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Research: VICKERS, Integrative M
Listed in Issue 84
Abstract
VICKERS, Integrative Medicine Service, Memorial Sloane-Kettering Cancer Center, New York, New York 10021, USA, vickersa@mskcc.org, shows how to reduce the number of patients needed for randomized trials.
Background
In a typical trial, patients are assessed for symptom severity at baseline, randomized to treatment or control and reassessed after a suitable follow-up period.
Methodology
Medical statistics.
Results
It can be shown that when patients with chronic conditions are used, as is often the case with complementary therapies, the sample size can be reduced by two ways: repeat measurement and analysis of co-variance (ANCOVA). An example is given of a trial of acupuncture for back pain. Administering a pain questionnaire twice at baseline and four times at follow-up reduces the number of patients required by about 20%. A further 10% reduction is obtained by the use of ANCOVA.
Conclusion
It is desirable to reduce the number of patients required for a randomized controlled trial by a third; however ANCOVA is complex and expert statistical help is needed.
References
Vickers A. How to reduce the number of patients needed for randomized trials: a basic introduction. Complementary Therapies in Medicine 9 (4): 234-236, Dec 2001.
