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MEASURING IMPAIRMENT: VALIDATED TEST METHODS FOR ASSESSING SEDATING MEDICATIONS PowerPoint PPT Presentation


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MEASURING IMPAIRMENT: VALIDATED TEST METHODS FOR ASSESSING SEDATING MEDICATIONS. Gary G. Kay, Ph.D. Associate Clinical Professor of Neurology Director, Neuropsychology Division Georgetown University School of Medicine Washington, DC & President Washington Neuropsychological Institute

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MEASURING IMPAIRMENT: VALIDATED TEST METHODS FOR ASSESSING SEDATING MEDICATIONS

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MEASURING IMPAIRMENT: VALIDATED TEST METHODS FOR ASSESSING SEDATING MEDICATIONS

Gary G. Kay, Ph.D.

Associate Clinical Professor of Neurology

Director, Neuropsychology Division

Georgetown University School of Medicine

Washington, DC

&

President

Washington Neuropsychological Institute

Washington, DC

FDA/NTSB PUBLIC HEARING: Transportation Safety and Potentially

Sedating or Impairing Medications, November 14-15, 2001, Washington, DC


Definition of Sedation

  • Depression of brain functioning by a medication, manifested by:

    • sleepiness, drowsiness, fatigue

    • slowed brain activity

    • reduced wakefulness

    • impaired performance


Evaluating Sedation

  • Self-report measures

  • Physiologic measures

  • Performance measures


Evaluating Sedation

  • Self-report measures

    • Diary Cards

    • Rating Scales, Mood Inventories

    • Visual Analog Scales

    • Personal Data Assistant (Palm Pilot)

    • Prescription Event Monitoring


Evaluating Sedation:Self-Report Measures

Problems with self-report

  • Subjectivity

  • Self-report bias

  • Validity – Self-report frequently is not consistent with physiological and performance evidence of sedation


Cognitive Performance:Changes From Baseline in Non-Sleepy Patients

Day 1 Treatment Effects

Diphenhydramine

Loratadine

Placebo

.4

.2

0

-2

Factor Score (mean change

from baseline)

-.4

  • Factor

    • Divided attention/working memory

    • Vigilance

    • Speed

-.6

-.8

-1.0

Kay, et al. AAAAI. 1999.


Evaluating Sedation:Physiologic Measures

  • EEG (e.g., continuous EEG for microsleeps)

  • Evoked potentials (e.g., P300)

  • Functional brain imaging (e.g., PET and fMRI)

  • Multiple sleep latency test (MSLT)

  • Activity monitors (e.g., wrist actigraph)


MULTIPLE SLEEP LATENCY TESTAVERAGE NUMBER OF MINUTES TO FALL ASLEEP

p=.007

p=.003


SELF-REPORTED SLEEPINESSSTANFORD SLEEPINESS SCALE (8:30 AM TEST)

p=.04


Functional MRI:Mental Arithmetic Test

Change From Baseline to Day 3 of AM-PM Dosing:

Frontoparietal Brain Activation

150

Placebo

P = .002

CP 8 mg/TF

100

CP 12 mg/TF

P = .009

50

Pixel activation

0

-50

-100

Starbuck, et al. AAAAI. 1998.


Evaluating Sedation:Performance Measures

  • Simulation (e.g., driving, flying)

  • Cognitive testing*

  • Psychomotor testing*

    *Computer-based cognitive and psychomotor testing is employed by pharmaceutical industry and FDA to assess CNS effects


Comparison of the Acute and Steady-State Effects of Loratadine, Diphenhydramine, and Placebo

  • Assess the cognitive, psychomotor, and subjective effects of these antihistamines.

  • Determine the relationship between self-reported sedation and cognitive performance.

Subjects (N=98) were randomly assigned to one of the 3 treatment groups:

  • 10 mg loratadine

  • 50 mg diphenhydramine on Day 1, followed by 25mg 4x/day on Days 2-5

  • placebo

Kay, et al. Arch Intern Med. 1997.


Better

functioning

Poorer

functioning

Day 1:Change in Factor Scores

Mood &

Working

Divided

sedation

Speed

memory

attention

0.4

0.3

0.2

0.1

0

Factor scores, z-score units

-0.1

-0.2

-0.3

Diphenhydramine

-0.4

Loratadine

-0.5

Placebo

-0.6

Kay, et al. Arch Intern Med. 1997.


Vigilance: Continuous Performance Test Accuracy

Day 1 Results

Diphenhydramine

100

Loratadine

98

Placebo

96

94

CPT accuracy, %

92

90

88

86

84

Kay, et al. Arch Intern Med. 1997.


CRITICAL COGNITIVE DOMAINS

FOR DEMONSTRATING SEDATION

VIGILANCE: Capacity to sustain attention under conditions of minimal arousal (e.g., monotonous tasks).

DIVIDED ATTENTION: Ability to perform simultaneous mental activities; also referred to as dual tasking.

WORKING MEMORY: Ability to hold information temporarily in one’s head for purposes of using the information in a calculation, or other mental activity.


Consistent Neuropsychological Findings with Sedating Medications

  • Tests of vigilance (i.e., lapses of attention) appear to be the most sensitive measures for detecting the sedation effects that may contribute to accidents.

  • Psychomotor effects (i.e., disruption of tracking) appear to persist (for weeks) after adaptation has occurred to cognitive effects.


Summary

  • Sedating medications can cause impairment in the absence of sleepiness.

  • Sedating (OTC and Rx) medications don’t only cause sleepiness. They impair alertness, cognitive and psychomotor functioning.

  • Sedating effects may carry over to the following day even when medications are taken at night.

  • Vigilance, divided attention, and working memory are especially vulnerable to sedating medications

  • Assessment of sedation effects (and consumer/ prescriber information about sedation) should be based on more than self-report findings.


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