Issues in diagnosis and classification Flashcards
evaluation points for issues in diagnosis and classification
good reliability
low validity
co-morbidity
gender bias in diagnosis
culture bias in diagnosis
symptom overlap
good reliability - strength
Reliability means consistency. A psychiatric diagnosis is said to be reliable when different diagnosing clinicians reach same diagnosis for the same individual (inter-rater reliability) and when the same clinician reaches same diagnosis for same individual on two occasions (test-retest reliability). Prior to DMS-5 reliability was low, this has now improved. Osorio et al (2019) report excellent reliability for diagnosis of SZ in 180 individuals using the DSM-5. Pairs of interviewers achieved inter-rater reliability of +.97 and test-retest reliability of +.92. Therefore we can be reasonably sure the diagnosis of SZ is consistently applied.
low validity - weakness
Validity concerns whether we assess what we are trying to assess. One way to assess validity of psychiatric diagnosis is criterion validity. Cheniaux et al (2009) had two psychiatrists independently assess the same 100 clients using ICD-10 and DSM-IV criteria. Found that 68 were diagnosed with SZ under ICD system and 39 under DSM. This suggests SZ is either over or under diagnosed according to the diagnostic system. This suggests that criterion validity is low. However, in the Osorio et al study there was excellent agreement when they both used DSM system to diagnose SZ. This means the criterion validity for SZ is good provided it takes place within a single diagnostic system.
Rosenhan (1973). 8 sane people could get admitted to mental hospital merely by claiming to hear voices.
co-morbidity - weakness
If conditions occur together a lot of the time, it calls into question the validity of their diagnosis and classification because they might actually be a single condition. SZ is commonly diagnosed with other conditions. For example, one review found about half of those diagnosed with SZ also had a diagnosis of depression or substance abuse. This is an issue for classification as it means SZ may not exist as a distinct condition, and is an issue for diagnosis as at least some people diagnosed with SZ may actually have unusual cases of conditions like depression.
gender bias in diagnosis - weakness
Since the 1980’s men have been diagnosed with SZ more commonly than women (ratio of 1.4:1). One possible explanation is that women are less vulnerable than men, perhaps due to genetic factors. However, it seems more likely that women are underdiagnosed because they have closer relationships and hence get support (Cotton et al 2009). This leads to women with SZ often functioning better than men. This underdiagnosis is gender bias and means that many women with SZ may not be receiving treatment and services that will benefit them.
culture bias in diagnosis - weakness
Some symptoms of SZ, particularly hearing voices, have different meanings in different cultures. For example, in Haiti some people believe hearing voices are communications from ancestors. British people of African-Carribean origin are nine times as likely to receive a diagnosis as white British people. Although people living in African-Carribean countries are not. The most likely explanation for this is culture bias in diagnosis of clients by psychiatrists from a different cultural background. This means British African-Caribbean people may be discriminated against by a culturally-biased diagnostic system.
symptom overlap - weakness
There is considerable overlap between the symptoms of SZ and symptoms of other conditions. For example, both SZ and bipolar disorder involve positive symptoms (delusions) and negative symptoms (avolition). In terms of classification, this may suggest SZ and bipolar disorder may actually be variations of a single condition. In terms of diagnosis it means SZ is hard to distinguish from bipolar disorder. As with co-morbidity, symptom overlap means that SZ may not exist as a distinct condition and that even if it does, it is hard to diagnose. So both its classification and diagnosis are flawed.
