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

KCE reports vol.45 Screening for Colorectal Cancer 121
fewer colonoscopies performed after false positive results on FOBT. Within the
ranges tested in the sensitivity analysis, the overall influence on the ICER
exerted by the sensitivity or specificity of FOBT did not exceed 1580 ($2000).
6.4 CRITICAL APPRAISAL OF THE STUDIES
In this part, we will discuss general and some specific problems with the studies
included in this overview.
Only two studies performed a cost utility analysis (Whynes, 1998, 1999; Stone).
Gyrd-Hansen and colleagues decided to ignore the impact on quality of life
(QoL) because it was judged that the main outcome of the screening program
was life years gained (Gyrd-Hansen, 1998). The most important reason not to
adjust for QoL appears to be that QoL data are not readily available. Whynes
evaluated the QoL following surgery for colorectal cancer and found that a QoL
coefficient for surviving patients lies within the range 0,948 0,981 509. These
small factors may indicate adjustment would not be expected to have a great
impact on results. However, as mentioned by Flanagan, there may also be
ethical issues related to the impact of screening on QoL. False positive FOBT
results may increase anxiety in otherwise healthy individuals. Screening may
adversely affect the QoL, given that cancers are detected earlier. Patients live
longer with knowledge of their disease and, further, the life-years gained may
not be lived in perfect health. On the other hand, the life-years gained may be
lived in less severe states of the disease. Further research to determine the
impact of mass screening on QoL is clearly necessary as these data are missing.
The majority of studies have taken the perspective of a third-party payer.
Consequently, no indirect costs such as patient time, travel costs, informal carer
costs, etc. were included. Also not included were the effects on general
consumption and productivity, which would be relevant from a societal
perspective 219. Although these costs should not be underestimated, they are
mostly omitted in studies. When included, it would be desirable to present
results separately to enhance consistency and comparability across studies.
Indirect costs may be a decisive factor if decision makers have no preference
based on other included factors.
Transparency is also an issue. Sources of cost data are often not well described.
A lack of detail on cost data means it is not always clear which costs have been
included. For example, all studies took into account the cost for FOBT.
However, it was not always clear if this was just the cost for the test kit, or if
the mailing and test analysis were also included. Or, beyond the immediate
investigation of positive FOBT results, several studies did not specify the
assumed nature or frequency of follow-up investigations.
A limitation to the majority of the studies is that they omitted program-related
expenses such as the costs of health promotion, recall systems and extra
administrative overheads (Whynes, 1998, 1999, 2004, Helm, Sonnenberg,
Frazier, Leshno, Wong, Ladabaum, Maciosek, Wu). Stone argued it was assumed
that the program was in steady-state, in order to provide estimates of ongoing
annual costs and exclude the higher implementation costs, as well as increased
detection of cancer associated with the introduction of a screening program.
However, when evaluating a mass screening campaign for colorectal cancer,
these costs are real and should be taken into account.
The disutility and potential negative health effects associated with complications
of colonoscopy were not included in about half of the studies. If the FOBT
result is positive, i.e. a false or true positive, colonoscopy test is performed.
This can, however, lead to complications such as perforation or bleedings, or