Biomedical Engineering Reference
In-Depth Information
and the primary goal of the NDA is to provide enough information to allow the FDA
(food and drug administration) to assess whether the new drug is safe and effective
in its proposed uses and whether the treatment effectiveness of the drug suffi ciently
outweigh the risks associated with side effects.
A standard way to compare effectiveness and severity of side effects across drugs
is through clinical trials. For example, in 2000, Bristol-Myers Squibb carried out a
clinical trial to compare the effectiveness of its cholesterol lowering drug Pravachol
against Pfi zer's Lipitor. After four and half years the median cholesterol level was
95 mg per deciliter among those who took Pravachol compared to 62 mg per deci-
liter in the Lipitor group. Another measurement showed that 26.3 % of patients in
the Pravachol group either died, suffered a heart attack, or other complications,
compared to 22.4 % of those in the Lipitor group (see Cannon et al.
2004
). Based
on these fi ndings, the researchers concluded that Lipitor provides greater protection
against death or major cardiovascular events than Pravachol does. In another exam-
ple of clinical trial, Bresalier et al. (
2005
) found from their study that patients who
used Merck & Co.'s blockbuster painkiller Vioxx had a signifi cantly higher risk of
heart attacks and strokes compared with patients in the placebo group (1.50 vs. 0.78
thrombotic events per 100 patient-year). Safety concerns were so high that in
September 2004 Vioxx was pulled out by the manufacturer from the market.
However, comparison along a single dimension does not reveal the full picture.
Although less effective in lowering cholesterol, Pravachol may have fewer or less
severe side effects than other drugs in the same therapeutic class. According to the
same study by Cannon et al. (
2004
), only 1.1 % of patients in the Pravachol group
had a higher level of enzymes that could lead to liver problems, compared with
3.3 % in the Lipitor group. Similarly, with the more severe side effect of a higher
cardiovascular risk, Vioxx was more effective in treating rheumatoid arthritis—
Bombardier et al. (
2000
) reported in their study that patients in the Vioxx group had
signifi cantly lower number of gastrointestinal and other complicated events than
patients in the group who used another existing treatment. At a 3-day hearing held
by the Food & Drug Administration in late February, 2005, even though the 32
outside experts agreed that Vioxx did pose serious risks, they also recommended
that Vioxx was useful enough that it should not be banned (Carey and Capell
2005
).
The goal of a clinical trial is to objectively measure effectiveness and side effects
of a drug. However, as illustrated in the two examples above, a more effective drug
may be associated with more severe side effects, and a safer drug may be less
effective. It is important for researchers to understand the importance of treatment
effectiveness and side effects from the physician and patient perspective. That is,
how do patients and physicians
subjectively evaluate
these treatment outcomes?
1
Without understanding such evaluations it is impossible for policy makers to deter-
mine the value of a medical treatment. The reason is obvious. For example, would
most patients rather take a more effective drug in relieving pain but with higher
1
W e d e fi ne “evaluations” as how physicians and patients are willing to trade-off between treatment
effectiveness and side effects across drugs.
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