Reliability And Validity Of Diagnosis Flashcards
How is reliability measured in diagnosis
Inter rater reliability- 2 clinicians agree on the same diagnosis
What does a reliability score of 0.6 mean
That a patient judged as having schizophrenia by one clinician has a 60% chance of being diagnosed the same by another
What are two issues of diagnosis reliability
Patient factors- info given to clinicians by patients may be inaccurate due to memory problems or denial and shame.
Clinicians use unstructured interviews leading to focus on certain symptom presentation e.g might focus on nightmares whilst another might focus on a traumatic past event
Give 2 positive studies into reliability of diagnosis
Goldstein- single blind technique testing reliability of DSM 3. 2 experts rediagnosed 8 patients who were diagnosed with schizophrenia in DSM 2. Found a high level of agreement
Brown et al- reliability and validity of DSM 4 diagnosing anxiety and mood disorders. Most categories good to excellent reliability. Only disagreements were not what symptoms were but whether there were enough symptoms
Give two negative studies in reliability of diagnosis
Cooper- schizophrenia- reliability estimate of 0.81 in DSM 3 trial and only 0.46 in DSM 5 trial. Meaning that DSM 5 is not as reliable
Kupfer- some disorders have symptoms that vary a lot over weeks so it is harder to find reliability. E.g autism spectrum have good reliability in trials using DSM 5 but anxiety disorders had low
Why would a diagnosis be valid?
If it correctly reflects an actual disorder. Meaning symptoms of patient match those considered to be present
What does a valid diagnosis predict
The course of a disorder in real life and the treatment suggested by diagnosis is effective in real life
What are the 4 types of diagnosis validity
Predictive validity
Aetiological validity
Concurrent validity
Convergent validity
What is concurrent validity?
Results of a study agree with results from another study. E.g diagnosis from DSM 5 comes up with same diagnosis with ICD 10
What is predictive validity
The extent to which results from a test can predict future behaviour.
What is aetiological validity
The extent to which a disorder has the same cause or causes. E.g people who have schizophrenia all have excess dopamine in brain
What is convergent validity
Two measures of the same construct agree with one another.
What are 3 issues with validity in diagnosis
Co-morbidity- hard to diagnose using DSM
Patients are not honest and do not divulge all info to clinicians. Due to cultural reasons, denial or shame
Reductionist- splitting a mental disorder into symptoms
What are two positive studies on validity of diagnosis
Kim cohen- conduct disorder in 5 year olds through DSM 4. More likely to have behaviour problems at the age of 7 showing predictive validity
Layey- children with ADHD and found good predictive validity in relation to social and academics over a six year period
Give two negative studies into validity of diagnosis
Rosenhan- DSM 2 was not valid as nurses using it couldn’t distinguish between those who had mental disorder and those who didn’t
Andrews- assessing concurrent validity- poor agreement on post traumatic stress disorder, validity depends on disorder- DSM 5 and ICD 10
