Abstract
Active comparators are often included in phase 2 studies as a positive control to assess assay sensitivity, but inclusion of a positive control does not necessarily improve decision making. Examples show that positive controls are more useful in assessing assay sensitivity as the probability the test drug is effective decreases and as power for the contrast of the positive control versus placebo increases. These results suggest that a positive control should be powered at a minimum of 807o, and preferably at 90%. Analogously, a positive control can be used in an estimation framework to assess whether the study performed as expected, thereby indicating whether or not the test drug was assessed under the anticipated conditions. In so doing, the sample would need to be sufficiently large to ensure reliable estimation. The key point again is that results of the positive control must be reliable if they are to be useful, and adding a small sample of patients in a positive control arm can do more harm than good. It is also important to recognize that including a positive control only allows assessment, but not improvement, of assay sensitivity. Actual clinical trial data are used to suggest that two smaller two-arm studies of test drug and placebo instead of one larger study that also includes a positive control may improve assay sensitivity with little to no increase in the total sample size.
Similar content being viewed by others
References
Hurko O, Ryan JI. Translational research in central nervous system drug discovery. NeuroRx. 2005;2:671–682.
Kola I, Landis J. Can the pharmaceutical industry reduce attrition rates? Nat Rev Drug Discov. 2004;3:711–715.
Kemp AS, Schooler NR, Kalali AH. el al. What is causing the reduced drug-placebo difference in recent schizophrenia clinical trials and what can be done about it? Schizophr Bull. Epub ahead of print. August 22, 2008. doi: 10.1093/schbul/ sbn 110.
Temple R, EllenbergSS. PIacebo-controlled trials and active-control trials in the evaluation of new treatments. Part 1: ethical and scientific issues. Ann Intern Med. 2000;133:455–463.
Tsong Y, Zhang JJ. Testing superiority and non-inferiority hypotheses in active controlled active trials. Biom J. 2005;47(1 ):62–74.
Hung HMJ, Wang SJ, Tsong Y, Lawrence J, O’Neil RT. Some fundamental issues with non-inferiority testing in active controlled trials. Stat Med. 2003;22 (2):213–225.
International Conference on Harmonization. ICH Efficacy Document E-9. Statistical principles of clinical trials, https://doi.org/www.fda.gov/cder/guidance.
DerSimonian R, Laird N. Meta-analysis in clinical trials. Control Clin Trials. 1986;7(3):177–188.
Sankoh AJ, Huque MF. Impact of multiple end-points on type 1 error rate and power of test statistic in non-superiority clinical trials. Far East J Theor Stat. 2004; 13(1):47–65.
Sankoh AJ. Al-Osh M, Huque FM. On the utility of the Dirichlet distribution for meta-analysis of clinical studies. J Biopharm Stat. I999:9(2):289– 306.
Rohmel J. Therapeutic equivalence investigations: statistical consideration. Stat Med. 1998:17 (15–16): 1703–1714.
Holmgren EB. Establishing equivalence by showing that a specified percentage of the effect of the active control over placebo is maintained. J Binpharm Stat. 1999;9:651–659.
Khan A, Kolts RL, Thase ME, Krishnan KR, Brown W. Research design features and patient characteristics associated with the outcome of antidepressant clinical trials. Am J Psychiatry. 2004;161: 2045–2049.
Goldstein DJ. Mallinckrodt C, Lu Y, Demilrack MA. Duloxetine in the treatment of major depressive disorder: a double-blind clinical trial. J Clin Psychiatry. 2002;63(3):225–231.
Goldstein DJ, Lu Y, Detke MJ, Wiltse C, Mallinckrodt C, Demitrack MA. Duloxetine in the treatment of depression: a double-blind placebo-controlled comparison with paroxetine. J Clin Psychopharmacol 2004;24:389–399.
Detke MJ, Wiltse CG, Mallinckrodt CH, McNa-mara RK, Demitrack MA. Bitter 1. Duloxetine in the acute and long-term treatment of major depressive disorder: a placebo and paroxetine-con-trolled trial. Eur Neuropsychopharmacol. 2004;14: 457–470.
Perahia DC, Wang F, Mallinckrodt CH, Walker DJ, Detke MJ. Duloxetine in the treatment of major depressive disorder: a placebo- and paroxeline-conl rolled trial. Eur Psychiatry. 2006;21:367–378.
Nierenberg AA, Greist JH, Mallinckrodt CH.et al. Duloxeline versus escilalopram and placebo in the treatment of patients with major depressive disorder: onset of antidepressant action, a non-inferiority study. Curr Med Res Opin. 2007;23: 401–416.
Detke MJ, Lu Y, Goldstein DJ, Hayes JR, Demitrack MA. Duloxeline. 60 mg once daily for major depressive disorder: a randomized double-blind placebo-controlled trial. J Clin Psychiatry. 2002; 63:308–315.
Detke MJ, Lu Y, Goldstein DJ, McNamara RK, Demilrack MA. Duloxeline 60 mg once daily dosing versus placebo in the acute treatment of major depression. J Psychiatr Res. 2002;36:383– 390.
Raskin J, Willse CG, Siegal A. et al. Efficacy of duloxetine on cognition, depression, and pain in elderly patients wild major depressive disorder: an 8-week, double-blind, placebo-controlled trial. Am J Psychiatry. 2007;164:900–909.
Nemeroff CB, Schatzberg AE, Goldstein DJ. et al. Duloxetine for the treatment of major depressive disorder. Psychopharmacol Bull. 2002;56:106– 132.
Mallinckrodt CH, Prakash A, Houston JP, Swindle R, Delke MJ, Fava M. Differential antidepressant symptom efficacy: placebo-controlled comparisons of duloxetine and SSRls (fluoxetine, paroxetine, escilalopram). Neuropsychobiology. 2007;56 (2–3): 73–85.
Eli Lilly and Company. A study comparing dulox-etine and placebo in assessing energy and vitality in MDD patients. ClinicalTrials.gov. Bethesda. MD: National Library of Medicine; 2000. https://doi.org/clinicaltrials.gov/show/NCT00536471.
Bech P, Kajdasz DK, Porsdal V, Dose-response relationship of duloxetine in placebo-controlled clinical trials in patients with major depressive disorder. Psychapharmacology (Berl). 2006:188: 273–280.
Entsuah R, Shaffer M, Zhang J. A critical examination of the sensitivity of unidimensional sub-scales derived from the Hamilton Depression Rating Scale to antidepressant drug effects. J Psy-chiatr Res. 2002;36:437–448.
Paries D, Herrera J, Rayamajhi J, DeBrota D, Demitrack M, Potter WZ. The responsiveness of the Hamilton Depression Rating Scale. J Psychiatr Res.2000;34(1):3–10.
Mallinckrodt CH, Meyers AL, Prakash A, Faries DE, Detke MJ. Simple options for improving signal detection in antidepressant clinical trials. Psychopharmcol Bull 2007;40(2): 101 –114.
Maier W, Philipp M. Improving the assessment of seventy of depressive states; a reduction of the Hamilton Depression Scale. Pharmacopsychiatry. 1985;18:114–115.
Papakostas GI, Fava M. Does the probability of receiving placebo influence clinical trial outcome? A meta-regression of double-blind, randomized clinical trials in MDD. Eur Neuropsycho-pharmacol 2009;19(1):34–40.
Khan A, Detke M, Khan SR, Mallinckrodt C. Placebo response and antidepressant clinical trial outcome.J Nerv Ment Dis. 2003; 191 (4):211 –218.
Khan A, Khan SR, Walens G, Kolts R, Giller EL. Frequency of positive studies among fixed and flexible dose antidepressant clinical trials: an analysis of the food and Drug Administration summary basis of approval reports. Neuropsycho-pharmacology. 2003;28:552–557
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Mallinckrodt, C.H., Detke, M.J., Prucka, W.R. et al. Considerations for Using Positive Controls in Phase 2 Clinical Trials of Central Nervous System Disorders. Ther Innov Regul Sci 44, 431–441 (2010). https://doi.org/10.1177/009286151004400407
Published:
Issue Date:
DOI: https://doi.org/10.1177/009286151004400407