first 3 items + 5 of the first 7 items, is consistent with severe depression ICD-10;

■ 1 of the first 2 items + 5 of all 9 items, is consistent with major depression DSM-IV.

About the study

The MDI was constructed following a study by Bech et al. in 2001, as an inventory of patient self-reported depression symptoms.

The sensitivity and specificity of the MDI were assessed in a cohort of 43 patients suffering from a wide range of depressive symptoms. Patients with psychotic depression were not included.

The sensitivity of the tool was found to be between 0.86 and 0.92, whilst the specificity varied between 0.82 and 0.86. An optimal cut-off score was estimated at 26.

Other depression screening tools

The following tools help screen or evaluate the severity of depressive symptoms in adult and geriatric patients:

■ The Zung self-rating depression scale determines depression severity and benefits from two different scoring systems for increased accuracy.

■ The Geriatric depression scale (GDS) test – is the most used evaluation tool for elderly patients suspected or already diagnosed with depression. This benefits from a standard 15-question version and a short, 4-question version.

Original source

Bech P, Rasmussen NA, Olsen LR, Noerholm V, Abildgaard W. The sensitivity and specificity of the Major Depression Inventory, using the Present State Examination as the index of diagnostic validity. J Affect Disord. 2001; 66(2-3):159-64.

Validation

Olsen LR, Jensen DV, Noerholm V, Martiny K, Bech P. The internal and external validity of the Major Depression Inventory in measuring severity of depressive states. Psychol Med. 2003; 33(2):351-6.