Diagnosing mental disorder is different as can't be seen or measured in a biological sense as cancer cells can be seen dividing. This makes diagnosis of mental disorders by the psychiatrists to be subjective.
RELIABILITY How CONSISTENT something is
In schizophrenia to see if diagnosis is consistent or not. Can refer to consistency over time like will same doc make same diagnosis second time with same symptoms and consistency btw docs.
Factors in reliability
KLIETMANN identified 3 factors which makes diagnosis of schizophrenia UNRELIABLE
DIFFERENCE BTW CLINICIANS
info interpreted differently by diff docs
Diff docs see symptoms in diff ways if they come from diff cultures
Cause disagreement in diagnosis LOWERS RELIABILITY in diagnosis
DIFFERENCE BTW PATIENTS
No two cases of schizophrenia are the same
Psychiatrist may misinterpret behaviour of a patient from diff culture to themselves and give a diff diagnosis than to a psychiatrist who is of the same culture
Further prob, symptoms that displayed or patient admits to on the day may be clear signs to schizo diagnosis, but may show one day and not another. So diff diagnosis another day.
DIFFERENCE IN CLASSIFICATION SYSTEMS
DSM IV TR (USA) The ICD 10 (Europe) CCMD 3 (China)
Problem is not all list same metal illness let alone CC. Like ICD 10 shows an extra 2 subtypes of schizophrenia. LOWERS RELIABILITY in diagnosis as diff docs use diff systems so diff diagnosis.
Research in Reliability FOR
JONES AND GRAY
Researchers looked at prevalence rates of schizophrenia by ethnicity. Afro Caribbean's. It was found that a large amount of Afro Caribbean's were diagnosed with schizo. This shows that reliability can be lowered due to cultural differences. Docs from diff cultures will interpret behaviour differently. Such as visits from spirits is norm but seen as hallucinations to some.
STEPHENS ET AL
Gave docs files of 283 patients hadn't met them in person, asked them to diagnose using 9 diff classification systems. Found out that different classification system led to diff diagnoses. Shows that reliability can be lowered by using different classification systems as they each have a different criteria to one another.
MOJTABI AND NICHOLSON
Gave 50 psychiatrists examples of delusions which they had to sort out as bizarre or non bizarre. Was found that they only agreed 40% of the time. Shows that even when using same classification verbal descriptions are interpreted differently so psychiatrists have own their own subjective interpretation. Which supports the idea that subjectivity lowers reliability.
COPELAND ET AL
Gave description of A patient to 134 US and 194 UK psychiatrist. 69% of US but 2% UK psychiatrists diagnosed the patient with schizophrenia. Supports the idea that culture of the psychiatrist can be a factor in lowering reliability of diagnosis.
Research in Reliability They are reliable
HARVEY ET AL
Carried out a meta analysis on all research carried out to test reliability of diagnosis of schizo. Found that older classification systems led to low reliability in diagnosis however more recent classification systems led to high reliability. Tells us that mental health community are making progress and modifying the systems to allow less subjectivity so more reliable diagnosis. So reliability of diagnosis is improving as classification systems are being revised.
PAGSBERG ET AL
Looked at the impact of the DSM V would have. Saw that the clinical characteristics were less vague and 2% that wee currently diagnosed will no longer be diagnosed. Overall he argues that DSM V will lead to much more reliable diagnosis of schizo and reliability will continue to be improved as classification systems are revised.