Center for Clinical Epidemiology and Biostatistics - PowerPoint PPT Presentation

Loading...

PPT – Center for Clinical Epidemiology and Biostatistics PowerPoint presentation | free to download - id: 56c690-OWYyN



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Center for Clinical Epidemiology and Biostatistics

Description:

Chair and Professor, Department of Biostatistics and Epidemiology Director, Center for Clinical Epidemiology and Biostatistics George S. Pepper Professor of Public ... – PowerPoint PPT presentation

Number of Views:458
Avg rating:3.0/5.0
Slides: 25
Provided by: BrianL53
Learn more at: http://www.fda.gov
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Center for Clinical Epidemiology and Biostatistics


1
Brian L. Strom, M.D., M.P.H. Chair and Professor,
Department of Biostatistics and
Epidemiology Director, Center for Clinical
Epidemiology and Biostatistics George S. Pepper
Professor of Public Health and Preventive
Medicine Professor of Biostatistics and
Epidemiology, Medicine, and Pharmacology Universi
ty of Pennsylvania School of Medicine
2
Sampling
  1. What is an appropriate sample size of respondents
    to best determine risk of sound and look alike
    proprietary names in the prescription drug study
    group? In a focus group? In a survey document?
  2. Should sample be randomly selected? Is it
    important to have a statistical significance for
    this type of evaluation?

3
(No Transcript)
4
Sampling
  • Introduction
  • Very general principles of sample size
    calculations and sampling
  • Application of general principles to this
    situation
  • Recommendations for research, to guide the future

5
Options in Research Design
  • Analytic Studies
  • Experimental Study
  • Prospective Cohort Study
  • Retrospective Cohort Study
  • Case-Control Study
  • Descriptive Studies
  • Analyses of Secular Trends
  • Case Series
  • Case Reports

6
Factor
Cohort Studies
7
Determinants of NeededSample Size
  • Alpha
  • Beta
  • Variability (SD)
  • Delta--how small a difference do you want to be
    able to detect?

8
Determinants of NeededSample Size Cohort Study
  • Alpha
  • Beta
  • Incidence in the unexposed control group
  • Delta--how small a RR do you want to be able to
    detect?

9
Determinants of Needed SampleSize Case-Control
Study
  • Alpha
  • Beta
  • Prevalence in the undiseased control group
  • Delta--how small a RR do you want to be able to
    detect?

10
Sampling
Study Sample
Statistical Inference
Conclusion About a Population
(Association)
Biological Inference
Conclusion About Scientific Theory
(Causation)
11
Application of GeneralPrinciples to This
Situation
  • THE Central Principleof Research Design The
    question is, what is the question??

12
Application of GeneralPrinciples to This
Situation
  • In this situation, there are no a priori
    hypotheses being tested to be able to consider
    sample size calculations or questions of sampling
  • What is being performed is essentially
    qualitative research

13
Recommendations for Research,to Guide the Future
  • Evaluate the current process in a quantitative
    fashion

14
General Strategy for Evaluation
  • Standardize procedure
  • Test for reliability/ reproducibility
  • Test for validity
  • Make changes in the procedure accordingly

15
Standardize Procedure
  • Choose among the current possible approaches a
    standard to be evaluated more rigorously

16
Test for Reliability/Reproducibility
  • Evaluate the same drug names in the same process
    with multiple different groups of survey
    prescribers and experts, to look for whether
    there is adequate agreement
  • If no reliability, validity is impossible and
    procedure should be abandoned

17
Test for Validity
  • Gold standard needed
  • Drug names rejected in initial FDA review
  • Drug names withdrawn due to problems
  • Direct measurement of error rate

18
Retrospective Drug NamesRejected in Initial FDA
Review
  • Problem was the initial review decision correct?

19
Retrospective Drug NamesWithdrawn Due to
Problems
  • Knowledge of reviewers could be problematic
  • Other countries
  • Years ago, and using new pharmacists
  • Was the withdrawal decision a correct one?

20
Prospective DirectMeasurement of Error Rate
  • Simulate real life situation in a study setting
  • Choose good and bad options for new names
  • Enter possible new names into prescription entry
    computer program
  • Ask large numbers of docs to write orders
  • Ask large numbers of pharmacists to fill each
    rx, entering into prescription entry computer
    program
  • Directly measure resulting error rate

21
Make Changes in theProcedure Accordingly
  • Determine appropriate cutpoint for expert
    ratings, ROC curve vs. gold standard
  • Determine appropriate sample sizes through
    simulation, ie how many are needed to achieve
    results consistent with the gold standard
  • Modify processes accordingly

22
Potential Sources of Support
  • FDA extramural funds
  • AHRQ patient safety funds
  • NIA pharmacology program
  • NIGMS pharmacology program

23
Conclusions
  • Applying a quantitative approach to evaluating
    what has so far been a qualitative one, could
    lead to major changes in the procedure, and major
    improvements in the net results

24
Statitsically incorrect
About PowerShow.com