Reliability/validity in diagnosis/classification of sz

• Diagnosis - The identification of the nature of an illness or other problem by examination of the symptoms eg someone reporting hearing voices
• Classification - The action or process of classifying something: the classification of disease according to symptoms eg. a symptom of sz is hallucinations
• Reliability in diagnosis

  > Refers to consistency

  > Whether we can gain consistent results when classifying and diagnosing sz

  > The extent to which different classification systems agree upon how schizophrenia should be classified and the extent to which two or more health professionals would agree on the same diagnosis, regardless of time period or culture, measured by inter-rater reliability
• Validity in diagnosis

  > Refers to accuracy

  > The extent to which we are measuring what we intend to measure (schizophrenia).

  > For example, are the classification systems accurately outlining the signs and symptoms of schizophrenia and are health professionals’ accurately diagnosing schizophrenia
• Research

  > Cheniaux asked two psychiatrists to diagnose the same 100 patients using the DSM and ICD

  > One psychiatrist diagnosed 26 according to DSM and 44 according to ICD. The other diagnosed 13 according to DSM and 24 according to ICD.

  > Poor inter-rater reliability as one psychiatrist diagnosed almost double the amount than the other psychiatrist.

  > It demonstrates poor reliability in the classification of schizophrenia as both psychiatrists diagnosed almost double the number of patients using the ICD than the DSM, which also calls in to question the validity of the diagnosis.
• Symptom overlap - Two or more conditions share similar symptoms

  > Eg. schizophrenia and depression involve negative symptoms such as avolition
• Co-morbidity - This is where two illnesses/conditions occur at the same time

  > Schizophrenia is commonly diagnosed with other conditions such as depression and/or OCD as they share common symptoms i.e. lowered motivation/mood

  > This is a problem as it means that schizophrenia may not exist as a distinct condition which may lead to misdiagnosis.
• Reliability/ Validity AO3

  :( Often symptom overlap

  > Where two or more conditions share similar symptoms

  > For example both schizophrenia and depression involve negative symptoms such as avolition

  > Therefore questioning the reliability and validity of the classification of sz because an individual may be diagnosed with the wrong disorder

  > This weakens the validity and reliability in the classification and diagnosis of schizophrenia as it negatively affects its accuracy and consistency
• Reliability/ Validity AO3

  :( Co-morbidity

  > This is where two illnesses/conditions occur at the same time

  > Buckley concluded that 50% of patients diagnosed with schizophrenia also have a diagnosis of depression and 23% of patients diagnosed with schizophrenia are diagnosed with OCD.

  > This questions the validity and reliability of classification and diagnosis of schizophrenia, because the two conditions may be better seen as one and doctors may diagnose the wrong condition
• Reliability/ Validity AO3

  :( Gender bias

  > More men have been diagnosed with sz then women

  > This may be because men are more genetically vulnerable to developing schizophrenia than women.

  > However, it could be because females with schizophrenia typically function better than men, being more likely to work and have good family relationships therefore their symptoms may be masked

  > This questions the validity and reliability of the classification and diagnosis of schizophrenia as women who share similar symptoms as men may not receive the same diagnosis as their symptoms seem mild.