Background
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As early as 1965, L.J. Witts wrote that ‘the final test of the safety of a drug is in fact its release for general use’.
PEM in the UK
BACKGROUND
As
early as 1965, L.J. Witts wrote that ‘the final test of the safety of a drug is
in fact its release for general use’. The recognition that not all hazards
could be known before a drug was marketed and that spontaneous adverse drug
reaction reporting systems may fail to identify all hazards led to several
proposals for schemes based on the identification of patients by means of
prescription data. These schemes were largely intended to provide information
on populations of known size so that the incidence of adverse reactions could
be estimated with reason-able accuracy. The proposals included ‘Recorded
Release’, Registered Release’, ‘Retrospective Assess-ment of Drug Safety’ and a
number of variants (Inman, 1978a).
One
of the limitations of spontaneous reporting is that doctors may fail to
identify and report illnesses which they do not suspect to be due to a drug.
This realisation led to the development of systems based upon ‘event’ reporting
in which the doctor did not need to diagnose or suspect the true cause but was
asked merely to record events. To this thinking the distinguished statistician,
D.J. Finney, made a funda-mental contribution in a paper in 1965 in which an
event was defined as ‘a particular untoward happening experienced by a patient,
undesirable either generally or in the context of his disease’ (Finney, 1965).
These
ideas – published only 4 years after the orig-inal announcements of Lenz
regarding thalidomide and congenital abnormalities (Lenz, 1961, 1962) – came
together in the founding by W.H.W. Inman of prescription–event monitoring
(PEM). The establish-ment of PEM at the University of Southampton in 1980 and
Inman’s early experience with this technique have been recorded in publications
(Inman, 1981a,b; Inman, Rawson and Wilton, 1981) which established that the key
objective was to recruit the first 10 000 patients who received a new drug of
interest so that any adverse event that occurred in more than one in 1000
patients would be reliably identified.
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