evaluation of depression in schizophrenia: psychometric properties of a french version of the...

Ž .Psychiatry Research 89 1999 123]132

Evaluation of depression in schizophrenia:psychometric properties of a French version of the

Calgary Depression Scale

Christophe Lancona,U, Pascal Auquier b, Gilles Reinea, Mondher Toumib,Donald Addingtonc

aDepartment of Psychiatry, CHU Sainte Marguerite, Marseille, FrancebDepartment of Public Health, La Timone Hospital, Marseille, France

cDepartment of Psychiatry, Uni ersity of Calgary, Calgary, Alberta, Canada

Received 30 November 1998; received in revised form 5 July 1999; accepted 10 September 1999

Abstract

Ž .The aim of this study was to determine the psychometric properties especially validity and reliability of theŽ .French language version of the Calgary Depression Scale for Schizophrenia CDSS in schizophrenic patients.

Ninety-five subjects who met DSM-IV criteria for schizophrenia were enrolled. The studies of the internal structuralŽ . Žvalidity and of the reliability internal consistency showed that some items from the CDSS early awakening and

.guilty ideas of reference must be discussed in the constitution of this scale. The total score of the CDSS wasŽ .significantly correlated with the MADRS total score, the HDRS total score, and the depression item G6 on the

PANSS, which suggests that the CDSS is a valid instrument for the assessment of depression in schizophrenia. Theexistence of a significant correlation between the CDSS total score and the PANSS positive sub-scale suggests apossible relationship between positive and depressive symptoms in schizophrenia. Q 1999 Elsevier Science IrelandLtd. All rights reserved.

Keywords: Calgary Depression Scale; Psychometrics; Cross-cultural; Positive symptoms

U Corresponding author. Service Hospitalo-Universitaire de Psychiatrie d’adultes, CHU Sainte Marguerite, 270 Bd de SainteMarguerite, 13274 Marseille Cedex 09, France. Tel.:q33-04-9174-4051.

Ž .E-mail address: [email protected]. C. Lancon

0165-1781r99r$ - see front matter Q 1999 Elsevier Science Ireland Ltd. All rights reserved.Ž .PII: S 0 1 6 5 - 1 7 8 1 9 9 0 0 0 9 7 - 9

( )C. Lancon et al. r Psychiatry Research 89 1999 123]132124

1. Introduction

In order to reduce the heterogeneity ofschizophrenia, a dichotomous model distinguish-ing positive and negative forms of the disease was

Ž .proposed by Crow 1980 . While this model hasgiven rise to numerous studies, it appeared neces-sary to distinguish other symptomatic dimensionsin order to account for the clinical signs andsymptoms observed in the late course of

Ž .schizophrenia Lindenmayer et al., 1994 . Forsome authors, a depressive dimension is to be

Ž .distinguished Kay and Sevy, 1990 . The fre-quency of depressive disorders in schizophrenicshas been variously evaluated, depending on the

Ž .phase of the disease Siris, 1990 . The prognosticvalue of the depressive disorders has been widely

Ž .debated Siris et al., 1984 .Since the assessment of depression in the ad-

vanced course of schizophrenia would be con-sidered as an important factor, several methodo-logical problems require discussion. There aremarked overlaps between the signs and symptomsof depression and extrapyramidal or negative

Ž .symptoms Prosser et al., 1987 . Moreover, theevaluation of depression in schizophrenics hasgenerally been conducted using depression ratingscales developed in non-schizophrenic depressed

Žpatients Addington and Addington, 1989;.Addington et al., 1990 . The validity of those

scales in schizophrenic patients requires discus-Ž .sion Goldman et al., 1992 .

In order to resolve these methodological prob-Ž .lems, Addington et al. 1990 developed a scale

for assessing depressive symptoms in schizophren-ics. The Calgary Depression Scale for Schizophre-

Ž .nia CDSS was initially developed from a princi-pal component analysis of the items of the Pres-

Ž .ent State Examination PSE; Wing et al., 1974and the Hamilton Depression Rating ScaleŽ .HDRS; Hamilton, 1960 . A structured interviewand precise rating guide were subsequently used.The current scale consists of nine items. Thevalidity and reliability of the CDSS have been

Žwell documented by Addington Addington et al.,.1992, 1993, 1994, 1996 .

Few data are currently available on the psycho-metric properties of the CDSS in other popula-tions of schizophrenic patients than Addington’s

Ž .one Collins et al., 1996; Bressan et al., 1998 . Thehighly satisfactory psychometric properties of theCDSS in the English language version led us toconduct a preliminary study to investigate certain

Žpsychometric properties mainly structural valid-. Žity of the French language version Bernard et

.al., 1998 . The present work is a study of theŽ .structural validity internal and external and reli-

ability of the French language version of theCDSS, together with an investigation of its sensi-tivity and specificity, in a larger population ofschizophrenic patients than that of Bernard et al.Ž .1998 .

2. Materials and methods

2.1. Subjects

The patients enrolled in the study were re-cruited from an in- and out-patient populationtaking part in a long-term follow-up program. Allthe subjects satisfied the formal criteria for adiagnosis of schizophrenia according to DSM-IVŽ .American Psychiatric Association, 1994 and gavetheir written consent to take part in the study.

Patients presenting another diagnosis on axis Iof DSM-IV, a decompensated organic diseaseŽ .particularly neurological disease , drug abuseŽ .DSM-IV criteria , mental retardation, a historyof mood regulating or electroconvulsive therapy,

Žpatients on atypical antipsychotics clozapine,.olanzapine or risperidone and subjects whose

native language was not French were not eligiblefor the study.

2.2. Procedures

When the patients had given their consent toparticipate in the study, all the evaluations wereconducted by experienced research psychiatristsin the course of the same day.

Schizophrenia was diagnosed as per the formalcriteria according to DSM-IV. The inclusion cri-teria were completed by review of the medicalfiles.

In order to characterise the degree ofschizophrenic symptoms, the Positive and Nega-

( )C. Lancon et al. r Psychiatry Research 89 1999 123]132 125

Ž .tive Syndrome Scale PANSS was scored accord-Ž .ing to the recommendations of Kay et al. 1987

Ž .by an experienced rater CL , who was blind tothe results obtained with the depression ratingscales. Extrapyramidal symptoms were evaluatedusing the Extrapyramidal Symptom Rating ScaleŽ . Ž .ESRS of Chouinard et al. 1980 , by the samepsychiatrist, after completing the PANSS.

The evaluation of depressive symptoms wasŽ .conducted by a research psychiatrist GR using

Žthe French language versions of the CDSS Ad-. Ždington et al., 1992 , the HDRS 17-item version;

˚.Hamilton, 1967 , the Montgomery and AsbergŽDepression Rating Scale MADRS; Montgomery

˚ .and Asberg, 1979 and the Psychomotor Depres-Ž .sive Slowness Scale PDSS; Widlocher, 1981 . A¨

structured interview was conducted to evaluatedepressive symptoms. The interview was derivedfrom the interview guide proposed by Addington

Ž .et al. 1993 . The author of the scale, who istotally bilingual, checked the French translation

Ž .of the CDSS. The author D. Addington hasdone the back-translation of the CDSS.

2.3. Statistical analyses

The analysis conducted aimed to explore firstthe validity of the CDSS and secondly its reliabil-ity. The content validity was not reappraised.

The internal structural validity was investigatedby conducting: an item analysis; a study of thebetween-item correlation matrix; a study of thecorrelation of the items with the overall score;and principal components analysis. The proce-dure employed enabled extraction of the initialfactors. The cut-off for factor extraction was aneigenvalue )1.5, providing that the total vari-

Žance explained was)40% the cut-off was set at1.5 in order to strengthen the conclusions of the

.factorial analysis . This decision making criterionis admissible insofar as the number of subjectswas limited compared to the number of itemsŽ .Nunnally, 1994 . Various approaches to the fac-

Žtorial structure were explored varimax, quarti-.max and equimax rotation in order to obtain

optimal confirmation of the hypothesis of unidi-

mensionality suggested by our initial resultsŽ .Bernard et al., 1998 . Only the items whose com-munality exceeded 0.5 were retained.

The referential external structural validityŽ .Nunnally, 1994 was investigated by study of theSpearman correlation coefficients between theoverall score and the nine CDSS items and item

Ž .G6 of the PANSS depression , considered thegold standard in the absence of other criteria.This approach was completed by study of theSpearman correlation coefficients between theCDSS items and the PANSS, PDSS and ESRSscores.

Convergent trait validity was investigated bystudying the Pearson correlation coefficientsbetween the CDSS items and the MADRS, HDRSand PDSS scores.

The analysis of sensitivity and specificity wasalso conducted on the MADRS and HDRS scores.Using the cut-off point defined by that analysis,we compared the main characteristics of the de-pressed and non-depressed patients using analysis

Ž .of variance ANOVA .The reliability of the scale was studied by com-

puting the Cronbach a coefficients.

3. Results

3.1. Population

Ninety-five subjects meeting the diagnostic cri-teria for schizophrenia according to DSM-IV

Ž .completed the study: 77 in-patients 81% and 18Ž . Ž .out-patients 19% ; 30 women 32% and 65 men

Ž . Ž .68% . The mean age was 33.9 years S.D.s11.7 .The mean duration of disease progression was

Ž .10.3 years S.D.s9.8 . The mean number of hos-Ž .pitalisations was 7.6 S.D.s9.5 and the mean

duration of hospitalisation for the hospitalisedŽ .patients was 41.2 days S.D.s59.7 . All the

patients were receiving neuroleptic treatmentprior to inclusion in the study. The mean age atwhich the first neuroleptic treatment was initiated

Ž .was 23.8 years S.D.s6.3 . The mean dosage ex-Žpressed as chlorpromazine equivalents Foster,

.1989 on the day of evaluation was 853.2 mgrdayŽ .S.D.s645.8 .


Table 1aClinical evaluations

Ž .Mean S.D. Min]max

Ž .CDSS total 7.5 5.1 0]22Ž .MADRS total 17.9 9.1 0]43Ž .HDRS total 18.1 6.5 4]32Ž .PDSS total 18.7 9.5 3]43Ž .PANSS-P 20.1 7.1 10]38Ž .PANSS-N 24.7 5.6 13]36Ž .PANSS-GP 48.4 9.8 23]78Ž .PANSS total 93. 17.8 48]145Ž .ESRS V 0.7 1.2 0]6Ž .ESRS VI 3.1 1.2 0]5Ž .ESRS VII 0.4 0.8 0]3Ž .ESRS VIII 1.6 0.8 0]3

aAbbre¨iations: PANSS-P, positive sub-scale of the PANSS;PANSS-N, negative sub-scale of the PANSS; PANSS-GP, gen-eral psychopathology sub-scale of the PANSS; ESRS V, clini-cal global impression of dyskinesia; ESRS VI, clinical globalimpression of severity of parkinsonism; ESRS VII, clinicalglobal impression of dystonia; and ESRS VIII, stage of parkin-sonism.

The clinical evaluations are represented inTable 1.

3.2. Validity

3.2.1. Internal structural ¨alidity3.2.1.1. Item analysis. The item analysis con-

ducted showed a relatively homogenous distribu-tion of the responses for each of the items al-

though the least severe response modality wasglobally over-represented while the most severeresponse modality was globally under-repre-sented. This was particularly true for the items

Ž . Ž .early awakening C7 and suicide C8 for whichthe discrimination indices were less than 0.70. Forthe other items, the discrimination index wasgreater than 0.75.

Study of the correlation matrix shows that allthe items were significantly correlated with each

Žother except for item C4 guilty ideas of refer-.ence which showed the lowest correlation coef-

Ž .ficients with item C5 pathological guilt , C6Ž . Ž .morning depression and C7 early awakening

Ž .and except for item C7 early awakening withŽ .item C9 observed depression . All the items were

significantly correlated with the total CDSS scoreand all the correlations were greater than 0.5.However, when the correlations of each item withthe total score excluding the item studied were

Žinvestigated, the correlations for item C4 guilty. Ž .ideas of reference and C7 early awakening were

Ž .very weak F0.35 .3.2.1.2. Factorial analysis. In accordance with

the predefined selection criterion, the principalcomponents analysis addressed two factors ex-plaining 54% of the total variance. These itemswere strongly represented on the first axis andcontributed little to the make-up of the second

Žwith the exception of items C4 guilty ideas of

Table 2Principal components analysis of the CDSS

Initial analysis Varimax

1 2 1 2

C1, depression 0.82 0.06 0.80 y0.15C2, hopelessness 0.77 0.06 0.62 0.30C3, self-depreciation 0.73 y0.35 0.59 0.57C4, guilty ideas of reference 0.45 y0.52 0.31 0.64C5, pathological guilt 0.60 0.21 0.27 0.76C6, morning depression 0.65 0.22 0.57 0.27C7, early wakening 0.47 0.67 0.04 0.69C8, suicidal 0.65 0.01 0.47 0.45C9, observed depression 0.69 y0.24 0.59 0.49Eigenvalue 3.88 1.00 2.46 2.42% of the variance 43.1 11.2 27.3 26.9


. Ž .reference and C7 early awakening . This ten-Ždency was accentuated by Varimax rotation Ta-

.ble 2 .

3.2.2. External structural älidity3.2.2.1. Referential external structural älidity.

Ž .The score of item G6 of the PANSS depressionwas significantly correlated with all of the CDSSitems, as well as the total score. Items C1, C2 and

ŽC5 had high-level correlations rs0.63, rs0.57.and rs0.53, respectively while items C3 and C8

Žshowed low-level correlations rs0.36 and rs.0.36, respectively . The total score correlation was

always higher than that of each of the items.With regard to the analysis of sensitivity and

specificity, scores G25 for total HDRS scorewere retained as is proposed in the literatureŽ .Hamilton, 1967 . A cut-off of six for the CDSS

Ž .was selected Fig. 1 . The distributions were rela-tively identical with those for the total MADRSscores.

3.2.2.2. Non-referential external structural älidity.Conërgent trait älidity. The mean score of theCDSS was significantly correlated with that on

Ž . Žthe MADRS rs0.83, P-0.001 , HDRS rs. Ž .0.70, P-0.001 , PDSS rs0.29, P-0.02 and

Ž . Žwith item G6 of the PANSS depression rs0.80,.P-0.001 .

The CDSS items showed correlation coeffi-cients with the MADRS score that were all greater

Ž .than 0.45 except for items C4 rs0.27 and C8Ž .rs0.42 . The correlation coefficients with theHDRS score were all greater than 0.4 except for

Ž . Ž .items C4 rs0.26 and C8 rs0.37 .w ŽWhen the PDSS sub-scores motor PDSSm,

. Žfirst six items ; ideational PDSSi, items seven and. Ž .eight ; and subjective PDSSs, last six items

Ž .xLanglois-Thery et al., 1994 , were studied sepa-rately, a significant positive correlation was onlyobserved between the total CDSS score and the

Ž .PDSS subjective sub-score rs0.56, Ps0.0001 .The total score of the CDSS was not signifi-

Žcantly correlated with the ESRS V clinical global. Žimpression of dyskinesia , ESRS VI clinical global

.impression of severity of parkinsonism , ESRSŽ .VII clinical global impression of dystonia and

Ž . ŽESRS VIII scores stage of parkinsonism rs.0.16, 0.25, 0.13 and 0.20, respectively, NS .

Nomological älidity. Patients with a total CDSSŽscore G6 were considered as depressed 48

.patients and those with a score -6 as non-de-Ž .pressed 47 patients . The depressed patients had

Ž .Fig. 1. Determination of the CDSS cut-off point sensitivity and specificity with the HDRS total score)25.


significantly higher scores for total PANSS,PANSS positive sub-scale and general psy-chopathology sub-scale than the non-depressedpatients. No significant difference between thetwo groups was observed for the PANSS negativesub-scale or for the extrapyramidal symptom

Ž .scores Table 3 .The total CDSS score was significantly corre-

Ž .lated with total PANSS r s 0.33, P - 0.01 ,Ž .PANSS positive sub-scale rs0.29, P-0.02 and

Žgeneral psychopathology sub-scale rs0.39, P-.0.001 scores. No significant correlation with the

PANSS negative sub-scale score was observed.With regard to the sociodemographic data, the

total CDSS score was only significantly correlatedŽwith the duration of disease progression rs0.24,

.P-0.05 .

3.3. Reliability

3.3.1. Internal consistencyOnly internal consistency was considered in

this study. Inter-rater reliability and stability over-

time have already been studied and reported else-Žwhere Addington et al., 1993; Bernard et al.,

.1998 .The internal consistency of the CDSS was good

Ž . Ža : 0.82 . All the items except C4 guilty ideas of. Ž .reference and C7 early awakening are neces-

Ž .sary for the construction of the scale Table 4 .

4. Discussion

The main aim of the study conducted was toverify the psychometric properties of the French

Žlanguage version of the CDSS scale validity and.reliability . The study we have conducted has

some methodological limitations. The number ofŽ .patients 95 enrolled is low and therefore limits

the generalisation of our results. The patientsincluded are at different phases of the diseaseŽ .acute and chronic patients and the relationshipsbetween the CDSS score and the schizophrenicmanifestations evaluated with the PANSS may be

Ždifferent in acute and chronic patients Adding-

Table 3aŽ . Ž .Comparison between depressed CDSS total)6 and non-depressed CDSS total-6 schizophrenic patients

Depressed Non-depressed PŽ . Ž . Ž .ns48 ns47 ANOVAMean"S.D. Mean"S.D.

PANSSPANSS total 98.2"15.7 86.0"18.6 0.005PANSS positive 22.0"7.1 17.5"6.6 0.01PANSS negative 24.8"5.4 24.6"5.9 NSPANSS general psychopathology 54.4"8.7 44.0"9.9 0.002

MADRSMADRS total 22.9"8.0 11.4"5.4 -0.001

HDRSHDRS total 21.1"5.5 13.8"5.2 -0.001

ESRSESRSV 0.8"1.2 0.6"1.1 NSESRS VI 3.2"1.1 2.8"1.2 NSESRS VII 0.5"0.8 0.3"0.7 NSESRS VIII 1.6"0.8 1.4"0.7 NS

aAbbre¨iations: ESRS V, clinical global impression of dyskinesia; ESRS VI, clinical global impression of severity of parkinsonism;ESRS VII, clinical global impression of dystonia; and ESRS VIII, stage of parkinsonism.


Table 4Ž .Internal reliability of the CDSS Cronbach a

aMean if item Item } total P a if itemdeleted correlation deleted

C1, depression 6.21 0.72 -0.01 0.78C2, hopelessness 6.47 0.65 -0.01 0.79C3, self-depreciation 6.39 0.60 -0.01 0.79C4, guilty ideas of reference 6.63 0.58 -0.01 0.83C5, pathological guilt 6.55 0.48 -0.02 0.81C6, morning depression 6.73 0.36 -0.02 0.80C7, early wakening 6.78 0.54 -0.01 0.82C8, suicidal 3.95 0.54 -0.01 0.80C9, observed depression 6.83 0.55 -0.01 0.80CDSS total as0.82

a Significance of the Pearson correlation coefficient.

.ton et al., 1994 . The fact that the same raterperformed the CDSS, HDRS, MADRS and PDSSon the same patients on the same day can inducea halo effect in the rater. To limit this effect, thedepression scales were not all administered in thesame order for all the patients.

The results obtained in our population con-firmed most of those reported by Addington et al.Ž .1992, 1993 in their various studies validating theEnglish language version of the CDSS. In thelight of the results obtained in our population, itis, nonetheless, appropriate to discuss the reliabil-ity and validity of the scale.

The study of the structural validity of the CDSSraised the question of the unidimensional charac-ter of the scale. The principal components analy-sis conducted generated a unifactorial solutionexplaining 43% of the total variance. The crite-

Ž .rion used eigenvalue )1.5 for factor selectioncould be discussed. Other criteria are proposed,such as Cattell score test or Horn parallel analy-

Ž .sis Nunnally, 1994 . None of those methods hasŽ .demonstrated its superiority Nunnally, 1994 . The

Žvarious approaches adopted varimax, equimax.and quartimax did not all yield the same factorial

Ž .solution } items C4 guilty ideas of referenceŽ .and C7 early awakening showed important con-

tributions on the second axis. The unidimensionalcharacter of the CDSS has, nonetheless, been

Ž .suggested by Addington et al. 1992, 1993 whofound a single factor following principal compo-

nents analysis of CDSS scores in a population of150 schizophrenic patients. In order to validatethe solution, the authors conducted a confirma-tory analysis, which was in favour of a unidimen-sional nature of the CDSS. However, Addington

Ž .et al. 1996 conducted a new analysis in a popu-lation of 112 in-patients examined on admissionŽ . Ž .T1 and 3 months post-admission T2 . Threefactors explaining 67% of the total variance wereisolated from that population. The first factorexplained 43.1% of the total variance. This factor,

Ž .consisting of the items depressive mood C1 ,Ž . Ž .despair C2 , self-depreciation C3 , pathological

Ž . Ž .guilt C5 and observed depression C9 , showedthe greatest stability over time. In contrast, thecomposition of the other two factors was not thesame at the two evaluation time points. The items

Ž .guilty ideas of reference C4 , early awakeningŽ . Ž .C7 and suicide C8 were projected on one orthe other of the factors. While the internal con-

Žsistency of the first factor isolated was high as.0.84 , that for the other factors was relatively low

Ž .a-0.65 , irrespective of evaluation time point.Lastly, the characteristic value of the third factorisolated was less than 1 at both evaluation timepoints. With reference to the criteria recom-

Ž .mended by Harris 1975 for whom factors isolatedfrom a principal components analysis are re-quired to have a characteristic value greater than2 and be composed of fewer than five items, theunidimensional structure of the CDSS may be


retained. The items guilty ideas of reference andearly awakening must be discussed for the con-struction of the CDSS. The item analysis con-firmed the difficulties encountered in attachingsome items to the first dimension we isolated.The items guilty ideas of reference and earlyawakening showed low-level or no correlation withthe other items constituting the scale.

The internal consistency study strengthens theresults of the structural validity study, which weconducted. The internal consistency of the CDSSwas high in our population with regard to the

Ž .results of Addington et al. 1993 obtained for in-Žand out-patients. However, item C4 guilty ideas

.of reference and, to a lesser extent, item C7Ž .early awakening would appear to contribute lessto the CDSS. Similarly, if the unidimensional

Žstructure proposed by Addington et al. 1992,.1993 is retained, the internal consistency of the

Ž .solution is good as0.82 and all the items areconsistent with each other, with the exception of

Ž .the items guilty ideas of reference C4 and earlyŽ .awakening C7 . In contrast, in a two-dimensional

Žstructure, the first factor isolated C1, C2, C3, C5,.C6, C8 and C9 retains good internal consistency

Ž .as0.83 while the second factor consisting onlyŽ .of two items C4 and C7 shows low internal

Ž .consistency as0.19 .These results confirm the unidimensional char-

acter of the CDSS. However, a revised version ofŽthe scale containing only seven items C1, C2, C3,

.C5, C6, C8 and C9 seems to have superior inter-nal consistency to that of the 9-item version.

The validity of the CDSS as an instrument formeasuring depression in schizophrenic patientswas confirmed by the existence of strong signifi-cant correlations between the CDSS and conven-tional depression rating scales such as the HDRSand the MADRS and the global rating of depres-sion using item G6 of the PANSS. It should be

Ž .stressed that item C4 guilty ideas of referencewas the CDSS item with the lowest correlation

Ž .coefficients rs0.25 and rs0.26, respectivelywith the MADRS and HDRS confirming the re-sults of the principal components analysis that we

Ž .conducted. Addington et al. 1992 have alreadyreported significant correlations between total

CDSS score, HDRS score, Beck Depression In-ventory score and ‘depressive’ score on the BPRS.

The relationships between the CDSS and thePDSS appear to be more complex. The correla-tion between the total CDSS score and the total

ŽPDSS score was relatively high rs0.38, P-.0.001 . When the PDSS sub-scales scores were

studied, only the correlation between the subjec-tive sub-score and the total CDSS score was sig-

Ž .nificant rs0.56, P-0.001 while there was nocorrelation with the PDSS motor and ideationalsub-scores. These results are to be compared to

Ž .those reported by Langlois-Thery et al. 1994who showed, in a population of 53 treated schizo-phrenics, that only the PDSS subjective sub-scorecould be considered as a pertinent indicator of

Ž .depressive symptoms. Langlois-Thery et al. 1994 ,studying the correlation coefficients between theMADRS, PDSS, PANSS negative sub-scale andextrapyramidal symptoms score based on theESRS, showed that only the PDSS subjectivesub-score was significantly correlated with thetotal MADRS score. Conversely, the PDSS motorsub-score was significantly correlated withakathisia and the PDSS ideational sub-score wassignificantly correlated with negative symptoms. Itwould, thus, appear that the subjective sub-scoremeasures depressive symptoms independently ofextrapyramidal and negative symptoms. In ourstudy, the positive correlation between total CDSSscore and the PDSS subjective sub-score lendsfurther credence to the idea that the CDSS is afairly specific instrument for the evaluation ofdepressive symptoms in schizophrenic patients.

While the CDSS appears to be a valid instru-ment for measuring depressive symptoms, its rela-tionships with, first, the other symptomatic di-mensions of schizophrenia and, second, the ex-trapyramidal symptoms induced by neuroleptics

Ž .require discussion. Addington et al. 1993 in apopulation of 31 chronic schizophrenic patients,found no significant correlation between the totalCDSS score and the extrapyramidal effects of

Žneuroleptics evaluated using the Simpson]Angus. Žscale or negative symptoms evaluated using the

.Negative Symptom Scale . However, the same au-Ž .thors Addington et al., 1994 in a population of

Ž150 schizophrenic patients 100 out-patients and


.50 in-patients showed a weak but significant cor-Ž .relation rs0.33, P-0.05 between the total

CDSS score and the PANSS negative sub-scalescore. This correlation was found only for hospi-talised schizophrenic patients. The authors do notindicate the stage of disease progression in thepatients. While these results suggest that, depend-ing on the schizophrenic patients studied, theCDSS is in part contaminated by projection of thenegative symptoms of schizophrenia, the confir-matory analysis conducted by Addington et al.Ž .1994 is nonetheless in favour of the indepen-dence of the mood disorders evaluated using theCDSS and the negative symptoms of schizophre-nia evaluated using the PANSS negative sub-scale.

In the study of 112 schizophrenic patients eval-uated on admission and 3 months post-admission,

Ž .Addington et al. 1996 found a significant corre-Žlation between factor 2 suicide, ideas of refer-

.ence and the PANSS positive sub-scale at thetwo evaluation time points. No significant correla-tion between the CDSS and the total score on theSimpson]Angus scale was found.

The relationship between the CDSS and thepositive symptoms of schizophrenia concurs withthe results of our study. We demonstrated a sig-nificant correlation between the total CDSS score

Žand the PANSS positive sub-scale score rs0.28,.P-0.05 and the general psychopathology sub-

Ž .scale score rs0.39, P-0.01 . In contrast, thecorrelation between the CDSS and the PANSSnegative sub-scale score was not significant. As

Ž .suggested by Addington et al. 1996 , some CDSSŽ .items guilty ideas of reference may be con-

sidered positive symptoms of the disease. Thisstatement may, in part, explain for those authorsthe association between the CDSS and the PANSSpositive sub-scales. This point of view has to bediscussed because we have studied the correlationbetween the CDSS total score without the item‘guilty ideas of reference’ and the positive sub-scale of the PANSS and have again found a

Ž .significant correlation rs0.23, P-0.05 . SeveralŽauthors Green et al., 1990; Addington and

.Addington, 1992 have shown that there is a sig-nificant relationship between the presence of sui-cidal ideas and the presence of positive symptoms

and that the onset of depressive episodes inschizophrenic patients is frequently accompaniedby an increase in positive symptoms.

The study of sensitivity and specificity that weconducted confirmed the cut-off point of six de-

Ž .termined by Addington et al. 1993 for the CDSS.Definition of that cut-off point enables confirma-tion of the reported relationships between de-pressive symptoms and certain aspects of thesymptoms of schizophrenia. Thus, when com-pared to non-depressed patients, depressedpatients have significantly higher scores for thepositive sub-scale and the general psy-chopathology sub-scale of the PANSS. These re-sults are in favour of a relationship between themood disorders and the positive symptoms ofschizophrenia as suggested by certain authorsŽDollfus et al., 1993; Sax et al., 1996; Addington

.et al., 1998 .In conclusion, the CDSS is a valid instrument

for evaluating depressive symptoms in schizo-Žphrenia. However, two items of the CDSS early

.awakening and guilty ideas of reference requirefurther discussion. It would be appropriate toconduct a confirmatory analysis in order to spec-ify the unidimensional character of the scale. Totest the unidimensional character, the Rash model

Ž .would be appropriate Nunnally, 1994 . Studiesshould be conducted to verify the psychometricproperties of the CDSS version containing onlyseven items. The CDSS enables simple character-isation of the depressed schizophrenic patientsand a cut-off point greater than six may be re-tained. The relationship between the depressivesymptoms and the other symptomatic dimensions

Ž .of schizophrenia particularly positive symptomsneeds to be elucidated as a function of diseaseprogression using the CDSS. The CDSS currentlyconstitutes the only depression scale that hasbeen validated in schizophrenic populations.

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evaluation of depression in schizophrenia: psychometric properties of a french version of the...

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