Central Sensitisation and Functioning in patients with Chronic Low Back Pain

Functioning is often limited in patients with chronic low back pain (CLBP),
which has a negative effect on participation. Limited functioning is one of the
main reasons to refer patients for pain rehabilitation. Until now, there is
limited evidence to explain the limited functioning, despite of hundreds of
studies that have investigated biological, psychological en social variables.
One of the few variables that is consistently related to functioning, although
to a moderate extend, is pain intensity . In the past decennia there is
growing evidence for sensitisation in (a relevant subsample of) patients with
chronic pain. Theoretically, sensitisation can be plausible linked to pain
intensity and to functioning. Some evidence is found for the relation between
sensitisation and intensity of pain, but not with functioning.
Sensitisation and functioning can be operationalized and measured in different
ways:
Sensitisation can be measured with a standardized protocol called Quantitative
Sensory Testing* (QST) . This examination must be performed by a trained
professional and takes 30-60 minutes. Another way to measure sensitisation is
by means of a questionnaire called *Central Sensitisation Inventory * (CSI; 25
questions, 5 minutes), and the measurement of *heart rate variability* (HRV; 5
minutes). The relationship between these measures is unknown yet.
Functioning can be measured by means of capacity testing (aerobic capacity,
lifting capacity), performance testing (accelerometry), or a questionnaire
(RAND Physical Functioning [PF], Pain Disability Index [PDI], Work Ability
Index [WAI]). The relationship between sensitisation and functioning is
unknown. It is also unknown if a decrease in sensitisation is related to
improved functioning.

The overarching aim of this project is to study the relation between
sensitisation and functioning in patients with CLBP.

The project consists of 3 studies, each with a different main objective.
1. To analyse the association between instruments measuring sensitisation in
patients with CLBP.
2. To analyse the association between sensitisation and functioning in patients
with CLBP.
3. To analyse whether a decrease in sensitisation is related to improved
functioning in patients with CLBP.

Study 1 and 2: Cross sectional. Measurements during admission phase of
rehabilitation.
Study 3: prospective. Measurements during discharge phase of rehabilitation.

Burden and risk:
Patients will scheduled for a separate 1 hour appointment to complete all
additional assessments (at baseline and at discharge; additional to care as
usual). If possible, this will be adjacent to a care as usual appointment.

Exrta tests * burden and risks:
* QST: 30 minutes. No risks.
* HRV: 5-10 minutes. No risks.
* Accelerometry: 1 week continuous wearing of an accelerometer to measure daily
movements. A small device will be worn on the trouser belt. No risks.

Benefit:
Patients will be informed about the results of the assessments. No direct
benefits on their health status.
Patients will receive compensation for extra travel costs (¤0.19/km) and a
gift check of ¤10 when both assessments are completed.