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. Author manuscript; available in PMC: 2014 Apr 1.
Published in final edited form as: Cancer. 2013 Jan 18;119(7):1437–1445. doi: 10.1002/cncr.27874

Table 3.

Exploratory Subgroup Analysis

Variable Control
Mean
(SD)		 Intervention
Mean
(SD)		 Difference
from
regression
(95% CI)		 P-value
from
regression
3-month
Decisional Conflict Uncertainty Scale

  1. It is clear what choice is best for me.

  2. I'm sure what to do in this decision.

  3. This decision is easy for me to make.

 Interaction
p<0.05
Physical Function <= 50, worse function 31.8
(25.0)		 27.5
(23.2)		 −4.4
(−11.2, 2.5)		 NS
Physical Function > 50, better function 20.3
(21.0)		 26.8
(22.5)		 6.2
(0.2, 12.1)		 p<0.05
3-month
Decisional Conflict Values Clarification Scale

  1. I am clear about how important the potential benefits of treatment are to me in this decision

  2. I am clear about how important the risks and side effects of treatment are to me in this decision.

  3. For the main options I am considering, I am clear about which is more important to me (the benefits or the risks)

 Interaction
p<0.05
 General Health <= 50, worse function 23.2
(17.4)		 19.3
(15.3)		 −4.2
(−8.4, −0.1)		 p<0.05
 General Health > 50, better function 17.8
(15.8)		 19.1
(15.9)		 1.5
(−3.2, 6.1)		 NS
3-month
Decisional Conflict Values Clarification Scale 		Interaction
p<0.05
 Physical Function <= 50, worse function 25.1
(17.0)		 19.3
(16.8)		 −5.8
(−10.9, −0.7)		 p<0.05
–Physical Function > 50, better function 16.8
(15.9)		 19.2
(14.1)		 2.2
(−2.6, 6.9)		 NS
3-month
Decisional Conflict Support Scale

  1. I have the right amount of support from others in making this choice

  2. I am making this choice without any pressure from others

  3. I have enough advice and information about the choices

 Interaction
p<0.01
 Physical Function <= 50, worse function 20.8
(14.4)		 16.0
(15.2)		 −4.8
(−10.1, 0.4)		 p<0.10
 Physical Function > 50, better function 13.0
(14.1)		 17.4
(14.7)		 4.1
(0.3, 8.0)		 p<0.05

The p-values related to the subgroup effects reflect the within-subgroup treatment effect. The p-values related to the interaction term reflect whether the treatment effects differ by subgroups. NS = p value > 0.10

Covariates in subgroup (interaction) regressions include patient sex, arm indicator, subgroup indicator, and the interaction term of arm indicator times subgroup indicator.