Cost-Effectiveness of a diagnostic Decision rule for patients with lower Abdominal complaints in primary caRe.

Lower gastro-intestinal (GI) tract complaints are frequently presented in
primary care. About 7% of these patients has organic bowel disease (OBD), such
as Inflammatory Bowel Disease or Colorectal Cancer. Most have functional
disease (FBD), such as Irritable Bowel Syndrome. Adequate discrimination is
important, as both unnecessary endoscopy as well as delayed detection of OBD is
burdening and costly. Presently up to 20% of patients with persisting GI
complaints is referred for endoscopy, but only in one-third OBD is found. The
diagnostic process in primary care needs improvement. Symptoms alone cannot
identify OBD accurately, but new point-of-care faecal biomarker tests for
inflammation are promising. This study aims to identify the most cost-effective
diagnostic strategy to estimate the absence or presence of OBD in patients with
lower intestinal complaints, combining history, physical examination, blood
tests, an immunochemical fecal occult blood test and a faecal calprotectine
test.

The aim of the study is to quantify the accuracy and cost-effectiveness of a
diagnostic decision rule for OBD, in patients with persisting lower
gastro-intestinal complaints in primary care.

This diagnostic cohort study in primary care includes all patients with lower
GI tract complaints longer than 2 weeks, in whom referral for endoscopy is
indicated because of increased risk of OBD. All patients undergo history taking
and physical examination. In addition biochemical parameters (ESR, CRP, Hb,
leucocytes and anti-tTG antibodies), an immunochemical fecal occult blood test
and a point-of-care calprotectine test are determined. Patients will be
referred for endoscopy. After the endoscopy, subjects will be asked to fill out
the three questionnaires once more for follow-up and the results of the
endoscopy will be obtained.
Participation of 110 practices is required to include 990 patients referred for
lower intestinal endoscopy, of whom 300 patients will have OBD.The project will
require 36 months (3 months for preparation and recruitment of practices, 30
months for inclusion and follow-up and 3 months for data-analysis and reporting
results).

Beside the usual care -conform existing guidelines- of history taking and
physical examination, the burden of patients for participation notably exists
in answering additional questions about their complaints and quality of life
(twice), a blood sample and collecting a fecal sample prior to the endoscopy.
The study has no influence on the diagnostic or therapeutic strategy of the
practising physician.