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9 - Special topics

Published online by Cambridge University Press:  10 May 2010

Mitchell H. Katz
Mitchell H. Katz
Affiliation:
University of California, San Francisco
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Summary

What methods are available for evaluating interventions that do not occur to all subjects at the same time?

It is common in observational cohorts to have different subjects start an intervention at different times, with some subjects never receiving it. This is particularly common when new medications are introduced into practice.

In situations such as these, you may have no subjects on the medication (prior to approval) and then a gradual uptake in medication use. Let's assume you want to evaluate the impact of a new medication designed to prevent osteoporosis. Your outcome is occurrence of a pathologic fracture (yes/no). How would you do it?

At first blush you might think that you could compare the number of fractures in the 280 persons who took the drug to the number of fractures among the 720 persons who did not take the drug.

But this would be wrong from several points of view. First, for those people who dropped out we would only know what happened to them prior to the drop-out (e.g., whether they started taking the medicine, that they didn't develop a fracture). By year 5, some of them may have begun the medicine and some may have had a fracture. We could exclude dropouts from our analysis but then we would lose 15% of our total sample. And what about the deaths that occurred during the study prior to a fracture?

Type
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Information
Evaluating Clinical and Public Health Interventions
A Practical Guide to Study Design and Statistics
 , pp. 135 - 153
Publisher: Cambridge University Press
Print publication year: 2010

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References

Martino, M., Tovo, P.-A., Balducci, M., et al. “Reduction in mortality with availability of antiretroviral therapy for children with perinatal HIV-1 infection.” JAMA 284 (2000): 190–7CrossRefGoogle ScholarPubMed
Piaggio, G., Elbourne, D. R., Altman, D. G., et al. “Reporting of noninferiority and equivalence randomized trials: An extension of the CONSORT statement.” JAMA 295 (2006): 1152–60CrossRefGoogle ScholarPubMed
Kaul, S. and Diamond, G. A. “Good enough: A primer on the analysis and interpretation of noninferiority trials.” Ann. Intern. Med. 145 (2006): 62–9CrossRefGoogle ScholarPubMed
Gøtzsche, P. C. “Lessons from and cautions about noninferiority and equivalence randomized trials.” JAMA 295 (2006): 1172–4CrossRefGoogle ScholarPubMed
Djulbegovic, B. and Clarke, M. “Scientific and ethical issues in equivalence trials.” JAMA 285 (2001): 1206–8CrossRefGoogle ScholarPubMed
Puhan, M. A., Busching, G., Schunemann, H. J., van Oort, E., Zaugg, C., and Frey, M. “Interval versus continuous high-intensity exercise in chronic obstructive pulmonary disease.” Ann. Intern. Med. 145 (2006): 816–25CrossRefGoogle ScholarPubMed
Parienti, J. J., Thibon, P., and Heller, R., “Hand-rubbing with an aqueous alcoholic solution vs traditional surgical hand-scrubbing and 30-day surgical site infection rates: a randomized equivalence study.” JAMA 288 (2002): 722–7CrossRefGoogle ScholarPubMed
Morey, M. C., Snyder, D. C., Sloane, R., et al. “Effects of home-based diet and exercise on functional outcomes among older, overweight long-term cancer survivors.” JAMA 301 (2009): 1883–91CrossRefGoogle ScholarPubMed
Rothman, K. J. “No adjustments are needed for multiple comparisons.” Epidemiology 1 (1990): 43–6CrossRefGoogle ScholarPubMed
Lallermant, M., Jourdain, G., Coeur, S., et al. “Single-dose perinatal nevirapine plus standard zidovudine to prevent mother-to-child transmission of HIV-1 in Thailand.” N. Engl. J. Med. 351 (2004): 217–28CrossRefGoogle Scholar
Montori, V. M., Devereaux, P. J., Adhikari, N. K. J., et al. “Randomized trials stopped early for benefit.” JAMA 294 (2005): 2203–9CrossRefGoogle ScholarPubMed
Wang, R., Lagakos, S. W., Ware, J. H., Hunter, D. J., and Drazen, J. M. “Statistics in medicine – reporting of subgroup analyses in clinical trials.” N. Engl. J. Med. 357 (2007): 2189–94CrossRefGoogle ScholarPubMed
Heitjan, D. F. “What can be done about missing data? Approaches to imputation.” Am. J. Public Health 87 (1997): 548–50CrossRefGoogle ScholarPubMed
Rubin, D. B.Multiple Imputation for Nonresponse in Surveys. New York: Wiley, 1987CrossRefGoogle Scholar
Katz, M. H.Multivariable Analysis: A Practical Guide for Clinicians. Cambridge: Cambridge University Press, 2006: pp. 87–94CrossRefGoogle Scholar
Streiner, D. L. “The case of the missing data: Methods of dealing with dropouts and other research vagaries.” Can. J. Psychiatry 47 (2002): 68–75CrossRefGoogle ScholarPubMed
Molnar, F. J., Hutton, B., and Fergusson, D. “Does analysis using ‘last observation carried forward’ introduce bias in dementia research?” CMAJ 179 (2008)CrossRefGoogle Scholar
Katz, M. H.Multivariable Analysis: A Practical Guide for Clinicians. Cambridge: Cambridge University Press, 2006: pp. 164–71CrossRefGoogle Scholar
Moher, D., Shulz, K. F., and Altman, D., for the CONSORT group. “The CONSORT statement: Revised recommendations for improving the quality of reports of parallel-group randomized trials.” JAMA 285 (2001): 1887–91Google Scholar
Piaggio, G., Elbourne, D. R., Altman, D. G., Pocock, S. J., and Evans, S. J. W., for the CONSORT Group. “Reporting of noninferiority and equivalence randomized trials: An extension of the CONSORT statement.” JAMA 295 (2006): 1152–60CrossRefGoogle ScholarPubMed
Des Jarlais, D. C., Lyles, C., Crepaz, N., and ,the TREND Group. “Improving the reporting quality of nonrandomized evaluations of behavioral and public health interventions: The Trend statement.” Am. J. Public Health 94 (2004): 361–6CrossRefGoogle ScholarPubMed
Elm, E., Altman, D. G., Egger, M., et al. “The strengthening of the reporting of observational studies in epidemiology (STROBE) statement: Guidelines for reporting observational studies.” J. Clin. Epidemiol. 61 (2008): 344–9CrossRefGoogle Scholar
Moher, D., Schulz, K. F., Altman, D., for the CONSORT Group. “The CONSORT statement: revised recommendations for improving the quality of reports of parallel group trials. JAMA (2001) 285: 1987–91CrossRefGoogle Scholar
Lautenschlager, N. T., Cox, K. L., Flicker, , et al. “Effect of physical activity or cognitive function in older adults at risk for Alzheimer disease.” JAMA 300 (2008): 1027–37CrossRefGoogle ScholarPubMed
Marx, R., Hirozawa, A. M., Chu, P. L., Bolan, G. A., and Katz, M. H. “Linking clients from HIV antibody counseling and testing to prevention services.” J. Community Health 24 (1999): 201–13CrossRefGoogle ScholarPubMed

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  • Special topics
  • Mitchell H. Katz, University of California, San Francisco
  • Book: Evaluating Clinical and Public Health Interventions
  • Online publication: 10 May 2010
  • Chapter DOI: https://doi.org/10.1017/CBO9780511712074.010
Available formats
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Save book to Dropbox

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.

  • Special topics
  • Mitchell H. Katz, University of California, San Francisco
  • Book: Evaluating Clinical and Public Health Interventions
  • Online publication: 10 May 2010
  • Chapter DOI: https://doi.org/10.1017/CBO9780511712074.010
Available formats
×

Save book to Google Drive

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.

  • Special topics
  • Mitchell H. Katz, University of California, San Francisco
  • Book: Evaluating Clinical and Public Health Interventions
  • Online publication: 10 May 2010
  • Chapter DOI: https://doi.org/10.1017/CBO9780511712074.010
Available formats
×