Report in English with a Dutch summary (KCE reports 45A)

KCE reports vol.45 Screening for Colorectal Cancer 81
concluded that compliance was more likely with the immunochemical than the
guaiac test, independent of the test kit provider. Guaiac tests showed a higher
variability of the results among centres. This issue will be discussed in detail
further on in present report (section on screening acceptability and
compliance).
The Blue Cross and Blue Shield association assessed, in its Assessment Program
Volume 19, No. 5 July 2004 270, iFOBTs versus gFOBTs with 2 objectives: (1) to
evaluate whether there is sufficient evidence to evaluate the performance of
iFOBTs in general, or of specific iFOBTs, and to compare performance to
standard gFOBTs and (2) to examine the evidence on patient compliance with
various iFOBT formats to determine if compliance is more likely with any or
with a specific iFOBT versus gFOBTs. Seven studies met the selection
criteria 371-377. Because none of the studies enrolled an average-risk CRC
screening population all studies were assigned a quality rating of Fair. No
major flaws in any of the studies changed that rating; lesser quality items were
considered by adding a plus or minus sign to the rating. All studies calculated
performance characteristics based on one FOBT screening procedure, with
sampling according to the manufacturer s directions. No studies were designed
to estimate programmatic screening performance characteristics i.e., annual
screening over several years.
Four studies compared iFOBTs to the Hemoccult II gFOBT; 2 studies compared
iFOBTs only to Hemoccult Sensa; and 1 study compared 2 different iFOBTs
including the only published evaluation of the InSure iFOBT performance
characteristics (n = 443). The vast majority of comparative data on iFOBTs are
derived from studies of FlexSure OBT (n = 2.946) and HemeSelect (n = 1.853),
neither of which are currently available in the U.S. Only 1 included study
evaluated MonoHaem (n = 81) and none evaluated Instant-View or immoCARE.
Of interest in a colorectal cancer screening program is the yield of early stage
cancer and large adenoma. However, numbers of all cancers were low and in
several studies were less than 5; stage information was not available in every
study. For best estimates of FOBT performance characteristics, the evidence
evaluation in this assessment focussed on significant neoplasia, a combination of
cancers and large adenomas (i.e., > 1 cm).
In all but 391 patients 378, the FOBT tests compared in each study were run on
each patient and the results were matched by patient. Thus, statistical
comparisons of proportions from independent samples are inappropriate for
determining significant differences between performance characteristics such as
sensitivity and specificity. Rather, McNemar s test, which takes paired data into
account, is most often used in this situation. However, none of the included
studies presented raw data in a format that allowed McNemars test to be
conducted. Two studies compared sensitivities and specificities by McNemar s
testing and reported the results. Young et al. 377 found no significant difference in
any parameter between InSure and FlexSure OBT tests. Greenberg et al. 374
reported that sensitivity results for neoplasia by Hemoccult Sensa, FlexSure, and
HemeSelect were not significantly different from each other, but all were
significantly greater than Hemoccult II; for specificity, FlexSure OBT was
significantly lower than Hemoccult II.