Public health significance of mixed anxiety and depression: beyond current classification

Transcription

1 The British Joural of Psychiatry (2008) 192, doi: /bjp.bp Public health sigificace of mixed axiety ad depressio: beyod curret classificatio Jayati Das-Mushi, David Goldberg, Paul E. Bebbigto, Diesh K. Bhugra, Traolach S. Brugha, Michael E. Dewey, Rachel Jekis, Rob Stewart ad Marti Price Backgroud The public health sigificace of mixed axiety depressive (MADD) ad the distictiveess of its pheomeology have yet to be established. Aims To determie the public health sigificace of MADD, ad to compare its pheomeology with ICD 10 axiety, depressive, ad comorbid axiety ad depressive s. Method Weighted aalysis of data from the Great Britai Natioal Psychiatric Morbidity survey was coducted with a represetative household sample of 8580 persos aged years. Results The 1-moth prevalece of MADD was 8.8%. A fifth of all days off work i Britai occurred i this group. The symptom profile of MADD was similar to pure ICD 10 axiety ad depressio, but with a lower overall symptom cout. The was associated with sigificat impairmet of health-related quality of life. Differeces i health-related quality of life measures betwee diagostic groups were accouted for by overall symptom severity, which remaied strogly associated with health-related quality of life measures after adjustig for diagostic group. The fidig that half of the axiety, depressio ad MADD cases ad a third of the comorbid depressio ad axiety cases grouped ito a sigle latet class challeges the otio of these coditios as havig distict pheomeologies. Mixed presetatios may be the orm i the populatio. Coclusios The data support the pathological sigificace of MADD i its egative impact upo populatio health. Dimesioal approaches to classificatio may provide a more parsimoious descriptio of axiety ad depressive s compared with categorical approaches. Declaratio of iterest Noe. Mixed axiety depressive (MADD) is a provisioal diagosis i ICD 10 ad DSM IV, 1,2 ad describes the presece of sub-threshold depressive ad axiety symptoms. 1 3 The otio that there might be a cliically relevat hiterlad of mixed beyod the specific axiety ad depressio diagoses is much older tha curret diagostic osology, 3 5 ad studies have reported groups of people with sigificat distress ad impairmet of fuctioig who do ot meet diagostic criteria for depressio or axiety. 3 Mixed axiety depressive remais subdefiitioal withi both ICD 10 ad DSM IV, 1,2 implyig a lesser status withi the diagostic hierarchy. However, there is little iformatio o the populatio-level impact of this, compared with pure or comorbid axiety ad depressive s. We therefore sought to ivestigate impairmet i a variety of idicators of health-related quality of life, comparig them betwee those with pure ICD 10 depressive, pure ICD 10 axiety, comorbid depressive ad axiety s, ad MADD, usig data from the Great Britai Natioal Psychiatric Morbidity survey of I additio, we sought to exted curret debates regardig categorical v. dimesioal approaches to the classificatio of the commo metal s. Comorbidity has bee argued to be a by-product of eforcig categorical costructs oto dimesios of symptoms. 7 9 There is evidece to support the otio that cases of psychiatric morbidity fall withi a sigle spectrum of couts of commo metal symptoms, with o evidece of idividual or specific clusterig of symptoms ito s as proposed by existig diagostic osologies. 10 Applyig this dimesioal model, MADD could be costrued simply as the lower ed of a cotiuum where (subsydromal) depressio ad axiety symptoms coexist, whereas comorbid axiety ad depressio might be at the higher ed of the cotiuum where diagosable depressio ad axiety might coexist. We therefore set out to test, first, whether there is a idepedet effect of specific diagostic categories (pure ad comorbid axiety ad depressive s, ad MADD) o health-related quality of life outcomes, after cotrollig for the effect of idividual symptom couts, ad, secod, whether there is ay evidece to support a distictive psychopathological pheomeology for MADD, compared with pure ad comorbid axiety ad depressive s. Method Settig The Natioal Psychiatric Morbidity survey was coducted i 2000, ad was the secod i a series of govermet-sposored surveys i Great Britai iteded to moitor the prevalece, impact ad treatmet of commo metal s, thereby iformig policy ad provisio. Major desig features are described here; full methodological details are available elsewhere. 6 Sample The study populatio comprised people aged years livig i private households i Eglad, Scotlad ad Wales. The primary samplig uits were 438 postcode sectors radomly selected from the Postcode Address File, stratified by regio ad socio-ecoomic group. 11 From each samplig uit, 36 addresses were selected at radom. Oe eligible perso was selected at radom per household, usig the Kish grid method

2 Das-Mushi et al Data collectio Traied o-cliical iterviewers carried out the iitial computerassisted structured iterviews. These were completed for 8580 persos, with a respose rate of 69.5%. The assessmet of sociodemographic characteristics, impairmet, use of services ad eurotic psychopathology was made i a sigle iterview of each participat, together with screeig for psychosis ad persoality s, i a subsequet iterview ot cosidered further here. Measures The Cliical Iterview Schedule Revised (CIS R) was used to assess for the presece of commo metal s. 13 The CIS R icludes 14 sectios coverig differet symptom clusters: somatic symptoms, fatigue, cocetratio, sleep, irritability, worries over physical health, depressio, depressive ideas, worry, axiety, phobias, paic, compulsios ad obsessios. Iitial filter questios i each sectio establish the existece of a particular symptom i the previous moth, leadig to a more detailed assessmet focusig o the past week. Symptom cluster sub-scale scores rage from 0 to 4, except for the depressive ideas cluster sub-scale which has a maximum score of 5. For each cluster cliically sigificat symptoms are cosidered to be preset if respodets score 2 or more o the relevat sub-scale. The 14 sub-scale scores are summed to create a overall CIS R psychological morbidity score. Some further questios are icluded to eable ICD 10 diagostic criteria to be applied usig computer algorithms. Usig this method, six ICD 10 diagostic categories were obtaied: obsessive compulsive, geeralised axiety, depressive episode, phobias, paic ad MADD. The last-amed was cosidered to be preset if the participat scored 12 or more o the CIS R overall psychological morbidity scale (cosidered as the optimal cut-off poit for defiitio of cliically relevat morbidity), 13 but did ot fulfil criteria for ay of the diagoses elicited through ICD 10 diagostic algorithms, as described above. Comorbidity was cosidered to be preset if a participat simultaeously met ICD 10 criteria for ay axiety ad a depressive episode. Alcohol use was assessed by meas of the Alcohol Use Disorders Idetificatio Test (AUDIT). 14 This test was developed by the World Health Orgaizatio i order to idetify people with hazardous or harmful patters of alcohol use. Scores greater tha 8 suggest problem drikig, with higher scores suggestive of harmful or hazardous alcohol use. For the purposes of this aalysis, AUDIT scores were broke dow ito three groups: 0 8, 8 15 ad Health-related quality of life was assessed usig six impact idicators coverig health, metal well-beig ad physical, social ad occupatioal fuctioig: (a) global health self-reported as poor ; (b) self-reported (lifetime) suicide attempt; (c) poor physical fuctioig (scorig i the lowest fifth of the 12-item Short Form Health Survey (SF 12) Physical Compoet score; 15 (d) impaired social ad occupatioal fuctioig, defied as a yes aswer to SF 12 item 6, Durig the past 4 weeks, have you accomplished less tha you would like with your work or other regular daily activities as a result of ay emotioal problems (such as feelig depressed or axious)? ; 15 (e) ot curretly employed (uemployed or ecoomically iactive); (f) 10 or more days off work i the previous year. I additio, the followig socio-demographic idicators were also recorded: age, geder, marital status ad occupatio. Statistical aalysis Statistical aalyses were coducted usig Stata versio 8.0 for Widows. Where possible, give the multistage stratified samplig desig, aalyses were weighted to take accout of differig selectio probabilities at each stage, ad of o-respose usig post-stratificatio. Estimates of prevalece ad associatio were made usig the appropriate Stata survey commads to geerate robust stadard errors. The prevalece of the six key impairmet idicators was estimated for those with MADD, pure depressive episode, pure axiety, ad comorbid ICD 10 axiety with depressive episode, ad for those with o metal. Odds ratios were estimated for the associatios betwee diagostic group ad impairmet idicator comparig MADD (the referece category) with pure ad comorbid ICD 10 axiety s ad depressive episodes. These crude estimates of associatio with health-related quality of life idicators were subsequetly adjusted usig the Stata weighted logistic regressio svylogit procedure for age ad geder, ad the for age, geder ad CIS R psychological morbidity score (etered ito the model as a cotiuously distributed variable estimatig chage i odds per uit icrease i CIS R score). Populatio attributable fractios for the associatios betwee, first, diagostic group (MADD, pure depressio, pure axiety, comorbid depressio ad axiety, o diagosis) ad secod, CIS R psychological morbidity score i fifths, ad each of the health-related quality of life idicators, were estimated usig the Stata commad aflogit from the prevalece ratios obtaied from uweighted Poisso regressio models cotrollig for age ad geder. To ivestigate the groupig of participats i a data-drive way we carried out a latet class aalysis. The R program ( was used with the package polca. The 14 symptom cluster sub-scales, dichotomised as scores of less tha 2 v. 2 or more, were used as the maifest variables. The optimal umber of classes was determied usig Akaike s iformatio criterio. We report, for each class, the predicted class membership ad the coditioal item (symptom cluster) respose probabilities. Results Prevalece ad socio-demographic correlates of commo metal s The weighted prevalece rates for commo metal s were depressive episode 2.6%, paic 0.7%, geeralised axiety 4.4%, obsessive compulsive 1.1% ad phobia 1.7%. O this basis participats could be divided ito three groups: depressive episode oly (mild, moderate or severe depressive episode), weighted prevalece 1.1% (¼101); axiety oly (geeralised axiety, paic, obsessive compulsive, phobia), 5.1% (¼485); ad comorbid depressive ad axiety s, 1.5% (¼154). A further 769 participats (weighted prevalece 8.8%) were categorised as havig MADD o the basis of a score greater tha 12 o the CIS R ad ot meetig ICD 10 diagostic criteria for ay of the coditios listed above. Thus MADD was the most prevalet, costitutig aroud half of all commo metal s. The remaiig 7071 participats (weighted prevalece 83.6%) were classified as o-cases havig o diagosable eurotic metal uder the study criteria. The demographic characteristics of these five groups are described i Table 1. Participats with comorbid ICD 10 depressio ad axiety were less likely to be married ad more likely to be of lower occupatioal status. 172

3 Mixed axiety ad depressive Table 1 Socio-demographic characteristics of sample by metal health status (weighted aalysis) No-case Depressio Axiety Comorbid depressio ad axiety Mixed axiety ad depressio Female, % Age, years: mea (s.d.) 42.8 (0.2) 40.7 (1.6) 42.7 (0.7) 43.2 (1.1) 40.9 (0.6) Married, % Low-skilled occupatio, % Symptomatology Examiatio of the distributio of total CIS R symptom scores (Fig. 1) idicates that those with comorbid ICD 10 axiety ad depressive s were most symptomatic, followed by those with ICD 10 depressive, the by those with ICD 10 axiety s, ad the by those with MADD. All four diagostic groups were markedly more symptomatic tha the o-cases group. The distributio of cliically sigificat symptoms (a score of 2 or more o each CIS R symptom subscale) was similar i those with pure ICD 10 depressive, pure axiety ad MADD (Fig. 2), other tha that those with depressive who were more likely to have symptoms of depressio ad depressive ideas, ad those with axiety who were more likely to have symptoms of axiety ad paic. Chi-squared tests performed for heterogeeity for each symptom (Fig. 2) by diagostic group were P i each case. Withi the group with a MADD diagosis, 8.7% had either specific symptoms of depressio (depressio or depressive ideas) or axiety (axiety, paic or phobias); 24.3% had specific depressio symptoms without specific axiety symptoms; 19.1% had specific axiety symptoms without depressio symptoms; ad 47.9% had both specific depressio ad axiety symptoms. No-specific symptoms predomiated, with 98.9% experiecig oe or more of somatic symptoms, fatigue, cocetratio problems, sleep problems, irritability or worry. each idicator, those categorised as o-cases were much less impaired tha ay of the four diagostic groups. This was ot the focus of this aalysis ad these results are ot preseted i more detail. Compared with participats with MADD, after adjustig for age ad geder, those with comorbid ICD 10 depressio ad axiety were more likely to report poor health, worse fuctioig, lifetime suicide attempts ad uemploymet. Those with axiety were also slightly more likely to report lifetime suicide attempts. No other group differece was foud. Adjustig for comorbid alcohol use usig the AUDIT did ot affect these fidigs. However, much if ot all of the effect of diagostic group upo health-related quality of life idicators was fully accouted for after cotrollig for total umber of symptoms (CIS R psychological morbidity score). It was clear from the same models that there was a idepedet statistically sigificat effect of umber of symptoms upo each of the healthrelated quality of life idicators after adjustig for diagostic group, age ad geder. The odds ratios per 1-poit icrease i CIS R score were as follows: for poor health OR¼1.12 (95% CI ); for suicide attempt OR¼1.10 (95% CI ); for the bottom fifth of the SF 12 Physical Compoet score OR¼1.12 (95% CI ); for health results i accomplishig less OR¼1.11 (95% CI ); for uemploymet OR¼1.05 (95% CI ); ad for days off work OR¼1.08 (95% CI ). We compared directly the overall effect first of diagostic group ad the of umber of symptoms upo each of Associatios with quality of life idicators Next we tested for associatios betwee the diagostic groups ad various idicators of health-related quality of life (Table 2). For Fig. 1 Box-plot distributio of Cliical Iterview Schedule Revised total symptom scores for the five diagostic groups (circles idicate outlier scores, more tha 1.5 box widths from the media). Fig. 2 Prevalece of cliically sigificat symptoms (two or more reported i each category) amog those with pure depressive episodes, pure axiety s, mixed axiety depressive, ad comorbid depressive episode ad axiety. 173

4 Das-Mushi et al Table 2 Associatio of commo metal diagoses ad health-related quality of life idicators (weighted aalysis) No-case Pure depressive episode Pure axiety Comorbid depressive episode ad axiety Mixed axiety depressive Poor health a b Lifetime suicide attempt SF 12 Physical Compoet score (bottom fifth) Health results i accomplishig less Uemployed/ecoomically iactive 10+ days of sickess absece i past year ( ) 0.6 ( ) ( ) 0.9 ( ) ( ) 0.5 ( ) ( ) 0.8 ( ) ( ) 1.0 ( ) ( ) 1.2 ( ) ( ) 0.5 ( ) ( )* 1.1 ( ) ( ) 0.6 ( ) ( ) 0.5 ( ) ( ) 1.1 ( ) ( ) 0.7 ( ) ( )* 0.7 ( ) ( )** 0.9 ( ) ( )* 0.5 ( ) ( )** 0.6 ( ) ( )** 2.0 ( )* ( ) 1.2 ( ) Ref., referece category; SF 12, 12-item Short Form Health Survey. a. adjusted for age ad geder. b. adjusted for age, geder ad Cliical Iterview Schedule Revised score. *P50.05, **P the health-related quality of life idicators usig populatio attributable fractios (Table 3). For each idicator the total populatio attributable fractio for umber of symptoms comfortably exceeded that for diagostic group. By weightig back to the base populatio, we were able to estimate the total days off work per aum cotributed i Great Britai by people i five mutually exclusive categories: those categorised as o-cases (i.e. o discerible commo metal ) ad those i the four metal health diagostic groups. The results were as follows: o-case group, millio days (95% CI ) (i.e. 59% of the total 204 millio days take off work per aum); pure ICD 10 depressio group, 7.2 millio days (95% CI ) (i.e. 4%); pure ICD 10 axiety group, 25.1 millio days (95% CI ) (i.e. 12%); comorbid ICD 10 depressio ad axiety group, 9.6 millio days (95% CI ) (i.e. 5%); MADD group, 41.4 millio days (95% CI ) (i.e. 20%). Table 3 Relative cotributios of commo metal s to health-related quality of life measures Pure depressio Pure axiety Populatio attributable prevalece fractio, % (95% CI) a Comorbid depressive episode ad axiety Mixed axiety depressive Total PAF for diagoses b Total PAF for symptoms c Poor health 2.0 ( ) 7.9 ( ) 5.2 ( ) 13.1 ( ) 28.3 ( ) 59.8 ( ) Lifetime suicide attempt 3.8 ( ) 15.3 ( ) 10.7 ( ) 17.8 ( ) 47.6 ( ) 78.0 ( ) SF 12 Physical Compoet score (bottom fifth) 0.8 ( ) 3.9 ( ) 2.3 ( ) 7.5 ( ) 14.5 ( ) 45.3 ( ) Health results i accomplishig less 2.3 ( ) 6.3 ( ) 4.7 ( ) 13.2 ( ) 26.5 ( ) 64.1 ( ) Uemployed/ecoomically iactive 0.5 ( ) 2.3 ( ) 1.8 ( ) 2.1 ( ) 6.7 ( ) 9.4 ( ) 10+ days of sickess absece i past year 2.6 ( ) 6.3 ( ) 11.1 ( ) 3.5 ( ) 23.5 ( ) 44.8 ( ) PAF, populatio attributable fractio; SF 12, 12-item Short Form Health Survey. a. Populatio attributable prevalece fractios adjusted for age ad geder. b. Pure depressio, pure axiety, comorbid depressive episode ad axiety, mixed axiety depressive. c. Total Cliical Iterview Schedule Revised psychological morbidity scores i fifths. 174

5 Mixed axiety ad depressive Fig. 3 Coditioal probability of cliically sigificat symptoms (two or more symptoms reported i each category) by latet class. Latet class aalysis Latet class aalysis (LCA) of the data revealed five classes (Table 4). Figure 3 displays how each of the four mai pathological classes (the fifth class, comprisig mostly o-cases is ot show) is associated with the reportig of cliically sigificat symptoms i each symptom cluster. The first class ( comorbid fear i Fig. 3) teded to represet cases previously diagosed as comorbid depressio ad axiety. The secod class ( distress ) icluded a sigificat proportio of all four of the origial diagostic categories ( pure depressio, pure axiety, comorbid depressio ad axiety, ad early half of all MADD cases). The third ( fatigued worry ) ad fourth ( fatigue ) classes were domiated by participats who had bee previously classified as o-cases, alogside a sigificat proportio of those previously diagosed with MADD (Table 4). The fifth class appeared to be mostly represeted by cases formerly withi the o-case group. Discussio Stregths ad weakesses This aalysis used data from a atioally represetative populatio survey with a large sample size. All participats were admiistered a structured cliical iterview, the CIS R, geeratig ICD 10 diagoses. Uusually, the CIS R icludes a comprehesive assessmet of axiety ad depressive symptoms regardless of whether the respodet meets criteria for a specific. It is therefore particularly well suited for exploratio of sub-threshold coditios such as MADD. The Natioal Psychiatric Morbidity survey also icorporated multiple idicators of impairmet coverig differet domais of health-related quality of life. There are, however, some limitatios. The CIS R is a fully structured assessmet admiistered by traied lay iterviewers, ad cocers have bee expressed regardig the validity of such measures, particularly at the level of idividual diagoses. 16,17 The MADD criterio developed by the Natioal Psychiatric Morbidity survey ivestigators has ot previously bee validated, ad did ot map precisely o to those proposed i ICD 10. I additio, the cross-sectioal desig ad reliace o self-reported outcomes make it difficult to exclude the possibility that iformatio bias could have led to a overestimatio of the associatio betwee commo metal s ad the various idices of impairmet i health-related quality of life. The high frequecy of o-respoders (31.5%) might have itroduced a variety of biases with respect to prevalece ad associatio with healthrelated quality of life idicators. The characteristics of orespoders are ukow. Should MADD be cosidered a sub-defiitioal? Our aalyses of data from the Natioal Psychiatric Morbidity survey suggest that MADD may accout for half of all cases of commo metal i Great Britai. The impact of MADD upo health-related quality of life is similar to that of pure axiety ad depressio, but somewhat less tha that of comorbid s. Twelve per cet of those with MADD reported a lifetime suicide attempt. Twety per cet of all disability days i Great Britai occurred i people with MADD, accoutig for aroud half of all the disability days occurrig i people with commo metal s. The results of this aalysis support the pathological sigificace of MADD, which does ot seem to be a sub-defiitioal at least i terms of its egative impact upo populatio health ad well-beig. This is a importat cosideratio. Critics have rightly queried the tedecy to exted the boudaries of what is cosidered metal, arguig that this ivolves the medicalisatio of ormal huma distress. However, our data suggest that may cases of MADD have merely slipped through the gaps i the curret classificatory system. Oce careful attetio had bee give to the diagostic criteria (see below), iclusio of MADD would seem to be amply justified as a ecessary correctio to omissios i the curret classificatio, rather tha a attempt to lower the threshold to iclude mior cases of dubious psychopathological sigificace. Implicatios for pheomeology ad classificatio That oe latet class icludes three-quarters of the pure depressio cases, half of the axiety cases ad a third of the comorbid depressio ad axiety cases challeges the otio of these coditios as havig distict pheomeologies, oce the complete Table 4 Latet class aalysis Latet class No-case Pure depressive episode Pure axiety Comorbid depressive episode ad axiety Mixed axiety depressive Class membership % Total

6 Das-Mushi et al profile of symptoms has bee take ito accout. Nearly half of MADD cases were also grouped i this geeral distress class. The symptom profile of MADD was similar i our survey to that of pure cases of ICD 10 axiety ad depressive episode, but with fewer specific axiety ad depressio symptoms, ad a lower overall symptom cout tha i cases of comorbid ICD 10 axiety ad depressive. Mixed presetatios may be the orm, at least i the geeral populatio. It would seem that desigatig cases as pure depressive episode or pure axiety is ofte a misomer symptoms i the other group are preset but isufficiet to support a diagosis i that category. These are certaily ot distict coditios; at the very least they should be cosidered to be closely related s with respect to pheomeology. That the other half of MADD cases were grouped ito latet classes domiated by o-cases (characterised by a high frequecy of symptoms of fatigue, sleep disturbace ad worry, but a low frequecy of core symptoms of depressio ad axiety) should raise some cocers regardig the cliical sigificace of the coditio, particularly as defied usig the Natioal Psychiatric Morbidity survey criterio. Cliical sigificace still eeds to be clarified, particularly with respect to exteral validators, atural history ad respose to psychological, social ad pharmacological itervetios. Neither progosis or aetiology could be studied i this aalysis of cross-sectioal survey data. It may be that this process will help us to defie the type, severity ad combiatio of symptoms that would merit a diagosis. Family history (ot addressed i this study) might also help to locate MADD with respect to related coditios. For example, a study by Reich suggests that axious persoality s may be icreased i relatives of people with comorbid axiety ad depressio compared with people with pure axiety s. 18 Criteria for research ad cliical practice Research ito MADD has bee hampered by the variety of defiitios i use. This may explai the widely varyig estimates of prevalece, as well as coflictig fidigs o the temporal stability of MADD compared with axiety or depressio The DSM IV MADD criterio seems to be too restrictive, 2 whereas that of ICD 10 is isufficietly operatioalised. 1 The criterio used i our aalysis simply required a score of 12 or more o the CIS R psychiatric morbidity scale (as well as the absece of a ICD 10 diagosis). As we have see, this did ot i practice guaratee the cocurrece of specific symptoms of depressio ad axiety; ideed, o-specific symptoms predomiated. This may have led to our fidigs overestimatig the prevalece of MADD, compared with more restrictive criteria such as those of DSM IV. The criterio for MADD used i this study was specific to the CIS R; evertheless, it did approximate to the defiitio of MADD as described i ICD 10. There are a wide variety of defiitios of MADD curretly i use; for example, Tyrer has proposed criteria for cothymia defied as the co-occurrece of axiety (geeralised or paic) ad depressive symptoms, with both axiety ad depressive symptoms ormally beig preset for at least part of the day, o every day, durig the last 4 weeks. 25 Although the operatioalised defiitio of MADD may be problematic, it seems clear that this should be oe area to be developed further i the forthcomig revisios of the two mai psychiatric classificatory systems (DSM IV ad ICD 10), ad further work is eeded o the diagostic validity of MADD. Dimesioal v. categorical models of commo metal We report o effect of diagostic group (icludig MADD) o most impact outcomes after adjustig for CIS R symptom score, but a large idepedet effect of CIS R symptom score o all impact measures after adjustig for diagosis (icludig MADD). To our kowledge, ours is the first report of its kid examiig directly the explaatory power of dimesioal v. categorical approaches. The superiority of the dimesioal perspective was illustrated both by the idepedet effect of the CIS R psychological morbidity score after adjustig for diagosis, ad by the much larger populatio attributable fractio across all healthrelated quality of life outcomes for fifths of the CIS R psychological morbidity score as compared with diagostic group. These fidigs further cofirm limitatios iheret withi purely categorical approaches to classificatio. 10,26,27 The validity of these categorisatios has bee questioed from a umber of differet perspectives, oe of which has bee the perceived dager of carvig ature at the joits. 28 I practice, however, both approaches have their place. Categorical approaches, based upo operatioally defied criteria, provide a essetial commo laguage, with demostrable reliability for cliical practice ad research. There is some evidece for the specificity of pharmacological ad psychological treatmets, ad fuctioal euroimagig ad euroedocriological evidece supports the otio of a distict eurobiology for major depressio ad geeralised axiety. Our fidigs strogly support the iclusio of a dimesioal perspective, without which the populatio burde of psychological morbidity is markedly uderestimated. Jayati Das-Mushi, MRCPsych, David Goldberg, MD, Istitute of Psychiatry, Kig s College Lodo; Paul E. Bebbigto, PhD, Departmet of Metal Health Scieces, Uiversity College Lodo; Diesh K. Bhugra, PhD, Istitute of Psychiatry, Kig s College Lodo; Traolach S. Brugha, MD, Departmet of Health Scieces, Uiversity of Leicester; Michael E. Dewey, PhD, Rachel Jekis, MD, Rob Stewart, MD, Marti Price, MD, Istitute of Psychiatry, Kig s College Lodo, UK Correspodece: Dr J. Das-Mushi, Sectio of Epidemiology, Istitute of Psychiatry, Kig s College Lodo, De Crespigy Park, Lodo SE5 8AF, UK. spsljdm@iop.kcl.ac.uk First received 7 Feb 2007, fial revisio 2 Oct 2007, accepted 15 Oct 2007 Ackowledgemets This work was developed, i part, to iform the America Psychiatric Istitute for Research ad Educatio s Task Force led review of the DSM IV classificatio. M.P. ad D.G. are members of the Depressio ad Geeralised Axiety Disorder Workig Group. No fudig was received. We are grateful to Has Ormel for helpful commets o a earlier draft of this paper. Refereces 1 World Health Orgaizatio. 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8 Public health sigificace of mixed axiety ad depressio: beyod curret classificatio Jayati Das-Mushi, David Goldberg, Paul E. Bebbigto, Diesh K. Bhugra, Traolach S. Brugha, Michael E. Dewey, Rachel Jekis, Rob Stewart ad Marti Price BJP 2008, 192: Access the most recet versio at DOI: /bjp.bp Refereces Reprits/ permissios You ca respod to this article at Dowloaded from This article cites 20 articles, 2 of which you ca access for free at: To obtai reprits or permissio to reproduce material from this paper, please write to permissios@rcpsych.ac.uk /letters/submit/bjprcpsych;192/3/171 o April 2, 2017 Published by The Royal College of Psychiatrists To subscribe to The British Joural of Psychiatry go to: