BOF: 2.60
In a prospective
epidemiological study the efficacy of 2 different chemotherapeutic agents for
carcinoma cervix were being compared. Cases were selected from one group of
patients who have had periodic PAP smears for 3 years or more prior to
diagnosis. The other group had no PAP smear history. What limitation may
result from case selection?
a) Confounding
b)
Interviewer bias
c) Berksonian
bias
d) Lead time
bias
e) Recall
bias
Answer:
d)
A more favourable response by
the first group may be attributed to the fact that they are likely to have
entered a course of treatment earlier than their counterparts. This “Lead
time” gained by the first group results in a form of non random or systematic
error which can be avoided through appropriate study design.
Author:
Dr. Sumantra Ray R.Nutr.
MBBS (Hons), DNHE, MICR
(UK), MRIPH (UK)
Clinical Research & Teaching Fellow
The Institute of Cardiovascular Research
University of Dundee Division of Medicine & Therapeutics
/ NHS Tayside
Honorary Invited Lecturer
Clinical Research Centre & Centre for Public Health
Nutrition Research
University of Dundee College of Medicine, Dentistry &
Nursing / NHS Tayside
Ninewells Hospital & Medical School
Dundee DD1 9SY
