Study of the Cognitive Effects of Chemotherapy : How Choice of Control Group Affects Outcome

The Effect of Control Group in the Study
The
Effect
of
Control
Group
in
the
Study
of the Cognitive Effects of Chemotherapy
Barbara Collins The Ottawa
Barbara
Collins
,
The
Ottawa
Hospital, Canada
ICCTF International Cognition and Cancer ICCTF International Cognition and Cancer TaskTask Force Force ConferenceConference March 15March 15--17 17 thth 2012 2012 ––PARIS PARIS --FRANCEFRANCE

Control Grou
p
s
p
Many breast cancer patients report cognitive
Many
breast
cancer
patients
report
cognitive
disturbances during and after their
chemotherapy
chemotherapy
Neuropsychological studies yield inconsistent
results
results
Cognitive effects, when found, are subtle
Detection susceptible to methodological
differences among studies
Prospective versus retrospective study design
Number and nature of cognitive tests used
ICCTF International Cognition and Cancer ICCTF International Cognition and Cancer TaskTask Force Force ConferenceConference March 15March 15--17 17 thth 2012 2012 ––PARIS PARIS --FRANCEFRANCE
Manner in which impairment is defined

Control Groups
General consensus that, in most instances,
ti l it di l t d ith
dt
prospec
ti
ve
l
ong
it
u
di
na
l
s
t
u
d
y w
ith
pre- an
d
pos
t
-
treatment testing is the preferred study design
In prospective designs, subjects serve as their
own controls
However, repeat testing associated with practice
effects
Practice effects may actually be larger than
treatment effects themselves
treatment
effects
themselves
Thus, still need to include a control group to
account for practice
ICCTF International Cognition and Cancer ICCTF International Cognition and Cancer TaskTask Force Force ConferenceConference March 15March 15--17 17 thth 2012 2012 ––PARIS PARIS --FRANCEFRANCE
account
for
practice

Control Groups
Options:
Disease-specific control group
Disease
-
nonspecific control group
Disease
nonspecific
control
group
Healthy control group
Hi t i l t l /P bli h d
Hi
s
t
or
i
ca
l
con
t
ro
l
s
/P
u
bli
s
h
e
d
norms
ICCTF International Cognition and Cancer ICCTF International Cognition and Cancer TaskTask Force Force ConferenceConference March 15March 15--17 17 thth 2012 2012 ––PARIS PARIS --FRANCEFRANCE