Reliability and Validity in Diagnosis and Classification of Schizophrenia Flashcards
A01 - What is reliability?
Good reliability means that the diagnosis of SZ is:
-Consistent between different diagnostic tools: DSM and ICD
-Consistent between different psychiatrists
-Consistent across culture, races and genders
- Consistent over time if the symptoms stay the same
A01 - What is validility?
Good validity means that the diagnostic system assesses what it claims to be assessing.
- In the case of schizophrenia, it means that patients who are diagnosed as suffering from
schizophrenia actually have that mental disorder.
The 2 main ways we assess validity are:
Construct validity – Do the symptoms displayed by the patient match the
characteristics listed in the DSM/ICD.
Criterion validity - criterion validity would be good if a patient received the same
diagnosis using a number of different diagnostic tools such as the DSM and ICD.
If validity is poor, diagnosis will be inaccurate, the prognosis will be inaccurate and choice of treatment e.g., drug therapy will be incorrect.
A01 - What is culture bias?
The validity of diagnosing and/or classifying schizophrenia may suffer from poor validity due
to a cultural bias. E.g., African Americans are three times more likely than white people to be
diagnosed with schizophrenia.
A01 - What is gender bias
- There are differences in the way in which men and women are diagnosed and experience schizophrenia, for instance, the onset of schizophrenia is usually earlier for men than women, women seem to show better social and cognitive functioning.
- Likewise, Goldstein found that men are readmitted to hospital twice as often for schizophrenia and stay in hospital twice as long as women, over a ten-year period.
-This may be because men are more genetically vulnerable to developing schizophrenia than
women. - It could also be that rather than diagnosing a person due to their symptoms, the gender of the patient may reduce the accuracy of judgement.
A03 - Gender bias
-One possible factor influencing gender bias may be that female patients typically function better than men, being more likely to work and have good family relationships.
- The better interpersonal functioning of females may bias practitioners to under-diagnose schizophrenia.
-Loring and Powell (1988) asked 290 male and female psychiatrists to read two case stories of patients’ behaviour and then make a diagnosis using standard diagnostic criteria.
-When the patients were described as ‘males’ 56% of the psychiatrists gave a diagnosis of schizophrenia. However, when the patients were described as ‘female’, only 20% were given a diagnosis of schizophrenia.
- Interestingly, this gender bias was not as evident among the
female psychiatrists, suggesting that diagnosis is influenced not only by the gender of the patient but also the gender of the clinician.
A03 - Culture bias
- Positive symptoms such as hearing voices may be more acceptable in African cultures because of cultural beliefs in communication with ancestors and spiritualism.
-Because of this, people from African cultures may be readier to acknowledge such experiences that are interpreted as schizophrenic symptoms, whereas White Western people may be more embarrassed and keep it to themselves.
-African Americans may have developed paranoid-like behaviours due to historical and contemporary experiences of racism and oppression.
-This, maybe an adaptive, healthy response to a racist society that has been misinterpreted as the schizophrenic symptom of paranoia.
A03 - What is co-morbidity?
- Comorbidity is where patients suffer from two or more mental disorders at the same time.
- This provides the diagnosis of schizophrenia with a problem. The symptoms of two disorders, and the negative symptoms of schizophrenia may then overlap making an accurate diagnosis very difficult.
-Sim et al (2006) found that 32% of schizophrenics also suffered from an additional mental disorder.
-Comorbidity could also mean that an additional mental disorder is masked and therefore left undiagnosed and untreated.
- This questions the validity of diagnosis when comorbidity exists.
A03 - What is symptom overlap?
– Many of the symptoms of Sz are also found in many other
disorders, such as depression and bipolar disorder.
-This issue is referred to as symptom overlap.
- Most people who are diagnosed with schizophrenia have sufficient symptoms of other disorders that they could also receive at least one other diagnosis.
