and if so, then to suggest what its parameters
might be.
24.4 The ‘wired’ epidemiologist
It probably goes without saying in the cybernetic
environment of the twenty-first century that effec-
tive epidemiology of all types, including pharma-
coepidemiology, can only be seriously conducted
with the addition to the armamentarium of the
epidemiologist, of the skillful use of large, auto-
mated, multipurpose, population-based systems
(the LAMPS) – known by shorthand as ‘the data-
bases’. Often these databases have been developed
wholly outside the research context, with a pri-
mary intent of creating economic efficiency, qual-
ity assurance or management controls within
organized systems of healthcare. Hence, in the
United States, the organizations that construct
these databases include insurance companies, hos-
pitals, health maintenance organizations and other
companies in the healthcare business. In Canada,
and increasingly in Europe, such databases are
emerging from provincial/regional or national
reimbursement programs. If the database is
equipped with patient identifiers (e.g. a unique
membership number), then hospitalizations, pre-
scriptions and combinations of healthcare transac-
tions can be linked to a single individual across
components of the system and over time: a so-
called ‘record-linkage’ system. More recently, the
evolution of a powerful clinical management tool,
the electronic medical record, further powers the
availability of linked data for entire populations
under care. Such databases render it feasible to
assemble cohorts of drug-exposed individuals and
computer-matched comparator populations from
historical (extant) data and observe them (using
cohort analyses) forward over the time in the
database (often decades) for evidence of excesses
of events under study. Similarly, case-control
methods may assemble cases and comparators,
and use the powerful databases as the source of
the antecedent information, so elusive in hands-on
methods.
Recent regulatory efforts on behalf of the needs
to protect patient privacy have established a long
and successful record of systems that protect
patient privacy while assuring access to necessary
population-level, individual-linked data. The
recent, excellent policy positions on data privacy
protections of the American College of Epidemiol-
ogy (ACE) and the International Society for Phar-
macoepidemiology (ISPE) stand as evidence of
this competence. The reader is referred to the web-
sites of these organizations.
It is to be emphasized that such database work is
often complicated, and requires a team of profes-
sionals comprising physician and nonphysician
pharmacoepidemiologists, statisticians and specia-
lists in information technology. Perhaps one of the
greatest contributions that a clinician can make to
such a team is to provide relevance to the hypoth-
eses that are tested and as a reality check on the
results that the computers generate, and which
those less close to the field tend to regard automa-
tically as ‘fact’.
Despite the deserved enthusiasm for the contri-
bution of the LAMPS to epidemiology, more tradi-
tional hands-on, structured observational studies,
withenrollment of cohortsof persons exposed to an
agent under study and proper comparator popula-
tions, and selection of cases (e.g. from medical
records) and appropriate controls, still have speci-
fic applications in pharmaceutical medicine, thus
characterizing part of the activity of pharmacoepi-
demiologists.24.5 Definitions
The pharmaceutical physician, epidemiologist or
not, must understand the concepts of prevalence
and incidencesine qua non. Prevalenceis the
frequency of disease in a defined population, at
any one moment.Incidenceis the frequency of
new cases of a disease in a defined population
during a defined time interval.
Thus, influenza may have an incidence of 15%
for the months December–April 1999 in the
United Kingdom, whereas the prevalence of influ-
enza in the United Kingdom probably ranges
between 0 and 10% on any given day. Perinatal
(and maternal) mortality rates are usually stated
annually and for specified country or region.306 CH24 PHARMACOEPIDEMIOLOGY AND THE PHARMACEUTICAL PHYSICIAN