International Journal of Methods in Psychiatric Research, Volume 7, Number 2

The International Classification of Diseases (ICD) andthe Diagnostic and Statistical Manual of MentalDisorders (DSM) set out specific diagnostic criteriathat describe the essential characteristics of each disor-der. In their current forms, the ICD-10 (WHO, 1993)and the DSM-IV (APA, 1994a) appear to be compara-ble and much work has been done to reduce the differ-ences (Frances et al., 1991). A recent internationalversion of the DSM-IV has emerged that sets out theDSM-IV criteria, labelled by the ICD-10 codes (APA,1995), as though the two classifications were equiva-lent. However, cross-system diagnostic concordancecan only be ascertained by empirical analysis of casesassessed on both sets of criteria.

A substantial amount of research has accumulatedregarding cross-system diagnostic concordance in thesubstance use disorders (Grant, 1996; Hasin, Li,Mcloud and Endicott, 1996; Hasin, McCloud, Li.,Endicott, 1996; Langenbucher, Morganstern, Labourieand Nathan, 1994; Rapaport, Tipp and Schuckit,1993) and differences between various versions of theICD and the DSM have been found at the diagnosticlevel. Andrews and Slade (1998a, 1998b) and Peters,Slade and Andrews (1998) confirmed that there were

also marked discrepancies between the ICD-10 and theDSM-IV diagnoses in panic and agoraphobia, general-ized anxiety disorder, social phobia and post traumaticstress disorder, but not in obsessive-compulsive disor-der. The present paper extends that work to depressivedisorders, dysthymic disorder and the substance usedisorders.

In comparison with the anxiety disorders, differ-ences between the ICD-10 and the DSM-IV diagnos-tic criteria for the affective/mood disorders appear lesssignificant. In a study of diagnostic concordancebetween ICD-10 and DSM-III-R, Wacker, Mullejans,Klein and Battegay (1992) found that the majority ofdifferences in depressive episode were accounted for bythe lower threshold in the number of symptomsrequired by the ICD-10. Although small differencesexist in the definition of depression and of dysthymicdisorder between the ICD-10 and the DSM-IV, thediagnostic systems are largely comparable (Lopez Ibor etal., 1994). The differences that do exist probably relatemainly to subtle differences in the nature and numberof depressive symptoms necessary for a diagnosis.

The relationship between the diagnostic categoriesof substance dependence and substance abuse have

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Depression, dysthymia and substanceuse disorders: sources of dissonance betweenICD-10 and DSM-IV

GAVIN ANDREWS, TIM SLADE, School of Psychiatry, University of New South Wales at St Vincent’sHospital, Australia

ABSTRACT The present study examined the diagnostic concordance between ICD-10 and DSM-IV in the depressivedisorders, dysthymic disorder and substance dependence and substance harmful use/abuse disorder. The CompositeInternational Diagnostic Interview (CIDI) was administered to 1504 people, in a sample derived from community and clin-ic cases, and discrepant diagnoses were identified for ICD-10 and DSM-IV. The diagnostic concordance for the depressivedisorders, dysthymic disorder and substance dependence disorder was excellent (kappa = 0.89, 0.93, and 0.86, respec-tively). Diagnostic agreement in the substance harmful use/abuse disorder category was considerably lower (Kappa =0.44). The small number of discrepancies in diagnoses of the depressive disorders, dysthymic disorder and substance depen-dence disorder are a reflection of minor but real differences in the diagnostic criteria. Discrepancies in the diagnosis of sub-stance harmful use/abuse disorder are explained by different concepts proposed to define each disorder.

Key words: ICD-10, DSM-IV, depression, dysthymia, substance use, diagnostic concordance

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changed markedly with the introduction of DSM-IV(APA, 1994b). Substance abuse is no longer consid-ered a residual of substance dependence and containsits own diagnostic criteria. One result is that the con-cept of ‘abuse’ in DSM-IV and its equivalent, ‘harm-ful use’, in ICD-10 are quite different. In DSM-IV anabuse diagnosis is based on the occurrence of sub-stance-related adverse social consequences while inICD-10 harmful use is reflected by substance-relatedphysical or psychological harm. The diagnoses of sub-stance dependence in DSM-IV and ICD-10, on theother hand, differ only in minor respects, with ICD-10 including one criterion not found in DSM-IV andfour DSM-IV criteria combined into two ICD-10 criteria.

The aims of the present study are to use CompositeInternational Diagnostic Interview data from an anxi-ety disorders clinic and from an enriched communitysample to determine discrepancies in the depressivedisorders, dysthymic disorder and the substance usedisorders at the diagnostic and criterion levels, and torelate the discrepancies to key diagnostic constructs.

MethodThe sample comprised 1364 community volunteersand 140 people attending a specialized anxiety disor-ders clinic. The community volunteers came from arandom sample of 15 000 that were initially inter-viewed using a screener for mental disorders (Mroczekand Kessler, 1994). Subjects were selected for a fullinterview on the basis that all screener-defined ‘cases’and some non-cases would be invited to participate ina longitudinal health survey. The age and sex distribu-tion of cases detected in the community was 46 years,71% female, and in the clinic 31 years, 57% female.This reflects the age and sex distributions in the twoparent populations. These samples were combined toensure sufficient cases for identification of discrepantdiagnoses. Both samples may be biased – the commu-nity sample by including minor cases that cliniciansmight regard as sub-threshold, and the clinic sample byincluding too many severe cases – but the pattern ofdiscrepancies was examined and the issues upon whichwe comment, were evident in both samples.

Community subjects were interviewed by lay inter-viewers using the computerized version of the CIDI 2.0(CIDI-Auto; WHO, 1997). The lay interviewers weretrained to criterion and the computerized nature of theinstrument ensured that protocols were followed exact-ly. The clinic sample used exactly the same instrument

in the self-administered form. Peters, Clarke and Carroll(in press) have demonstrated little disagreementbetween the self-administered and the interviewer-administered CIDI. The CIDI includes questions tooperationalize each ICD-10 and DSM-IV diagnosticcriterion and so produces diagnoses according to each classification (Andrews and Peters, 1998).Combining the samples resulted in prevalences thatare different from the expected population preva-lences. However, the issue in this paper is the rela-tionship between the classifications, not the absoluteprevalences.

Exclusion criteria due to other mental disorderswere ignored because they differentially affect eachdiagnosis, and reflect issues of comorbidity, rather thaninform about the diagnostic criteria, per se. ICD-10depressive episode was compared to DSM-IV majordepressive disorder as both rule out the presence ofmania or hypomania, whereas major depressive episodein DSM-IV does not assess for the presence of mania orhypomania. The diagnostic criteria for ICD-10 andDSM-IV are described in detail in the respective man-uals. The ICD-10 and DSM-IV diagnoses of single andrecurrent, mild through severe, depressive episode(F3X.X) with single and recurrent, mild throughsevere, major depressive disorder (296.XX), dysthymia(F34.1) with dysthymic disorder (300.4), substancedependence disorders (F1X.2 with 304.X0) and sub-stance harmful use disorder (F1X.1) with substanceabuse disorder (305.X0) were compared, and 2 × 2tables constructed. When cases were negative on onediagnostic system and positive on the other, the specif-ic criteria that resulted in the discrepancies were iden-tified.

ResultsICD-10 F3X.X depressive episode and DSM-IV 296.XXmajor depressive disorder In the enriched sample the prevalences were 16.6%and 15.6% for ICD-10 and DSM-IV respectively. Two-hundred-and-sixty-five people in a 12-month periodmet criteria on one or both the classifications and 220(83%) met criteria on both (Kappa = 0.89, Yules Y =0.92) – see Table 1. Given data such as these, aresearch study of positive ICD-10 cases would include12% that did not meet criteria for DSM-IV, and posi-tive DSM-IV cases would include 6% that did notmeet criteria for ICD-10. There would be minimalproblems encountered if research in different countrieswas to be compared. The majority of discrepancies

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when either the ICD-10 is positive and the DSM-IV isnegative or vice versa relate to the respective symptomthresholds for each system. Thirty people were positiveon ICD-10 and negative on DSM-IV, 26 because theydid not have enough symptoms to meet the minimumDSM-IV criterion of five symptoms. The remainingfour are idiosyncratic and probably reflect random dif-ferences. Fifteen people were positive on DSM-IV andnegative on ICD-10, 11 because they have one symp-tom, either depression or loss of interest, but do notlack energy (the ICD-10 requires two symptoms fromdepression, loss of interest, or lack of energy).

ICD-10 F34.1 dysthymia and DSM-IV 300.4 dysthymicdisorder In this enriched sample the prevalences were 3.4% and3.1% for the ICD-10 and the DSM-IV respectively,again consistent with good agreement between theclassifications. Fifty-two people met criteria for dys-thymia on one or both the classifications and 45 (87%)met the criteria on both (kappa = 0.93, Yules Y = 0.98)– see Table 1. Given these rates of diagnostic concor-dance, a research study of positive ICD-10 cases would

include 12% that did not meet criteria for the DSM-IV, and positive DSM-IV cases would include 2% thatwere negative on ICD-10. As with the depressive dis-orders this would pose few problems if research in dif-ferent countries was to be compared. Six positive ICD-10 cases were negative on the DSM-IV, four becausethey did not meet criterion H (the symptoms causeclinically significant distress or impairment).

ICD-10 F1X.2 and 304.X0 substance dependence disorderThe prevalences in the enriched sample were 7.6% and8.5% for ICD-10 and DSM-IV respectively, consistentwith agreement between classifications. One-hundred-and-thirty-seven people met criteria for substance-dependence disorder on one or both the classificationsand 106 (77%) met criteria on both (Kappa = 0.86,Yules Y = 0.93) – see Table 1. With diagnostic concor-dance rates such as these, a study of positive ICD-10cases would include 8% that did not meet criteria forDSM-IV, and positive DSM-IV cases would include17% that were negative on ICD-10. Nine people werepositive on ICD-10 and negative on DSM-IV. Allthese people met exactly three criteria, one of which

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Table 1: Cross-classification of the depression, dysthymia, substance dependence and substance abuse/harmful use diagnosesdetermined by ICD-10 and DSM-IV

DSM-IV 296.XX depressive disorderNegative Positive Total

ICD-10 F3X.X Negative 1239 15 1254Depressive episode Positive 30 220 250 (16.6%)

Total 1269 235 (15.6%) 1504

DSM-IV 300.4 Dysthymic disorderNegative Positive Total

ICD-10 F34.1 Negative 1452 1 1453Dysthymia Positive 6 45 51 (3.4%)

Total 1458 46 (3.1%) 1504

DSM-IV 304.X0 Substance dependence disorderNegative Positive Total

ICD-10 F1X.2 Negative 1367 22 1389Substance dependence disorder Positive 9 106 115 (7.6%)

Total 1376 128 (8.5%) 1504

DSM-IV 305.X0 Substance abuse disorderNegative Positive Total

ICD-10 F1X.1 Negative 1311 67 1378Substance harmful Use disorder Positive 63 63 126 (8.4%)

Total 1374 130 (8.6%) 1504

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was ICD-10 criterion A part 1. As this criterion is notincluded in DSM-IV they failed to satisfy criteria forDSM-IV. Twenty-two people were positive on DSM-IV and negative on ICD-10. Again, all these peoplemet exactly three criteria, one of which was theimpaired capacity to control substance-taking behav-iour, which is split into two criteria in DSM-IV butremains one criterion in ICD-10.

ICD-10 F1X.1 substance harmful use disorder andDSM-IV 305.X0 substance abuse disorderThe prevalences in the enriched sample were almostidentical at 8.4% and 8.6% for ICD-10 and DSM-IVrespectively. One-hundred-and-ninety-three peoplemet criteria for substance harmful use/abuse on one orboth the classifications, yet only 63 (33%) met criteriaon both (Kappa = 0.44, Yules Y = 0.63). A study ofpositive ICD-10 substance harmful use disorder caseswould include 50% that did not meet ICD-10 criteria,and positive DSM-IV substance abuse disorder caseswould include 52% that were negative on ICD-10.Sixty-three people were positive on ICD-10 and nega-tive on DSM-IV. All of these people met the one ICD-10 requirement – that the substance use leads to phys-ical and/or psychological harm – yet they did not meetany of the four DSM-IV criteria. An almost equalnumber of people, 67, were positive on DSM-IV andnegative on ICD-10. All of these people met one of thefour essential DSM-IV criteria, yet did not meet theone ICD-10 criterion.

DiscussionDiscrepancies between the ICD-10 and the DSM-IVin diagnoses of the depressive disorders, dysthymic dis-order, and substance dependence and substance harm-ful use/abuse disorders were examined in the currentstudy. The chance-corrected agreements betweenthese ICD-10 and DSM-IV diagnoses range from fairfor substance harmful use/abuse disorder to excellentfor dysthymic disorder. However, when base rates arelow, kappa is not informative. Yules Y values of 0.93(substance dependence disorder), 0.94 (depressive dis-orders), and 0.98 (dysthymic disorder) indicate goodagreement even though the agreement in substanceharmful use/abuse disorder was understandably lower(Yules Y = 0.63).

There was good agreement in the depressive disor-ders and dysthymic disorder. The thresholds in thenumber of symptoms required to meet criteria differbetween the two classifications with ICD-10 requiring

four symptoms and DSM-IV requiring five. However,ICD-10 requires two of three key symptoms; depres-sion, loss of interest or lack of energy, and to someextent this may redress the apparent threshold differ-ence. It is interesting to note that symptom-related cri-teria have not been responsible for significant numbersof the ICD-10/DSM-IV discrepant diagnoses in theanxiety disorders (Andrews and Slade, 1998a, 1998b;Peters, Slade and Andrews, 1998) even though differ-ences in the nature and number of symptoms do exist,yet they appear to be the most important factor in theaffective/mood disorders.

The agreement between ICD-10 and DSM-IV in thesubstance use disorders was variable. Substance depen-dence diagnoses were highly concordant and discrepantdiagnoses were explained entirely by the configurationof symptoms in the respective nosological systems. Thisis a real yet minor difference between the systems that isnot likely to greatly influence comparisons of prevalencerates between systems. The diagnostic concordance forsubstance harmful use/abuse disorder is considerably lessthan ideal and is due to the complete lack of overlapbetween the ICD-10 and DSM-IV criteria for substanceharmful use and substance abuse diagnoses.

In summary, the agreement between the classifica-tions of depressive disorder, dysthymic disorder andsubstance dependence disorder is excellent, the resid-ual differences reflecting the detail in the constructionof the criteria. The situation with substance harmfuluse/abuse disorder is very different and, although con-sistent with past research (Grant, 1996; Hasin, Li,McCloud and Endicott, 1994; Hasin, McCloud, Li andEndicott, 1994; Langenbucher et al., 1994), the disso-nance reflects differing concepts of harmful use and ofabuse in each classification.

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Correspondence to: Gavin Andrews, Clinical ResearchUnit for Anxiety Disorders, 299 Forbes St, DarlinghurstNSW 2010, Australia. Telephone: +61 2 9332 1013.Fax: +61 2 9332 4316. E-mail: gavina@crufad.unsw.edu.au

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