What problems might you encounter?
You answered:
Patients
who have already tried amitriptyline and found it ineffective
may be unwilling to try it again, reducing enrollment
and potentially biasing the results in the amitriptyline
group towards a positive response.
EITHER
A OR B MAY BE CORRECT
- Withdrawing
patients from effective treatment and forcing them
to try a treatment that they previously thought was
ineffective may both reduce enrollment and bias the
results in an unforeseen direction, depending upon
the choices that patients make.
- Allowing
patients to continue other medications that do not
have a strong and obvious interaction with the study
drug (or the neurochemical systems it influences)
will improve enrollment. This is the choice I most
commonly make. Hazards include unforeseen interactions
with study drugs and increased variability in outcomes.
- Recruiting
patients on first diagnosis, before they have been
exposed to standard treatments, is a third option.
However, such patients may be hard to find; and patients
and research review committees may insist on a trial
of proven therapy first.