discuss the validity and reliability of diagnosis by mr daniel hansson

Discuss the validity and Discuss the validity and reliability of diagnosisreliability of diagnosis

By Mr Daniel HanssonBy Mr Daniel Hansson

The purpose of diagnosisThe purpose of diagnosis

To identify groups of similar sufferers so that To identify groups of similar sufferers so that psychiatrists and psychologists may develop psychiatrists and psychologists may develop explanations and methods to help those explanations and methods to help those groupsgroups

Billing purposes. The government and many Billing purposes. The government and many insurance companies require a diagnosis for insurance companies require a diagnosis for paymentpayment

Techniques of diagnosisTechniques of diagnosis

ObservationObservation InterviewInterview Psychological tests (e.g. IQ tests)Psychological tests (e.g. IQ tests) Brain scansBrain scans

DSM-IV-TRDSM-IV-TR

The classification system used in the United The classification system used in the United StatesStates

Lists more than 250 mental disordersLists more than 250 mental disorders The diagnosis of one individual is based on The diagnosis of one individual is based on

five dimensionsfive dimensions

The five dimensions of DSM-IV-TRThe five dimensions of DSM-IV-TR

Axis I:Axis I: The major diagnostic classification, e.g. major The major diagnostic classification, e.g. major depressive disorder, anorexiadepressive disorder, anorexia

Axis II:Axis II: Related to developmental and personality Related to developmental and personality disorders (e.g. autism, anti-social personality)disorders (e.g. autism, anti-social personality)

Axis III:Axis III: Physical and medical conditions that may worsen Physical and medical conditions that may worsen the disorder (e.g. brain injury, drug abuse, viruses)the disorder (e.g. brain injury, drug abuse, viruses)

Axis IV:Axis IV: Psychosocial stressors, all stressful events that Psychosocial stressors, all stressful events that may be relevant to the disorder (e.g. poverty, divorce, loss may be relevant to the disorder (e.g. poverty, divorce, loss of job)of job)

Axis V: Axis V: Global assessment of functioning. Rates the Global assessment of functioning. Rates the highest level of social, occupational and psychological highest level of social, occupational and psychological functioning on a scale of 1 (persistent danger) and 90 functioning on a scale of 1 (persistent danger) and 90 (good in all areas) currently and during the last year(good in all areas) currently and during the last year

Reliability and validity of diagnosisReliability and validity of diagnosis

Reliability of diagnosis:Reliability of diagnosis: Will different Will different diagnosticians using the same classification diagnosticians using the same classification system arrive at the same diagnosis?system arrive at the same diagnosis?

Validity of diagnosis: Validity of diagnosis: Does the person Does the person diagnosed have real symptoms with a real diagnosed have real symptoms with a real underlying cause? (underlying cause? (the illness is not socially the illness is not socially constructed, the person is not fakingconstructed, the person is not faking))

Reliability of diagnosisReliability of diagnosis

The reliability of earlier systems for The reliability of earlier systems for diagnosis, e.g. DSM-II, was very poor, but it diagnosis, e.g. DSM-II, was very poor, but it has been improved in revisions of the has been improved in revisions of the systems, e.g. DSM-IV-TRsystems, e.g. DSM-IV-TR


Beck (1962):Beck (1962): Agreement between two Agreement between two psychiatrists on diagnosis for 153 patients was 54 psychiatrists on diagnosis for 153 patients was 54 %. This was due to vague criteria for diagnosis %. This was due to vague criteria for diagnosis and different ways of psychiatrists to gather and different ways of psychiatrists to gather informationinformation

Cooper et. al. (1972): Cooper et. al. (1972): When shown the same When shown the same video clips, New York psychiatrists are twice as video clips, New York psychiatrists are twice as likely to diagnose schizophrenia than London likely to diagnose schizophrenia than London psychiatrists. London psychiatrists were twice as psychiatrists. London psychiatrists were twice as likely to diagnose mania or depression than New likely to diagnose mania or depression than New York psychiatristsYork psychiatrists


Di Nardo (1993): Di Nardo (1993): Two clinicians separately Two clinicians separately diagnosed 267 people seeking treatment for diagnosed 267 people seeking treatment for anxiety and stress disorders. They found anxiety and stress disorders. They found higher reliability for obsessive compulsive higher reliability for obsessive compulsive disorder but lower reliability for major disorder but lower reliability for major depressiondepression

Validity of diagnosisValidity of diagnosis There is a tendency of practitioners of overemphasizing dispositional rather There is a tendency of practitioners of overemphasizing dispositional rather

than situational causes of behaviour when diagnosing patients (than situational causes of behaviour when diagnosing patients (Fundamental Fundamental attribution errorattribution error))

The labelling of patients with certain disorders may affect the practioners The labelling of patients with certain disorders may affect the practioners perceptions of them (perceptions of them (compare with researcher biascompare with researcher bias), patients may act the label ), patients may act the label that has been given to them (that has been given to them (self fulfilling prophecyself fulfilling prophecy). The label itself may ). The label itself may simplify a problem that is highly complex simplify a problem that is highly complex

People may fake mental illness in order to avoid punishment People may fake mental illness in order to avoid punishment (The insanity (The insanity defense)defense)

Szaz 1967:Szaz 1967: Many disorders may be culturally constructed. If the biological Many disorders may be culturally constructed. If the biological causes of the mental disorder are known, the individual may be diagnosed with causes of the mental disorder are known, the individual may be diagnosed with mental disorder (mental disorder (the mental illness criterionthe mental illness criterion). If there is no biologically ). If there is no biologically underlying cause of the disorder, it is better to claim that the individual has underlying cause of the disorder, it is better to claim that the individual has problems with living or adaptingproblems with living or adapting

There are significant individual differences for mental disorders. An individual There are significant individual differences for mental disorders. An individual may have multiple mental disordersmay have multiple mental disorders

Validity of diagnosisValidity of diagnosis

Rosenhan (1973):Rosenhan (1973): 8 sane people could get 8 sane people could get admitted to mental hospitals merely by admitted to mental hospitals merely by claiming to hear voices.claiming to hear voices.

Rosenhan (1973): Rosenhan (1973): When a teaching When a teaching hospital was told to expect pseudo-patients, hospital was told to expect pseudo-patients, they suspected 41 out of 193 genuine they suspected 41 out of 193 genuine patients of being fakerspatients of being fakers


Temerline (1970):Temerline (1970): Clinically trained psychiatrists Clinically trained psychiatrists was influenced in their diagnosis by hearing the was influenced in their diagnosis by hearing the opinion of a respected authority. (opinion of a respected authority. (expert expert influenceinfluence). Participants watched a video-taped ). Participants watched a video-taped interview of a healthy individual. The authority interview of a healthy individual. The authority claimed, even though the person only seemed to claimed, even though the person only seemed to be neurotic (be neurotic (distress where behaviour is not distress where behaviour is not outside social norms, patient has not lost touch outside social norms, patient has not lost touch with realitywith reality) he was actually psychotic () he was actually psychotic (behaviour behaviour is outside social norms, loss of touch with realityis outside social norms, loss of touch with reality))


Chapman & Chapman (1967): Chapman & Chapman (1967): Beginning Beginning clinicians observed draw-a-person test drawing clinicians observed draw-a-person test drawing randomly paired (randomly paired (unknowingly to participantsunknowingly to participants) with ) with symptom statements of patients. Although the symptom statements of patients. Although the relationship between symptoms and drawings relationship between symptoms and drawings were absent, participants rated a high associative were absent, participants rated a high associative strength between symptom and drawing strength between symptom and drawing characteristics (characteristics (e.g. paranoia and drawing big e.g. paranoia and drawing big eyeseyes))


Lipton & Simon (1985):Lipton & Simon (1985): 131 patients were 131 patients were randomly chosen at a New York hospital. randomly chosen at a New York hospital. Initially there were 89 patients diagnosed Initially there were 89 patients diagnosed with schizophrenia, eventually only 16. with schizophrenia, eventually only 16. Initially, there were 15 diagnosed with Initially, there were 15 diagnosed with depression, eventually there were 50.depression, eventually there were 50.

EvaluationEvaluation

There is a large amount of research supporting the There is a large amount of research supporting the view that the reliability and validity of diagnosis are view that the reliability and validity of diagnosis are poor. This is due to many reasons, e.g. a possible poor. This is due to many reasons, e.g. a possible social construction of mental illness, poor social construction of mental illness, poor diagnostic tools, the possibility of faking, social diagnostic tools, the possibility of faking, social influence, errors in attribution by practitioners and influence, errors in attribution by practitioners and labelinglabeling

There are significant individual and cultural There are significant individual and cultural differences for the symptoms of mental disorders. differences for the symptoms of mental disorders. An individual may have multiple mental disordersAn individual may have multiple mental disorders

A wrong diagnosis may lead to a social stigma (an A wrong diagnosis may lead to a social stigma (an ethical issue)ethical issue)

Counter argumentCounter argument

There are methodological problems with the studies on There are methodological problems with the studies on validity and reliability (validity and reliability (researcher bias, generalisability, researcher bias, generalisability, ecological validityecological validity))

Revised diagnostic tools are higher in reliability than earlier Revised diagnostic tools are higher in reliability than earlier versions, e.g. DSM-IV-TRversions, e.g. DSM-IV-TR

Many people do seek help voluntarily for disorders (which Many people do seek help voluntarily for disorders (which may mean that the disorder is valid)may mean that the disorder is valid)

The reliability of diagnosis is high for some disorders, e.g. The reliability of diagnosis is high for some disorders, e.g. obsessive compulsive disorderobsessive compulsive disorder

There are many similarities of disorders across culturesThere are many similarities of disorders across cultures Diagnostic systems do not classify people, but the Diagnostic systems do not classify people, but the

disorders that they havedisorders that they have

discuss the validity and reliability of diagnosis by mr daniel hansson

Documents