Simplification of the Beck Depression Inventory

The Beck Depression Inventory (BDI; Beck, 1978; Beck & Steer, 1987) is one of the most widely used instruments for measuring depression. It has been translated into many languages and has been used both in basic research and for assessing depression in various clinical settings. Numerous studies attest that the BDI demonstrates high reliability and construct validity (Beck, Steer, & Garbin, 1988). One drawback of the original version of the inventory (BDI-O) is its item format. The BDI-O includes 21 symptoms of depression. Each symptom is described via four statements with increasing difficulty. Participants are asked to indicate which of the four statements describes their thoughts, feelings, and behaviors best. Values of 0, 1, 2, and 3 are assigned to the statements with larger values indicating more severe kinds of depressive thoughts, feelings, and behaviors. The total BDI-O score is obtained by summing across the 21 symptom-scores. As a consequence of this format, participants have to read a total of 84 items. Reading 84 statements sometimes exceeds the capacity of acutely depressive people. Its length also makes the BDI-O inefficient for studies that include a large number of constructs and a large number of participants. Given these disadvantages of the BDI-O, a more efficient version of the BDI seems desirable. Two straightforward strategies for paring down the number of items are obvious. As a first strategy for making the BDI more efficient, the number of symptoms could be reduced. This strategy has been proposed by Beck (1978) himself and it has been used by other authors as well (e.g., Kammer, 1983). As a second strategy, the number of items could be reduced.

Proposal of a Simplified Version of the BDI (BDI-S)

In our own work, we decided to employ the second strategy (Schmitt & Maes, 2000). First, we dropped the weight loss symptom of depression because this symptom was found to have the lowest item total correlation in several studies (e.g., Hautzinger, Bailer, Worall, & Keller, 1994; Kammer, 1983). Second, we combined the four statements representing each of the remaining 20 symptoms of the BDI-O into a single statement. Both changes together resulted in a reduction of the number of statements from 84 to 20. Each item of the BDI-S was combined with a six-point frequency rating scale ranging from 0/never to 5/almost always. This response scale format implies that the total score of the BDI-S can vary from a minimum of 0 to a maximum of 100. Heading, instructions, item wording, response-scale, and layout are presented below.

 

How do you feel about life?

This questionnaire is about your present feelings. For each question, please indicate how often you have the mentioned feeling or share the described perspective. If you never have the feeling described in the statement, please circle 0. If you have the feeling almost always, please circle 5. If you have the feeling rarely, circle 1. If you have the feeling often, circle 4. If you have the feeling somewhat more than rarely, circle 2. If you have the feeling somewhat less than often, circle 3.

 

never

almost
always

 

1

I feel sad.

0

1

2

3

4

5

2

I feel discouraged about the future.

0

1

2

3

4

5

3

I feel like a failure.

0

1

2

3

4

5

4

I have a hard time enjoying things.

0

1

2

3

4

5

5

I feel guilty.

0

1

2

3

4

5

6

I feel punished.

0

1

2

3

4

5

7

I am disappointed in myself.

0

1

2

3

4

5

8

I blame myself for my faults and weaknesses.

0

1

2

3

4

5

9

I think about killing myself.

0

1

2

3

4

5

10

I cry.

0

1

2

3

4

5

11

I feel annoyed and irritated.

0

1

2

3

4

5

12

I have no interest in people.

0

1

2

3

4

5

13

I put off making decisions.

0

1

2

3

4

5

14

I worry about my looks.

0

1

2

3

4

5

15

I have to push myself to do things.

0

1

2

3

4

5

16

I don’t sleep well.

0

1

2

3

4

5

17

I feel tired.

0

1

2

3

4

5

18

I have no appetite.

0

1

2

3

4

5

19

I am worried about my health.

0

1

2

3

4

5

20

I have no interest in sex.

0

1

2

3

4

5

 

Psychometric Properties of the BDI-S

In a first study, the psychometric properties of the BDI-S were investigated using a sample of about 2500 participants. The internal consistency of the scale amounted to .90. Latent-state-trait analyses (Steyer, Ferring, & Schmitt, 1992) revealed a high reliability for the scale (.95), a remarkable trait-consistency across two years (.64), a substantial occasion specificity (.26), and a low method specificity (.05). Correlations between the modified BDI and other indicators of well-being, with demographic variables, with the objective and subjective quality of the individual´s employment situation, with belief in a just world and in an unjust world, with belief in control, and with judgments and emotions regarding the employment situation in Germany support the construct validity of the modified BDI. The correlation between the modified BDI and social desirability (-.34) can have different psychological causes and does not necessarily imply a bias by impression management.

Further Evidence on the Construct Validity of the BDI-S

Schmitt, Beckmann, Dusi, Maes, Schiller, and Schonauer (2003) administered the simplified BDI-S, the original BDI-O, and four other depression scales to participants of a demographically heterogeneous sample (n = 200) and to three clinical samples (Major Depressive Disorder, n = 60; Anxiety and Eating Disorders, n = 11; Schizophrenia, n = 40). The reliability of the BDI-S (.93) exceeded the reliability of the BDI-O (.84) and the reliabilities of the remaining depression scales. Both BDI-versions converged well on the level of symptoms (average correlation = .70 in the total sample) and on the level of sum scores (r = .91 in the total sample). Both BDI versions demonstrated equally high correlations with other self-report measures of depression (average correlation = .70) and also equally high correlations with an expert rating of depression (Hamilton-Scale, r = .50). Both versions discriminated depressed individuals about equally well from normal individuals. They also discriminated about equally well between clinical samples. Confirmatory factor analyses showed a slight deviation from perfect measurement equivalence (1.00 ³ r ³ .95). This deviation from perfect equivalence is trivially low with regard to practical applications of the BDI. Schmitt et al. (2003) concluded from this pattern of results that the simplified BDI measures depression equally well but more efficiently than the original BDI. The simplified version is therefore especially suitable for large scale epidemiological screenings.

Norms for the BDI-S

Schmitt, Altstötter-Gleich, Hinz, Maes, and Brähler (2006) computed norm values (percentiles, T-values, z-values) for the BDI-S  based on a sample of N =  4494 German participants (2418 men, 2076 women). Analyses of variance with gender and age as independent variables revealed significant main effects of both factors and a significant interaction. Gender explained 1.5% of the BDI-S-variance, age explained between 0.7% and 2.3% (depending on age groups), and their interaction explained between 0.4% and 2.1% (depending on age groups). Because the gender effect was significant and consistent across all age groups, gender-specific norms were obtained in addition to non-specific norms. Age-specific norms were not determined because the sample sizes of the gender-specific age groups were too small. The sensitivity and the specificity of the BDI-V was estimated for several cut off-values based on a samples from the Schmitt et al. (2003) study. The values are given below.

 

BDI-S cut off score

 

30

35

40

45

50

Sensitvity

.98

.92

.80

.73

.58

Specificity

.85

.91

.93

.95

.96

Schmitt et al. (2006) proposed on the basis of these sensitivity and specificity estimates that a BDI-S score of 35 and above should be considered clinically critical because it indicates the possibility of a severely depressive episode or of major depressive disorder. If such a value is obtained, the BDI-S should be administered a second time two weeks after the first occasion of measurement. If the second BDI-S score again amounts to 35 or above, a careful clinical assessment is highly recommended.

Self-other Agreement in Depression Assessment with the BDI-S

In our most recent study (Schmitt & Hübner, in preparation), we explored the convergent validity of the simplified BDI by comparing self-assessed depression (N = 200) with ratings obtained from acquainted others such as peers, relatives, and spouses. Results demonstrate that the self-other agreement of the simplified BDI is as high as it tends to be for personality questionnaires. Based on Funder’s realistic accuracy model, a number of moderators of self-other-agreement were explored. Acquaintanceship was the most powerful moderator.

References

Beck, A.T. (1978). The depression inventory. Philadelphia: Center for Cognitive Therapy.

Beck, A.T. & Steer, R.A. (1987). Beck Depression Inventory (BDI). San Antonio: The Psychological Corporation Inc.

Beck, A.T., Steer, R.A. & Garbin, M.G. (1988). Psychometric properties of the Beck Depression Inventory: Twenty-five years of evaluation. Clinical Psychology Review, 8, 77-100.

Hautzinger, M., Bailer, M., Worall, H. & Keller, F. (1994). Beck-Depressions-Inventar (BDI). Bern: Huber.

Kammer, D. (1983). Eine Untersuchung der psychometrischen Eigenschaften des deutschen Beck-Depresssionsinventars (BDI). Diagnostica, 29, 48-60.

Schmitt, M., Altstötter-Gleich, C., Hinz, A., Maes, J. & Brähler, E. (2006). Normwerte für das Vereinfachte Beck-Depressions-Inventar (BDI-V) in der Allgemeinbevölkerung. Diagnostica, 52, 51-59.

Schmitt, M., Beckmann, M., Dusi, D., Maes, J., Schiller, A. und Schonauer, K. (2003). Messgüte des vereinfachten Beck-Depressions-Inventars (BDI-V). Diagnostica, 49, 147-156.

Schmitt, M. & Hübner, A. (in preparation). Self-other agreement in depression assessment using a simplified version of the Beck Depression Inventory.

Schmitt, M. & Maes, J. (2000). Vorschlag zur Vereinfachung des Beck-Depressions-Inventars (BDI). Diagnostica, 46, 38-46.

Steyer, R., Ferring, D. & Schmitt, M. (1992). States and traits in psychological as­sess­ment. Eu­ro­pean Journal of Psy­chological Assessment, 2, 79-98.