Reliability and Validity of Diagnosis and Classification

Classification

ICD-10 and DSM-5 cluster symptoms together to identify disprders and distinguish them from each other

Diagnosis

Classification then used to identify disorders in individuals with specific symptoms

Reliability

extent to which 2 or more psychiatrists give the same diagnosis of 1 person (inter-rater) or 1 psychiatrist gives the same diagnosis for 1 person on 2 occasions (test-retest)

validity

extent to which a diagnosis/classification reflect reality. e.g, validity is low because ICD and DSM disagree.

low reliability due to..

• vague diagnostic criteria

• lack of precision / structure

• open to subjective judgement / interpretation

higher reliability due to

• clearer criteria and procedures

• more precision / structure to diagnosis e.g types/duration/severity of symptoms

low validity due to

• disagreement in diagnostic criteria

• gender bias

• cultural bias

co-morbidity

when two disorders frequently occur together, reduces validity of diagnosis. e.g schizophrenia and bipolar disorder

gender bias

when one gender is under-diagnosed and/or over-diagnosed.(women may he underdiagnosed in the uk)

culture bias

a psychiatrist from one culture may misdiagnose people from a different cultural background

symptom overlap

when disorders share the same symptoms, reduces validity because its hard to distinguish between the disorders.

symptoms which overlap in schizophrenia, unipolar and bipolar depression

low mood, sleep deprivation

what are the consequences of symptom overlap?

it can lead to inconsistencies with diagnosis, lack of reliability. patients may not receive the right treatment.

cotton et al 2009, gender bias

women are more likely to be under diagnosed because they have closer relationships and get support, meaning they function better than men. therefore they don't receive treatment which may benefit them.

pinto and jones, culture bias

british people of african-caribbean are up to 9 times as likely to receive a SZ diagnosis as white british people, although people living in african-caribbean countries aren't. ruling out genetic vulnerability.

escobar, culture bias (follow up)

over-interpretation of symptoms in black british people. black people are discriminated against by a culturally-biased diagnostic system