Longitudinal Follow-up Study About Complex Regional Pain Syndrome (CRPS) Patients
Longitudinal Follow-up Study About Complex Regional Pain Syndrome (CRPS) Patients
Complex regional pain syndrome (CRPS) is a post-traumatic chronic pain condition
 characterized by pain and other symptoms typically affecting a distal limb. Relatively little
 is known about the prognosis of the course of CRPS .Currently there is no specific test to
 diagnose CRPS.

 The primary objective of the study is to investigate prospectively the evolution of CRPS and
 the impact of the psychosocial factors on health status, recovery, quality of life, and
 working status of CRPS patients.

 The secondary objective of the study is to measure blood parameters in CRPS patients to
 investigate their evolution during the course of CRPS, and maybe to identify distinctive
 biomarkers associate with CRPS and that could be potential candidate for diagnosis.
The first aim will be to monitor the evolution of the following parameters in CRPS patients:

 -  Quality of life

 -  Symptoms and signs of CRPS

 -  Severity of CRPS

 -  Working status

 -  Pain

 -  Disability

 -  Anxiety and depression

 -  Kinesiophobia

 -  Catastrophism

 -  Activity patterns with chronic pain during the two years follow-up. Every parameter will
 be evaluated with a questionnaire that allows assigning scores to each patient.

 Additionally sociodemographic data will be collected to characterize the patients (age,
 gender, marital status, educational level). The health status, treatment and medication of
 the patients will also be recorded with a medical follow-up during the two years.

 The aim is to know if the following parameters and their evolution:

 -  Sociodemographic factors,

 -  Pain,

 -  Disability,

 -  Anxiety and depression,

 -  Kinesiophobia,

 -  Catastrophism,

 -  Activity patterns with chronic pain

 are associated with the recovery, which is evaluated with

 -  Quality of life,

 -  Severity of CRPS,

 -  And working status.

 Potential associations between the different parameters will be tested (Pearson's correlation
 coefficient).

 The second aim will be to assess, in blood samples, the expression levels of specific
 molecules (miRNAs and a selection of cytokines) in patients diagnosed with acute CRPS.
 Comparison with healthy controls will be performed at the first measurement time (T0) . In a
 second time, miRNAs and cytokines profiles will be compared between acute and chronic (CRPS
 still diagnosed 6 months after the first diagnosis) CRPS patients. The measured proteins will
 include: C-reactive protein, tumor necrosis factor-alpha (TNF), interleukin-2 [IL-2], IL-6,
 IL-8, IL-10, CD40 ligand (pro- and anti-inflammatory proteins associated with pain), gene
 related peptide (CGRP), bradykinins and substance P.

 The screening, recruitment and enrolment of the patients will be done by the referring
 physician in daily clinical practice, during the consultation.

 The physician will explain to each participant the nature of the study, its purpose, the
 procedures involved, the expected duration, the potential risks and benefits and any
 discomfort it may entail. Each participant will be informed that the participation in the
 study is voluntary and that he/she may withdraw from the study at any time and that
 withdrawal of consent will not affect his/her subsequent medical assistance and treatment.

 All participants for the study will be provided with a participant information sheet,a
 consent form describing the study and providing sufficient information for participant to
 make an informed decision about their participation in the study and a prepaid envelope. Each
 patient may decide separately to participate in a) longitudinal follow-up questionnaires, b)
 blood tests or c) both parts of the study (questionnaire and blood samples). The delay for
 reflection will be 24 h. Once this period has expired, if the patient agrees to participate
 in the study, he or she is asked to return the consent form in the prepaid envelope. If he or
 she has not been send back after one week, the physician will call the patient by phone to
 make sure that it is not an omission.

 The patient information sheet and the consent form are submitted to the Ethic comitee to be
 reviewed and approved. The formal consent of a participant, using the approved consent form,
 must be obtained before the participant is submitted to any study procedure.

 The participant should read and consider the statement before signing and dating the informed
 consent form, and should be given a copy of the signed document. If the patient sent back the
 informed consent, a next appointment will be scheduled at the CRR where he or she will be
 asked to submit the signed consent form. The consent form must also be signed and dated by
 the investigator (or his designee) and it will be retained as part of the study records.

 The total duration of the project is planned over a six years period (2019-2024). The study
 will be proposed to every CRPS ambulatory patient in the CRR (2019-2022), inclusion period).
 The study will also be proposed to the patients during the last two years (2023-2024) but
 only partially, since that last questionnaires will be sent in December 2024.

 The CRPS patients are monitored on a regular and long-term basis at the CRR. The physician
 see them very regularly at the beginning (about once a month) and then the visits space a
 little out. Thus, our study fits into routine procedure and should not imply additional
 visits.

 At the first visit at the clinic, the physician will proposed the study to the patient. Upon
 acceptance, the patient will be included into the study. It consists in five measurement
 times:

 -  T0: During the days following the first visit to the clinic

 -  T1: Follow up visit 3 months later

 -  T2: Follow up visit 6 months later

 -  T3: Follow up visit 12 months later

 -  T4: Follow up visit 24 months later
Inclusion Criteria for patients:

 -  CRPS Type I (fulfilling Budapest criteria for research)

 -  Suffering of CRPS in a distal limb (hand or foot)

 -  Age >18 years

 -  Pain lasting less than 6 months

 -  Good understanding of the French language

 Inclusion criteria for control:

 -  Not suffering from chronic pain, including CRPS

 -  Age >18 years

 Exclusion Criteria for both group:

 -  Known or suspected non-compliance, drug or alcohol abuse,

 -  Inability to follow the procedures of the study, e.g. due to language problems, severe
 psychological disorders, dementia, etc

 -  For blood sample: diabetes and history of hepatitis B, C, D or HIV infection