Discuss validity and reliability of diagnosis with reference to one or more studies - ERQ

Validity

Refers to how accurately a diagnosis reflects a true clinical disorder.

Reliability

Refers to how consistently different clinicians diagnose the same disorder across time or situations.

Accurate Diagnosis

Ensures effective treatment, ethical practice, and prevents harm due to misdiagnosis or stigma.

Classification Systems

Commonly used systems include DSM (Diagnostic and Statistical Manual), ICD (International Classification of Diseases), and specialized systems like GOS.

Inter-rater Reliability

The degree to which different clinicians give the same diagnosis to a patient.

Test-retest Reliability

Whether the same diagnosis is given to a patient when assessed more than once.

Importance of Reliability

Unreliable diagnoses can lead to inconsistent treatment and undermine trust in the system.

Aim of the Nicholls et al. (2000) Study

To investigate inter-rater reliability in diagnosing eating disorders in children.

Sample in the Nicholls Study

81 children aged 7-16 from eating disorder clinics.

Diagnostic Manuals Compared in Nicholls et al.

DSM-IV, ICD-10, and the GOS (Great Ormond Street Hospital) system.

Design of the Nicholls et al. Study

Three clinicians assessed each child independently using different diagnostic systems.

Highest Inter-rater Reliability in Nicholls Study

The GOS system.

Lowest Inter-rater Reliability in Nicholls Study

ICD-10.

Conclusion from the Nicholls Study

Standard manuals may not be reliable for diagnosing children due to developmental symptom differences.

Inappropriateness of DSM and ICD for Children

They emphasize weight and body shape, which may not apply to young children.

Methodological Strength of Nicholls et al.

Clinicians were blind to each other's diagnoses, reducing bias.

Sample bias

Limits generalizability.

Test-retest reliability

Important because symptoms may fluctuate, so a stable diagnosis over time is essential.

Valid diagnosis

Accurately reflects a real and distinct clinical condition.

Consequences of an invalid diagnosis

Can lead to misdiagnosis, incorrect treatment, or missing comorbid conditions.

Symptom overlap

May cause misdiagnosis or multiple incorrect diagnoses.

Aim of Rosenhan's 1973 study

To test the validity of psychiatric diagnosis by seeing if clinicians could tell sane from insane.

Participants in Rosenhan's study

Staff and patients at 12 U.S. psychiatric hospitals; pseudopatients acted as researchers.

Pseudopatients' admission tactic

Faked auditory hallucinations and gave false names and professions.

Pseudopatients' behavior post-admission

Acted normally and reported no further symptoms.

Diagnoses given to pseudopatients

Mostly schizophrenia.

Surprising observation from real patients

Some patients suspected the pseudopatients were faking their illness.

Rosenhan's conclusion

Psychiatric labels can bias diagnosis, and psychiatric diagnosis lacked construct validity.

Methodological strength of Rosenhan's study

Covert observation increased ecological validity.

Ethical issues in Rosenhan's study

Deception, lack of informed consent, and possible harm to staff or real patients.

Relevance of Rosenhan's study today

Highlights issues of label bias and challenges the validity of psychiatric diagnosis.

Cultural factors in diagnosis

Cultural variation in symptom expression can cause misdiagnosis or misinterpretation.

Example of cultural variation in symptom interpretation

Auditory hallucinations may be seen as spiritual in one culture, but pathological in another.

Findings of Rosenhan and Nicholls on diagnosis

Rosenhan shows issues with validity; Nicholls shows issues with reliability in child diagnosis.

Ongoing challenges in diagnosis

Cultural variation, observer bias, and instability of symptoms.

Improvements in modern diagnostic systems

Structured interviews, updated diagnostic criteria, and integration of biological evidence.

Ideal diagnostic system characteristics

Flexible, evidence-based, culturally sensitive, and adaptive to new research.