Biomedical Engineering Reference
In-Depth Information
participants' preferences. After that, we provide a literature review on studying
treatment effectiveness and side effects using post-marketing prescription choice
data. Lastly, we close the chapter with suggestions on future research questions, for
both practitioners and academic researchers.
6.2
Measuring Treatment Effectiveness and Side
Effects Using Clinical Trials Data
In this section, we describe the industry-wide practice of measuring treatment effec-
tiveness and safety of drugs through clinical trials. In particular, we provide a brief
overview of studies in both the pre-marketing and post-marketing period, followed
with a discussion on the statistical analysis typically performed on clinical trial data.
We also discuss its limitations and conclude that it is important to investigate the
impact of treatment effectiveness and side effects using the post-marketing pre-
scription choice data.
6.2.1
Pre-marketing and Post-marketing Clinical Trials
Clinical trials conducted before the approval of NDA are normally called pre-
marketing clinical trials, which can be further divided into three different phases.
Phase I clinical trials are the fi rst stage of testing a new drug treatment in human
subjects. The goals are to determine whether the new treatment is safe to be used by
patients, what is the best way to give the treatment (for example, through a pill or an
injection), and what is the right dose of a drug treatment—that is, the amount that
causes few side effects. This initial phase of testing, which may take several months
to complete, usually includes a small group (often 20-100) of healthy volunteers,
2
who are generally paid for participating in the study. Participants will continue to
receive the drug treatment until several half-lives of the drug have passed. They will
then take many physical exams and tests (for example, blood tests) so that doctors
can fi nd out how the treatment affects them, including how it is absorbed, metabo-
lized, and excreted. About 70 % of tested treatments
3
successfully complete Phase I
studies.
Once a new drug treatment has been confi rmed to be safe in Phase I trials, Phase
II trials are performed on larger groups (often 100 or more participants) to test
whether and how well the treatment helps patients, as well as to continue Phase
I safety assessment to test if there are any less common side effects that may appear
2
There are circumstances when some drug candidates skip Phase I and directly enter Phase II
testing. Also, in cases of terminal cancer or HIV when patients lack other treatment options,
control conditions (placebo) may not be used because it is considered ethically unjustifi able to
deny treatments to patients with life-threatening conditions.
3
We use “treatment” and “drug” interchangeably in this chapter.
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