Since lesions can only be detected if follow-up colonoscopy is performed, the definitions below take
into account whether or not follow-up CS was actually performed. Other positive predictive values can
be calculated, such as the PPV of the positive test without any further adjustment. In this case, the
denominator would be the number of people presenting with a positive test result leading to referral
for colonoscopy.
PPV for detection of lesions
The positive predictive value (PPV) for detection
of a lesion through an FOBT screening programme
is defined as the percentage of people with
detection of at least one lesion at follow-up CS
among those with positive FOBT tests who have
attended follow-up CS.
N people with at least one detected lesion
during the time frame *
N people positive to FOBT having attended a
colonoscopy during the time frame*
* equal to the defined screening interval or
reporting period
PPV for detection of adenoma
The positive predictive value for detection of an
adenoma through an FOBT screening programme
is defined as the percentage of people with
detection of at least one adenoma at follow-up CS
among those with positive FOBT tests who have
attended follow-up CS.
N people with at least one detected
adenoma during time frame*
N people positive to FOBT having attended a
colonoscopy during the time frame*
* equal to the defined screening interval or
reporting period
PPV for detection of advanced adenoma
The positive predictive value for detection of an
advanced adenoma through an FOBT screening
programme is defined as the percentage of people
with detection of at least one advanced adenoma
at follow-up CS among those with positive
FOBT tests who have attended follow-up CS.
Values varied between 14.6% and 54.5% in the
RCTs using only gFOBT without rehydration and
from 6.0% to 11.0% with rehydration.
N people with at least one detected
advanced adenoma advanced adenoma
during time frame*
N people positive to FOBT having attended a
colonoscopy during the time frame*
* equal to the defined screening interval or
reporting period
PPV for detection of cancer
The positive predictive value for detection of a
cancer through an FOBT screening programme is
defined as the percentage of people with
detection of at least one cancer at follow-up CS
among those with positive FOBT tests who have
attended follow-up CS. Values varied between
5.2% and 18.7% in the RCTs without rehydration
and from 4.5% to 8.6% in the initial round of
population-based programmes (5.3% to 10.6% in
subsequent screening)
N people with at least one detected cancer
during time frame*
N people positive to FOBT having attended a
colonoscopy during the time frame*
* equal to the defined screening interval or
reporting period
Endoscopic complications in FOBT screening programme
For any complication the rate is defined as the
proportion of participants presenting with a complication
among those having attended a colonoscopy
during the respective time frame. The rate
should be calculated in total and separately for
screening and follow-up colonoscopy if applicable.
N people presenting with complication
during the time frame*
N people having attended a colonoscopy
during the time frame *
* equal to the defined screening interval or
reporting period
No comments:
Post a Comment