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tuberculosis nos
lupus-like syndrome
systemic lupus erythematosus
disseminated tuberculosis
pulmonary tuberculosis
medication error
0.01
0.10
1.00
10.00
Reporting Ratio
Fig. 15.2. Adverse event plot for the drug infliximab with the point sizes proportional to the suspect
fraction
S
ab
.
observations suggest a greater agreement between the objective and subjective
measures of association for fluoxetine than for infliximab.
15.4. Case-Specific Associations
The objective association measures
R
ab
and
U
ab
defined and discussed in Sec.
15.2 are aggregate measures, based on the entire dataset. In addition, it is possi-
ble to define two other
case-specific association measures
that are also objective
measures of the relationship between Drug A and Adverse Event B, but which are
based only on records lising the drug and the adverse event together. As noted in
Sec. 15.1, a typical ISR lists several drugs and several adverse events, and in these
ISR's, one drug is always specified as primary suspect. In ISR's that list only a sin-
gle drug, a situation called a
pure play
in the pharmacovigilance community, that
drug is necessarily the primary suspect. This observation motivates the following
definition: the
pure play fraction
ψ
ab
is the fraction of ISR's listing both Drug
A and Adverse Event B that are pure plays (i.e., that list Drug A alone). It fol-
lows from this definition that
ψ
ab
≤
S
ab
, establishing a relationship between this
objective association measure and the subjective association measure discussed
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