Statistics in the News: Chapter 5 Generating New Data: Controlled Experiments
Mind Over Matter
According to popular opinion, the mind can influence the
course of a disease so powerfully that patients can hold off
death by getting emotional support in a group. Some researchers
recently tested the story by designing an experiment involving
235 women with advanced (metastatic) breast cancer. All of
the subjects were expected to live at least 3 months and received
routine medical care. However, a random selection also assigned
158 women to group therapy, while such additional help was
withheld from 77 others. Crucial results are summarized in
Table A.
TABLE A Results of Breast Cancer Study
|
Groups
|
Sample
Size
|
Median Survival
Time
|
Relative Risk Ratio for Death
|
95% Confidence
Interval for Relative Risk Ratio
|
|
Experimental
(received therapy)
|
158
|
17.9 months
|
1.06
|
.78 - 1.45
|
|
Control
(no therapy)
|
77
|
17.6 months
|
1.00
|
--
|
The researchers concluded that psychological intervention
did not prolong survival. The idea that one might cure
cancer in the body by vanquishing it in the mind was nothing
but wishful thinking.
Note: There was, however, a transient effect. Group
therapy did improve the mood and perception of pain among
those who were exceptionally distressed initially. Thus, therapy
improved the quality of life for some, although not its quantity.
Some women lived better, although not longer. In that sense,
mind mattered.
Sources: Adapted from Pamela J. Goodwin et al., "The
Effect of Group Psychological Support on Survival in Metastatic
Breast Cancer," The New England Journal of Medicine,
December 13, 2001, pp. 1719-1726; David Spiegel, "Mind MattersGroup
Therapy and Survival in Breast Cancer," ibid., pp.
1767-1768; and Gina Kolata, "Study Rebuts Belief That Support
Groups Can Extend Life," The New York Times, December
13, 2001, p. A22.
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