Biomedical Engineering Reference
In-Depth Information
specification, physician
i
i's number of prescriptions of the focal drug are a function
of time dummies d, marketing variables
x
(including detailing and sampling),
physician
j
's current and lagged prescriptions
y
t
and
y
t
−1
, prescriptions of all other
physicians
y
other
, and control variable
z
. Here
z
are the mean number of prescriptions
issued by the other physicians in the same zip-code as physician
i
(and
j
) but not in
the sample.
i
y
=+ +
aa aa aa a
-
d
x
+
z
+
y
+
y
+
y
+
a
y
it
+
e
(15.4)
it
i
1
t
2
it
3
sample
,
t
4
jt
5
other
_ ,
it
6
jt
-
1
7
-
1
it
The corresponding specification for
j
is number of prescriptions issued is
j
y
=+ +
bb b
d
x
+
b
z
+
b
y
+
b
y
+
b
y
+
b
y
jt
+
e
jt
(15.5)
jt
j
1
t
2
jt
3
-
sample
,
t
4
it
5
other
_ ,
jt
6
it
-
1
7
-
1
In this specification,
a
4
and
b
4
are the key parameters that measure the peer effect.
BW estimate a simultaneous equations model on these three types of movements
and find that the specialist has a significantly positive effect on the PCP but not vice
versa suggesting an opinion leader effect. BW compute the social multipliers for
these opinion leaders which range from 1.16 to 1.83, much higher than those
computed by NMB. BW attribute these to the nature of the identification process
where the surveys do “not reveal all of the physicians influenced by a particular
physician but only a subset of them.” A regression of the social multipliers on
specialty categories, the number of physicians in each zip-code, and the category
prescription deciles find focal specialists who are high prescribers are more likely to
be opinion leaders.
15.4
Managerial Implications
There is a high economic benefit to pharmaceutical firms in identifying opinion
leaders and physician networks of influence. First and foremost, these opinion
leaders are very influential to the success or failure of any new therapy, new drug
launch, or new medical device use. There are two ways in which opinion leaders
can ensure quick product uptake in a new drug or medical device launch. First, the
opinion leaders can act as spokespeople spreading the word about the better effi-
cacy and/or beneficial side effect profile of the new pharmaceutical drug or medi-
cal device. These opinion leaders drive the word-of-mouth for the new drug or
medical device, creating a cascading effect, helping it gain the critical mass of
patients required to lead that drug over the “tipping point” to make it a commer-
cial success. Pharmaceutical firms actively engage key opinion leaders in clinical
trials and as speakers in various industry conferences in order to influence other
physicians to follow the lead of these opinion leaders in adopting and using the
new drug or medical device. Iyengar et al. (
2011
) find that the time of adoption by
influenced physicians goes down as a result of opinion leader adoption. Second,
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