Journal of Affective Disorders 57 (2000) 261–265www.elsevier.com/ locate / jad

Preliminary communication

The use of the Beck Depression Inventory to screen for depressionin the general population: a preliminary analysis

a a , a a* ´ ´L. Lasa , J.L. Ayuso-Mateos , J.L. Vazquez-Barquero , F.J. Dıez-Manrique ,bC.F. Dowrick

a ´Clinical and Social Psychiatry Research Unit, Marques de Valdecilla University Hospital, University of Cantabria,Avda. Valdecilla s /n, Santander 39008, Spain

bDepartment of Primary Care, University of Liverpool, Liverpool, UK

Received 22 June 1998; received in revised form 10 April 1999; accepted 20 May 1999

Abstract

Objective: The aim of the present paper is to study the performance of Beck’s Depression Inventory (BDI) as a screeninginstrument for depressive disorders in a general population sample.

Methods: 1250 subjects, from 18 to 64 years old, were randomly selected from the Santander (Spain) municipal census. Atwo-stage method was used: in the first stage, all individuals selected completed the BDI; in the second, ‘probable cases’(BDI cut-off $ 13) and a random 5% sample of the total sample with a BDI score less than 13 were interviewed bypsychiatrists using the Schedules for Clinical Assessment in Neuropsychiatry (SCAN), which generates diagnoses ofdepressive disorders.

Results: Our data confirm the predictive value of the selected cut-off point (12 /13): 100% sensitivity, 99% specificity,0.72 PPV, 1 NPV, and 98% overall diagnostic value. The area under ROC (AUC) was found to be 0.99. There were nostatistical differences in terms of sex or age. We conclude that the BDI is a good instrument for screening depressivedisorders in community surveys. 2000 Elsevier Science B.V. All rights reserved.

Keywords: BDI; Predictive value; Community survey

1. Introduction or depth of the depressive symptomatology in pa-tients with psychiatric disorders, it is now widely

There are now more than 50 instruments available used as a screening instrument to detect depressionfor the detection of depressive disorders (Wittchen in clinical practice and research projects (Beck et al.,and Essau, 1990); one of the better known is Beck’s 1988). Self-report questionnaires, such as the BDI,Depression Inventory (BDI) (Beck et al., 1961). are particularly suitable in these contexts; in fact, thisAlthough initially developed to measure the intensity instrument is generally considered one of the best

screening tools available for assessing depression in*Corresponding author. both psychiatric and medical settings (McDowell and

0165-0327/00/$ – see front matter 2000 Elsevier Science B.V. All rights reserved.PI I : S0165-0327( 99 )00088-9

262 L. Lasa et al. / Journal of Affective Disorders 57 (2000) 261 –265

Newell, 1996). There is, however, certain evidence and 64 years old, randomly selected from thesuggesting that the BDI performs better as a screen- municipal census of Santander (capital of Cantabria).ing instrument in psychiatric than in normal popula- Of these, 623 (49.48%) were men and 627 (50.16%)tions, compared with clinical evaluation. We have to were women; as to age, 349 were 18 to 29 years oldpoint out, however, that this evidence is not derived, (27.92%) and 901 were 30 to 64 (72.08%). Noas it should be, from studies based on a non-biased significant sex or age differences were found in asample of normal populations, using a reliable comparison of Santander’s total population with thestructured psychiatric interview for clinical evalua- sample selected for the study. During the screeningtion (e.g. the PSE-9, the SCAN or the SCID). To our phase, all subjects were visited by a team of special-knowledge, there is no published study examining ly trained interviewers. During a single session, eachthe BDI’s predictive values for the detection of person was asked to complete the BDI and answer adepression in a representative sample of the working- variety of questions concerning sociodemographicage general population that uses a reliable psychiatric variables, life events and healthcare services usedinterview as a validation instrument. Thus, if we over the last month. The criteria for the selection ofwish to adopt this questionnaire as a screening subjects to be included in the second phase of theinstrument for research use, we should first try to study were: (1) all subjects who scored 13 or moreverify its criterion validity with an appropriate on the BDI (‘probable positives’) in the first stage;methodological design. and (2) a random 5% sample of the total sample with

The objective of the present study was to assess, a BDI score less than 13. This phase was conductedin a representative sample of the general population by psychiatrists using the SCAN, which generatesand using the Schedules for Clinical Assessment in diagnoses of depressive disorders based on ICD-10

´Neuropsychiatry (SCAN; Vazquez-Barquero et al., (WHO, 1992).1994) system as the criterion against which the For the statistical analysis, the SPSS Programpredictive value of the different cut-off points of the (v.7.0 for Windows 95) was used to obtain 2 3 2Spanish version of the BDI will be explored. tables after weighting to allow for the two-phase

sampling (Dunn et al., 1999). The TWOBYTWOAnalyzer Program (v. 1.0) (Centor and Keightley,

2. Method 1992) was used to obtain predictive values fordifferent BDI cut-off points (sensitivity, specificity,

Data for the present study were obtained from the positive and negative predictive value, and overallSpanish site of the ODIN project, a multi-centre diagnostic value). The ROC area using weightedepidemiological study designed to provide reliable analysis was calculated with Stata (StataCorp, 1997).and valid data on the prevalence, risk factors andoutcome of depressive disorders within the EuropeanUnion, based on an epidemiological sampling frame- 3. Resultswork, as well as to assess the impact of psychologi-cal interventions on the outcome of depression. The distribution of the BDI scores in the totalDetailed descriptions of this project’s aims and sample population is shown in Fig. 1. A group of 52methods have been presented elsewhere (Dowrick et (4.16%) subjects scored a BDI total $ 13; of these,al., 1998; Ayuso-Mateos et al., 1999). For the seven refused to take part in the second phase andpresent study, we adopted a two-stage screening one died before the interview date. Forty-four (12process. Potential cases of depressive illness and men and 32 women) subjects with BDI $ 13 and 62depressive adjustment disorders were identified using (14 men and 48 women) subjects with BDI , 13the BDI. A threshold of 12/13 was chosen initially participated in the diagnostic interview. No subjectto screen for this disorder (Nielson and Williams, with BDI , 13 was diagnosed with depression during1980), and in the second phase the diagnosis was the SCAN interview; 32 individuals with BDI $ 13confirmed with a structured psychiatric interview. had a depressive disorder.The sample comprised 1250 individuals, between 18 Table 1 shows the weighted predictive value of

L. Lasa et al. / Journal of Affective Disorders 57 (2000) 261 –265 263

Fig. 1. Distribution of BDI scores in the total sample population.

Table 1 of a scale used for screening purposes ought toWeighted predictive value of different BDI cut-off points maximise sensitivity, even if it limits specificity

a bCut-off Sensitivity Specificity PPV NPV Overall somewhat, especially if the test is simple, convenientpoint diagnostic and inexpensive (Zarin and Earls, 1993).

value Beck ruled out strict adhesion to cut-off points for12/13 100% 99% 0.72 1 98% the BDI, preferring that they be chosen according to13/14 90% 99% 0.80 0.99 99% the type of study. He suggested that total scores of14/15 90% 99% 0.82 0.99 99%

less than 10 do not show depressive disorders;15/16 84% 99% 0.81 0.99 98%between 10 and 18, from mild to moderate depres-16/17 78% 99% 0.86 0.99 98%

17/18 75% 99% 0.88 0.99 98% sion; between 19 and 29 from moderate to severe;18/19 62% 99% 0.86 0.98 98% and scores of more than 30 indicate severe depres-

a sion. He also pointed out that for psychiatric patients,PPV, positive predictive value.b NPV, negative predictive value. a 12/13 cut-off point could be appropriate for

identifying depression, whereas a 9 /10 cut-off pointdifferent cut-off points. The cut-off of 12/13 ob- could be more suitable for medical patients (Becktained 100% sensitivity, 99% specificity and a posi- and Beamesdefer, 1974).tive predictive value of 0.72. The latter improved Beck et al. (1988) reviewed studies on the BDI’swhen the cut-off point was higher, but in general, psychometric properties published during the last 25predictive value was very good at the cut-off score years. They did not find that any performed well on achosen initially for the study. The area under the stratified sample of the general population. TheROC curve was found to be 0.997, with no statistical present study is the first, as far as we know, on thedifferences in terms of age or gender. predictive value of the BDI conducted using a

randomised general population sample.In our sample, we confirmed that subjects with

4. Discussion BDI scores of less than 13 do not have depression(100% sensitivity; negative predictive value: 1).

Screening instruments have become important Conde and Chamorro (1976), using the Spanishtools for identifying ‘probable cases’, but most of version of the BDI, recommended the same cut-offthem have been developed in specific samples (i.e. point in a study comprising in-patients and out-psychiatric patients, the medically ill) and need patients with depression or alcoholism and normaladjustment, in their predictive values, when applied subjects. With this cut-off point (12 /13), specificityto particular samples and studies. The cut-off point and positive predictive value hold up appropriate

264 L. Lasa et al. / Journal of Affective Disorders 57 (2000) 261 –265

values (99% and 0.72, respectively). As a research decision about the clinical relevance of any symp-screening tool, the 12/13 cut-off would seem most tom, they have to follow the specific definitionsappropriate due to the high sensitivity. provided in the SCAN glossary. The data collected

Boyd et al. (1982) studied the predictive value of during interviews are coded on a set of scoringthe CES-D (Centre for Epidemiological Studies — sheets and later processed in a diagnostic computerDepression Scale) in a randomised general popula- program (CATEGO). This process makes it unlikelytion sample, and found that to achieve 100% sen- that knowledge of interviewed subjects’ BDI statussitivity they had to lower the cut-off point to values could have a significant impact on final diagnoseswhere specificity (70%) and positive predictive generated by the CATEGO.values (14%) were unacceptable. Face-to-face administration of the BDI may lead

If a scale is going to be used as a screening subjects to provide less negative answers — andinstrument in the general population, its validation hence have lower scores — than when completingproperties must be independent of age and gender. BDIs administered anonymously or by post. ThisThe AUC, in our study, showed that the BDI is an hypothesis will be tested by assessing the PPV of theinstrument with a generally good diagnostic preci- 12 /13 cut-off at the other four ODIN centres, whichsion, and that it is independent of its subjects’ age or have used an initial postal survey rather than agender. With our results in hand, we can firmly state face-to-face one. This analysis will also test William-that the BDI is a good instrument for detecting son and Williamson’s (1989) proposition that theredepressive disorders in the general population. may be large normative differences in BDI scores

One of the limitations of the present study is that between different study populations. Subsequentthe researcher in charge of the diagnostic interview, analysis of the complete ODIN dataset will providealthough initially blind to the BDI scores, later further information on the optimal cut-off scores forlearned some patients’ scores from the subjects postal and face-to-face surveys in different popula-themselves. The study was part of a complex re- tions.search project which, in addition to an epidemiologi-cal survey, included a person-centred interventiontrial with subjects whose depressive disorders had Acknowledgementsbeen identified during the epidemiological phase.This aspect of the study was explained to them The ODIN study received financial support fromduring the initial contact in order to obtain their the European Commission’s Biomed 2 Programmecollaboration, and some of the subjects who went on (Contract BMH4-CT96-1681) and the Spanishto the second phase disclosed, during the diagnostic Ministry of Health (Fondo de Investigacionesinterviews, why they were there: either having a BDI Sanitarias 96/1798). Dr Lasa is a FIS Researchscore above 12, or being part of the control group. Fellow (BAE 97/5241). We thank Prof. GrahamThus, in some cases the psychiatrists knew which Dunn for his helpful comments.subjects had scored above the BDI cut-off, andwhich were from the 5% sample.

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