The Value of Small Clinical Trials

  • K. D. MacRae
Part of the Recent Results in Cancer Research book series (RECENTCANCER, volume 111)


Large clinical trials and overviews which pool several clinical trials addressing substantially the same question have an important role in clinical research, viz., the detection of small or moderate differences between treatments where the outcome is an important one, such as survival. Also, large numbers give narrow confidence intervals for the estimate of the treatment effect. However, small clinical trials still have an important part to play. Firstly, pilot studies need to be carried out before a large trial is begun. Secondly, in the treatment of certain diseases, especially where treatment is aimed at relief of symptoms, it may be felt that only large differences between treatments are of interest. Thirdly, it may be difficult to carry out a large clinical trial because of ethical or other problems, but a small trial may be able to provide useful pragmatic information. The important statistical concepts are the confidence interval for the estimated treatment difference and the type-III error.


Error Probability Treatment Difference Large Clinical Trial Pragmatic Trial Small Clinical Trial 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Collins R, Langman M (1985) Treatment with histamine H2 antagonists in acute upper gastrointestinal hemorrhage. N Engl J Med 313: 660–666PubMedCrossRefGoogle Scholar
  2. Detsky AS, Sackett DL (1985) When was a ‘negative’ clinical trial large enough? Arch Intern Med 145: 709–712PubMedCrossRefGoogle Scholar
  3. Freiman JA, Thomas AB, Chalmers TC, Smith H, Keubler RR (1978) The importance of beta, the type-II error and sample size in the design and interpretation of the randomized controlled trial. N Engl J Med 299: 690–694PubMedCrossRefGoogle Scholar
  4. Gardner MJ, Altman DG (1986) Confidence intervals rather than P values: estimation rather than hypothesis testing. Br Med J 292: 746–750CrossRefGoogle Scholar
  5. Lachin JM (1981) Introduction to sample size determination and power analysis for clinical trials. Controlled Clin Trials 2: 93–113PubMedCrossRefGoogle Scholar
  6. Makuch RW, Johnson MF (1986) Some issues in the design and interpretation of ‘negative’ clinical studies. Arch Intern Med 146: 986–989PubMedCrossRefGoogle Scholar
  7. Powell-Tuck J, MacRae KD, Healy MJR, Lennard-Jones JE, Parkins RA (1986) A defence of the small clinical trial: evaluation of three gastroenterological studies. Br Med J 292: 599–602CrossRefGoogle Scholar
  8. Schwartz D, Lellouch R (1967) Explanatory and pragmatic attitudes in therapeutic trials. J Chronic Dis 20: 637–648PubMedCrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin · Heidelberg 1988

Authors and Affiliations

  • K. D. MacRae
    • 1
  1. 1.Charing Cross and Westminster Medical SchoolLondonGreat Britain

Personalised recommendations