International Journal of Physiotherapy and Research



Welcome to International Journal of Physiotherapy and Research

b2



b3

Type of Article : Review

Year: 2015 | Volume 3 | Issue 5 | Page No. 1198-1207

Date of Publication: 11-10-2015

DOI: 10.16965/ijpr.2015.173

TREATMENT EFFECTS 101

Thelma J. Mielenz *1, Janet K. Freburger 2, Timothy S. Carey 2,3.  
*1 Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, New York 10032.
2 Cecil G. Sheps Center for Health Services Research, University of North Carolina, Chapel Hill, North Carolina 27599.
3 Departments of Medicine and Social Medicine, University of North Carolina, Chapel Hill, North Carolina 27599.

Corresponding author: Thelma J. Mielenz, PhD, Department of Epidemiology, Mailman School of Public Health, Columbia University, 722 West 168th Street, New York, NY 10032, Phone: 212-342-0169, Fax: 212-342-5168.
E-Mail:
tjm2141@columbia.edu

Abstract:

Physical therapy researchers are interested in how beneficial an intervention is or the “treatment effect.”  There are many measures of treatment effect that are applicable for understanding the efficacy and effectiveness of health interventions. Given that each treatment effect has its own set of advantages and disadvantages, understanding these characteristics can help guide which measure is most appropriate for a specific study. This article presents the more common treatment effects for both dichotomous and continues outcomes.  The overall aim is to serve as a guide to newer physical therapy researchers on using and interpreting treatment effects.
KEY WORDS: Treatment effects, Relative measures of effect, Absolute measures of effect.

References

  1. Streiner DL, Norman GR. PDQ Epidemiology. 3rd ed. Shelton: People's Medical Publishing House; 2009.
  2. Sterne JA, Davey Smith G. Sifting the evidence-what's wrong with significance tests? BMJ. Jan 27 2001;322(7280):226-231.
  3. Rosenthal R, Rosnow RL, Rubin DB. Contrasts and effect sizes in behavioral research: A correlational approach. Cambridge, United Kingdom: Cambridge University Press; 2000.
  4. Walter SD. Choice of effect measure for epidemiological data. J Clin Epidemiol. Sep 2000;53(9):931-939.
  5. Guyatt GH, Juniper EF, Walter SD, Griffith LE, Goldstein RS. Interpreting treatment effects in randomised trials. BMJ. Feb 28 1998;316(7132):690-693.
  6. Sinclair JC, Bracken MB. Clinically useful measures of effect in binary analyses of randomized trials. J Clin Epidemiol. Aug 1994;47(8):881-889.
  7. Rothman  KJ, Greenland S, Lash TL. Modern Epidemology. 3rd ed. Philadelphia: Lippincott Williams & Wilkins; 2008.
  8. Rothman KJ GS. Modern Epidemiology. 2nd ed. Philadelphia: Lippincott-Raven; 1998.
  9. Fleiss JL, Levn B, Cho Paik M. Statistical Methods for Rates and Proportions. 3rd ed. New York: John Wiley & Sons; 2003.
  10. Pagano M, Gauvreau K. Principles of Biostatistics. 2nd ed. Pacific Grove: Duxbury; 2000.
  11. Last JM. A Dictionary of Epidemiology. 4th ed. New York: Oxford University Press, Inc.; 2001.
  12. Greenland S. Quantitative methods in the review of epidemiologic literature. Epidemiol Rev. 1987;9:1-30.
  13. Zhang J, Yu KF. What's the relative risk? A method of correcting the odds ratio in cohort studies of common outcomes. JAMA. Nov 18 1998;280(19):1690-1691.
  14. Sackett DL SS, Richardson WS, Rosenberg W, Haynes RB. Evidence-based Medicine: How to Practice and Teach EBM. 2nd ed. London: Churchill Livingstone; 2000.
  15. Le CT. Applied Survival Analysis. New York: John Wiley & Sons; 1997.
  16. Walter SD, Irwig L. Estimating the number needed to treat (NNT) index when the data are subject to error. Stat Med. Mar 30 2001;20(6):893-906.
  17. Chatellier G, Zapletal E, Lemaitre D, Menard J, Degoulet P. The number needed to treat: a clinically useful nomogram in its proper context. BMJ. Feb 17 1996;312(7028):426-429.
  18. Davies HT, Crombie IK, Tavakoli M. When can odds ratios mislead? BMJ. Mar 28 1998;316(7136):989-991.
  19. Deeks J. When can odds ratios mislead? Odds ratios should be used only in case-control studies and logistic regression analyses. BMJ. Oct 24 1998;317(7166):1155-1156; author reply 1156-1157.
  20. Fletcher RH, Fletcher SW, Wagner EH. Clinical Epidemiology: The Essentials. 3rd ed. Baltimore: Williams & Wilkins; 1996.
  21. Jaeschke R, Guyatt G, Shannon H, Walter S, Cook D, Heddle N. Basic statistics for clinicians: 3. Assessing the effects of treatment: measures of association. CMAJ. Feb 1 1995;152(3):351-357.
  22. Smeeth L, Haines A, Ebrahim S. Numbers needed to treat derived from meta-analyses--sometimes informative, usually misleading. BMJ. Jun 5 1999;318(7197):1548-1551.
  23. Coe R. What is 'effect size'? 2000; http://www.cem.dur.ac.uk/ebeuk/research/effectsize/ESguide.htm, July 1, 2011.
  24. Becker LA. Effect Size. 2000; http://www.web.uccs.edu/becker/psy590.es.htm. Accessed July 1, 2011.
  25. Rosnow RL, Rosenthal R, Rubin D. B. Contrasts and correlations in effect-size estimation. Psychol Sci. Nov 2000;11(6):446-453.
  26. Rosnow RL, R. R. Computing contrasts, effect sizes, and counternulls on other people's published data: General procedures for research consumers. Pyschological Methods. 1996;1:331-340.
  27. Rosenthal R, Rubin DB. Meta-analytic procedures for combining studies with multiple effect sizes. Psychological Bulletin. 1986;99:400-406.
  28. Garrett J. Bios 141: Quantitative methods for healtchare professionals I. Chapel Hill: University of North Carolina at Chapel Hill;1999.
  29. Greenland S. Interpretation and choice of effect measures in epidemiologic analyses. Am J Epidemiol. May 1987;125(5):761-768.
  30. Greenland S, Schlesselman JJ, Criqui MH. The fallacy of employing standardized regression coefficients and correlations as measures of effect. Am J Epidemiol. Feb 1986;123(2):203-208.
  31. Schulzer M, Mancini GB. 'Unqualified success' and 'unmitigated failure': number-needed-to-treat-related concepts for assessing treatment efficacy in the presence of treatment-induced adverse events. Int J Epidemiol. Aug 1996;25(4):704-712.
  32. Gordis L. Epidemiology. 3rd ed. Philadelphia: W.B. Saunders Company; 2004.
  33. Merrill RM. Introduction to Epidemiology. 5ht ed. Sudbury: Jones and Bartlett Publishers, LLC; 2010.
  34. Last JM. A Dictionary of Epidemiology. 3rd ed. New York: Oxford University Press, Inc.; 1995.

 

Thelma J. Mielenz, Janet K. Freburger, Timothy S. Carey. TREATMENT EFFECTS 101. Int J Physiother Res 2015;3(5):1198-1207. DOI: 10.16965/ijpr.2015.173

b2



b3




Search

Volume 1 (2013)

Volume 2 (2014)

Volume 3 (2015)

Submit Manuscript