Heart rate variability measurement to assess disease activity in patients with Crohn's disease, a cross-sectional study

Crohn*s disease (CD) patients typically suffer from abdominal cramps and
diarrhea due to chronic inflammation of the GI tract. Clinical disease activity
has been shown to poorly correlate with mucosal disease activity. Therefore
endoscopy is considered as a gold standard to determine disease activity in
patients with CD. However both the bowel preparation and the procedure itself
is often experienced as invasive to patients.
Consequently several biochemical markers have been studied to assess disease
activity in patients with CD over the past years. Serum markers such as ESR,
Leukocytes and CRP have been correlated with disease activity, but are not
elevated in all CD patients. More recently, faecal calprotectin was
investigated as a surrogate marker for endoscopic lesions in IBD. Both serum
and fecal markers require sampling of blood and this could also be considered
invasive in some patients.
Moreover for some of the current markers it takes relatively long to retrieve
the results from the laboratory.
Hence a non-invasive marker that correlates with mucosal disease activity and
provides a rapid result would be clinically useful in patients with CD.

The balance of the autonomic nervous system in patients with rheumatoid
arthritis and other inflammatory diseases is shifted to the sympathetic rather
than the parasympathic side. Patients with more parasympathic influence exhibit
lower inflammatory signs (C-reactive Protein (CRP), Cytokine release,
Cortisol). Moreover, the parasympathetic nerve system inhibits the production
of pro-inflammatory cytokines by activated monocytes/macrophages and thus
decreases local and systemic inflammation. These interactions are predicted by
the **cholinergic anti-inflammatory pathway**. The Heart rate variability (HRV)
has been identified to be a marker of the parasympathic activity.

We hypothesize that HRV could serve as a marker for disease activity in
patients with active or inactive Crohn*s disease (CD).
As a primary outcome, simple endoscopic score of crohn's disease (SES-CD) will
be used in comparison with HRV.

The design of the study is a single centre, non-randomised, prospective cohort
study.
The study is an observational study with a relatively little invasive
measurement.

Only patients with an existing indication for endoscopy and blood sampling will
be eligible for this study. Besides HRV, all other measurements performed in
this study are part of routine practice and will not be performed without a
clinical indication (beyond the scope of this study). Therefore HRV, a
non-invasive measurement, an EKG like device, without any potential
complications will be the only extra burden in these patients related to the
study. Participation in this study will not result in an extra hospital visit.