Healthy Skepticism Library item: 20298

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Publication type: Journal Article

Lexchin J
Rethinking the numbers on adverse drug reactions
JAMC 1999 May 18; 160:(10):1432
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1232593/

Abstract:

Namrata Bains and Duncan Hunter
calculate the possible number of
deaths due to adverse drug reactions
(ADRs) by looking at the number of
hospital admissions in which an ADR
was reported and in-hospital deaths due
to ADRs. They arrive at a figure of
about 1824 deaths annually in Canada
attributable to ADRs.1
Another way to calculate this figure is
to extrapolate from data in published
Canadian studies on in-hospital ADRs.
About 15% of patients admitted to hospital
experience an ADR.2 Judging from
data from the Ontario Medical Association3
and a 5-year study of clinicopathological
examinations of surgical specimens,
4 around 1.5% of ADRs lead to
death. According to Bains and Hunter,
there are 1.3 million discharges from
Ontario hospitals each year. Using the
figures given above — that 15.0% of
these patients will have an ADR and
1.5% of those will die — 2925 such
deaths occur every year in Ontario alone.
This estimate is likely skewed to the
high side, since most ADR studies have
focused on patients on medical wards,
who tend to be sicker than those in other
areas of the hospital. At the same time, it
is also substantially higher than the one
proposed by Bains and Hunter. The difference
is probably largely due to underreporting.
Bains and Hunter acknowledge
that ADRs are underreported but
do not comment on the magnitude of
the problem. One estimate comes from a
study by Borda and colleagues.5 Although
they found 535 ADRs among 936 monitored
patients during a 3-year period,
only 350 ADRs were reported for the
other 75 373 nonmonitored patients admitted
to the rest of the hospital over the
same time. Bains and Hunter call for further
research into hospital deaths due to
ADRs based on careful analyses of routinely
collected hospital separation data,
but as long as ADRs go both unrecognized
and unreported, their approach
will consistently underestimate the true
extent of the problem.