Formal Diagnostic Assessment

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Formal Diagnostic Assessment

• Based on
• life history facts
• signs (objectively observable abnormalities)
  symptoms (subjective abnormalites), present
  past
• abnormal personality traits
• 3 ways to get diagnosis
• Inattention to criteria unstructured interview
• Criteria unstructured interview
• Criteria structured interview

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Example Diagnosis (No Criteria, DSM-II)
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Example Diagnosis (DSM-IV Criteria)
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DSM-IV Criteria, contd
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DSM-IV Criteria, contd
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DSM-IV Criteria, contd
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Traditional Diagnostic Interview

• Patient identification
• Chief complaint
• History of present illness
• Past illnesses
• Social history
• Medical history
• Family history

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Diagnostic Interview, contd

• Mental Status Exam (see next slide)
• Impression
• definite, or rule outs
• Plan (treatment, referral, etc.)
• The unstructured interview takes 4590 min
• Only pursuing 1 or 2 problem areas
• Only asking enough questions to establish likely
  diagnosis

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Mental Status Exam

• Appearance
• Consciousness level
• Cooperativeness
• Speech abnormalities
• Cognitive abnormalities

• Judgment abnormalities
• Content of thought
• Mood affect
• Psychotic features

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Structured Interviews

• Tied to particular sets of criteria (e.g.,
  Research Diagnostic Criteria, DSM-IV)
• Such interviews spell out
• What questions to ask
• What order to ask them in
• (Often) how to ask them, how to follow them up
• (Often) how to interpret (code) the answers

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Example Structured Clinical Interview for DSM-IV

• About 100 pages
• Covers affective, psychotic, psychoactive
  substance use, anxiety, somatoform, eating,
  adjustment disorders
• Nominally takes 1 hr, usually 24 hr
• Used in much research, some clinical work

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Disadvantages of Structured Interviews

• Long
• Boring for clinician
• Some allege they interfere with client rapport
  (balk data refute this)
• May not cover all disorders appropriate for
  particular clients

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Advantages (?) of Structured Interviews

• May be more reliable than unstructured (scant
  evidence)
• Much better ability to follow criteria
• More symptoms, diagnoses found
• Higher clinician confidence in assessment
• No evidence that it leads to better client
  outcomes/better prediction of future behavior

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Reliability of Diagnoses

• Vary over wide range, from zero to .90, even
  within studies
• Somewhat better with criteria than without, on
  average
• For diagnoses made without criteria, reliability
  not as bad as often claimed
• Reliability at best mediocre for Axis II
  diagnoses (.6 down to 0), and for some Axis I
  diagnoses as well

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Validity of Diagnoses

• Difficult to assess, absent gold standard
• Need well-replicated data to assess
• Clinical studies of discreteness of syndromes,
  overlap with other syndromes
• Genetic/Family studies
• Etiological/Laboratory studies
• Course outcome studies
• Treatment response studies? (hard to interpret)

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Spitzer on Establishing Validity

• To establish a yardstick in diagnostic validation
  studies
• Cant use RDC or DSM as criterion, since its
  these we wish to test
• LEAD rather than gold standard
• Longitudinal (course of illness over time)
• Expert (clinicians)
• All Data (multiple informants, family history,
  etc.)

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Problems With Nomenclatures

• Exuberant growth of diagnostic lists
• Feighner (St. Louis group) criteria 14
  diagnoses, importantly including Undiagnosed
• Research Diagnostic Criteria 26 diagnoses,
  including two other diagnoses
• DSM-III 207 (!) diagnoses, including NOS
  diagnoses
• DSM-IV 400 diagnoses

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Nomenclature Problems, contd

• Inclusion of many totally unvalidated disorder
  categories (e.g., dependent personality disorder)
• Existence of many, only weakly validated,
  categories (e.g., multiple personality disorder)
• Existence of many wastebasket categories
  other, atypical, especially not otherwise
  specified

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Problems with Classifications

• Question of true structure of phenomena of mental
  disorders
• Categorical?
• Dimensional?
• Some of both?
• Which disorders are of which kind?

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Problems with Diagnostic Process

• Errors/fallacies
• Ignoring base rates, failing to properly adjust
  for them Barnum statements (Meehl)
• Biases e.g., confirmatory overweighting (,)
  cell in mis-estimating correlations
  overpathologizing acceding to authority
• Heuristics e.g., representativeness
  availability anchoring adjustment
• Illusory correlation illusion of validity in
  the absence of meaningful feedback

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Problems with Diagnostic Process, contd

• Lack of demonstrable relationship of
• Experience to judgment accuracy
• (Almost) all training to judgment accuracy
• Impact of non-rational factors on diagnosis
• Stereotyping
• Under/overpathologizing
• Overstatement of diagnosis in third-party
  reimbursement diagnostic creep

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Problems with Diagnostic Process, contd

• Reliance on client report for too many crucial
  data
• Near impossibility of substantiating many
  reported data (e.g., PTSD trauma)
• Consequent vulnerability to faking bad
  (exaggeration, malingering) faking good
  (defensiveness, denial)

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In Defense of Diagnosis

• The better is the enemy of the good
• Critics offer no replacement for nomenclature
  that
• Will likely have notably better validity, etc.
• Will cure diagnosiss drawbacks, without causing
  equally vexing problems of some other kind
• Will be practical
• Ready to go (not pie-in-sky plan for potential
  replacement)
• User-friendly for clinical practice

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In Defense of DSM

• Compare DSM not to pre-drawing-board
  alternatives compare to predecessors
• Advantages of DSM-III et seq. over DSM-II
• Clearer, more communicative
• More informative (manual diagnoses)
• Somewhat more reliable, for many diagnoses
• If followed strictly, eliminates various biases
  (e.g., diagnostician race bias in diagnosing
  schizophrenia)