Mohammed T. Abou-Saleh

Principles and Practice of Geriatric Psychiatry.Editors: Professor John R. M. Copeland, Dr Mohammed T. Abou-Saleh and Professor Dan G. BlazerCopyright & 2002 John Wiley & Sons LtdPrint ISBN 0-471-98197-4 Online ISBN 0-470-84641-031Interviews Aimed at DifferentialPsychiatric DiagnosisGMS–HAS–AGECAT PackageJohn R. M. CopelandDepartment of Psychiatry, Royal Liverpool University Hospital, UKFor epidemiological and other studies of mental illness andmorbidity in older age it is important to ensure as far as possiblethat the differences in the levels of cases of illness found betweengeographical areas and between studies at different points intime are not due to methodological differences and, in particular,the way the diagnoses themselves are made. To overcome thisproblem, standardized interviews were introduced. The GMS–HAS–AGECAT Package consists of a series of interviewsdesigned to be given to a subject and his/her informant forassessing the dementias and depression, with optional sectionsfor minor mental illness 1,2 . The Geriatric Mental State (GMS)was derived originally from the Present State Examination 3 andthe Mental Status Schedule 4 . Substantial modifications andadditions were incorporated to make it more applicable toolder populations and to increase emphasis on organic states.The Package now provides, in addition to the GMS, which is aninterview with the subject, the History and Aetiology Schedule(HAS) for an informant, which allows the assessment of onsetand course of illness, past history, family history and certain riskfactors for dementia, depression and other mental illness. TheSecondary Dementia Schedule provides a semi-structured frameworkto aid in collecting information required for the NINCDS–ADRDA (National Institute of Neurology and CommunicativeDisorders and Stroke–Alzheimer’s Disease and Related DisordersAssociation) criteria 5 and the assessment of daily living.Standardization of diagnosis is achieved by the AGECAT(Automated Geriatric Examination for Computer AssistedTaxonomy) computer-assisted differential diagnosis 6–8 . Based onan extensive decision tree method, the system aggregates the datainto scores and allots each subject to levels of diagnosticconfidence on each of eight diagnostic syndrome clusters, organic,schizophrenia/paranoid, mania, depression (psychotic and neurotictype) (levels 0–5), obsessional, hypochondriacal, phobic andanxiety neurosis (levels 0–4). Levels 3 and above are what wouldusually be recognized by psychiatrists as cases of illness. Thecomputer then compares these levels with one another to derive afinal differential diagnosis and flags cases where the decision hasbeen difficult. The validity of the AGECAT diagnosis has beenassessed against psychiatrists’ diagnoses on the same patients. Therange of kappa values for the agreement between AGECAT andpsychiatrists’ diagnoses for organic states is 0.80–0.88 and fordepressive states 0.76–0.80 6 . Outcome studies are now providingadditional validation. After 3 years’ follow-up, over 83% ofAGECAT cases of organic disorder identified in a communitystudy were either dead or still dementing. One-third of depressedcases were also depressed 3 years later 9 . Post mortem validationstudies are in progress.In the second stage AGECAT uses the data from the HAS totake the diagnosis to a further stage, dividing organic states intoacute or chronic, and the latter into the different types of dementiausing a standardized form of the Hachinski score 10 . It alsoidentifies bereavements and flags coexistent immobility, pain, lifelongintellectual function and physical illness.The GMS can be used by trained lay workers and provides adiagnosis by AGECAT. When used in epidemiological studies it ispossible to derive prevalence figures for the full range ofpsychiatric morbidity using a one-stage design 11 . The measuresare therefore economical as well as reliable and valid. ThePackage does not rely on special psychological tests as these arenot applicable across cultures or socioeconomic groups or withpopulations of varying literacy. The interviews have also beentransferred for presentation on laptop computer, which improvesaccuracy and communication, avoids delays and costs in inputtingdata, and provides rapid access to results and easy quality controlof interviewing techniques 12 .These measures have been used in a number of projects, includingthe Medical Research Council (UK) ALPHA 13,14 study of theincidence of the dementias and the multicentre Cognitive Functionand Ageing Study, the EURODEP EC-funded Concerted Action 16 ,the ongoing ASIADEP studies in 12 Asian centres and the 10/66Club studies on the prevalence of dementia in India, Latin Americaand Africa, as well as forming part of the minimum data setrequired by the EURODEM (EC Concerted Action on Epidemiologyand Prevention of Dementia) 17,18 . The GMS has been translatedand used in a wide range of languages. Recently, algorithms havebeen developed for ICD-10, DSM-III-R and DSM-IV andcompared favourably with psychiatrists’ diagnoses using theseinternational criteria. The HAS has been shortened and modifiedto provide for the criteria of Lewy body dementia and otherrecognized dementia classifications.REFERENCES1. Copeland JRM, Kelleher MJ, Kellett JM et al. A semi-structuredclinical interview for the assessment of diagnosis and mental state inPrinciples and Practice of Geriatric Psychiatry, 2nd edn. Edited by J. R. M. Copeland, M. T. Abou-Saleh and D. G. Blazer&2002 John Wiley & Sons, Ltd