Classification Systems: Validity

Concurrent Validity

A diagnosis can be said to be valid if two diagnostic systems agree about the symptoms of that mental health disorder.

E.g. A diagnosis of OCD would be valid if the symptom of repetitive behaviour is listed in both the DSM and ICD

Predictive Validity

If a diagnosis leads to a treatment and can be used to predict how that treatment will work on the patient, it has predictive validity.

E.g. a patient with depression prescribed antidepressants should get better if the diagnosis has predictive validity

Aetiological Validity

A valid diagnostic tool should also be able to identify the causes of a mental health disorder.

E.g. when using diagnostic tool on someone diagnosed with schizophrenia, we would expect to see overactivity in the dopamine pathway causing the disorder.

Operationalise the symptoms

A valid diagnostic system will operationalise the symptoms and behaviours that make up mental health disorders so they can be objectively measured.

E.g. auditory hallucinations must be upsetting and be present for at least 2 months.

Classification systems: Valid (1)

I: There is evidence that suggests that diagnosis based on classification systems are accurate

J: Kim-Cohen (2005) demonstrated the concurrent validity of diagnosing Conduct Disorder (CD) by using the DSM IV and interviewing the children, observing behaviours and using teacher questionnaires.

E: This is useful evidence as if multiple sources agree with a diagnosis it is more likely to be accurate

J: This study also suggests aetiological validity as specific risk factors for CD were identified e.g. low income makes with oarents with psychological disorders a

Classification systems: Invalid (2)

I: There is evidence to suggest a low concurrent validity for DSM and ICD.

J: Andrews et al (1999) found only a 68% agreement between the ICD-10 and DSM-IV on an assessment of 1500 patients

E: Therefore the diagnosis of the same mental health disorder could be incorrect when using different classification systems leading to incorrect treatments

Classification systems: Valid (2)

I: there is also evidence to suggest that the accurate diagnosis obtained using the ICD and DSM have predictive validity

J: Mason (1997) has shown that the diagnosis of schizophrenia using the ICD showed good predictive validity of future prognosis, involving flat affect and disorganised behaviour.

E: this is useful as it allows long-term treatment and support to be planned in order to enable individuals to manage disorder over time.

Classification systems: Invalid (2)

I: the findings from classic studies such as Rosenhan 1973 demonstrate that diagnosis can lack validity.

J: Rosenhan provided evidence that diagnosis were flawed as staff and psychiatrists were unable to tell the mentally ill from the stable.

E: This lowers the validity of diagnostic tools, accurately diagnosing schizophrenia. However, this study demonstrates the reliability of diagnosis as most of the pseudo patients (who displayed the same symptoms) were diagnosed with schizophrenia.