Vagus Nerve Stimulation for Systemic Lupus Erythematous

Questionnaire on autonomic symptoms: Composite Autonomic Symptoms Score 31 (COMPASS-31)

The COMPASS-31 is a validated questionnaire of 31 questions providing a quantitative measure of autonomic nervous system dysfunction symptoms. The score ranges from 0 (no symptoms) to 100 (most severe autonomic symptoms).

Time frame: During period 1: At baseline and follow-up (day 7). During period 2: At baseline, at day 7-visit and at follow-up (week 8).

Questionnaire on SLE disease activity: Patient Global Assessment (PtGA)

The participants rate their subjectively perceived disease activity on a scale from 0 to 10, in which 0 = no disease activity and 10 = worst imaginable disease activity.

Time frame: During period 1: At baseline and follow-up (day 7). During period 2: At baseline, at day 7-visit, weekly (week 3-7) until- and at follow-up (week 8).

Questionnaire on SLE disease activity: Systemic Lupus Activity Questionnaire (SLAQ)

In the SLAQ the participants rate their perceived disease activity by rating the severity of 24 disease activity related symptoms by either "no problem", "mild", "moderate" or "severe" In the SLAQ the participants rate their perceived disease activity by rating the severity of 24 disease activity related symptoms by either "no problem", "mild", "moderate" or "severe" and a Patient Global Disease Activity measure as mentioned in (3).

Time frame: During period 1: At baseline and follow-up (day 7). During period 2: At baseline, at day 7-visit, and at follow-up (week 8).

Questionnaire on quality of life: Short form-12 (SF-12)

From the validated 12-item SF-12 a physical and mental component score of patient-reported health related quality of life is calculated. Component scores range from 0-100 (lowest to highest level of self-reported health) and are calculated by giving specific weights to each of the 12 individual items/questions, calculating a weighted sum, and finally adding the sum to a component specific constant.

Time frame: During period 1: At baseline and follow-up (day 7). During period 2: At baseline, at day 7-visit, and at follow-up (week 8).

Questionnaire on pain: Visual analog rating scale (VAS)

Participants will assess the level of musculoskeletal pain within the previous 7 days by scoring the level on the VAS (0 to 10, where 0 = no pain and 10 = worst imaginable pain).

Time frame: During period 1: At baseline and follow-up (day 7). During period 2: At baseline, at day 7-visit, weekly (week 3-7) until- and at follow-up (week 8).

SLE disease activity: SLE Disease Activity Index 2000 (SLEDAI-2K)

The validated SLEDAI-2K entails 24 weighted descriptors of disease activity across 9 organ systems. The SLEDAI-2K-score ranges from 0 (no activity) to a theoretical maximum score of 105 and reports on manifestations occurring up to 10 days before the examination.

Time frame: During period 1: At baseline and follow-up (day 7). During period 2: At baseline, at day 7-visit and at follow-up (week 8).

SLE disease activity: SLEDAI Responder Index 50% (SRI-50)

The SRI-50 is a validated derivation of SLEDAI-2K that considers clinically significant improvements (≥ 50%) between visits.

Time frame: During period 1: At baseline and follow-up (day 7). During period 2: At baseline, at day 7-visit and at follow-up (week 8).

SLE disease activity: SLE Disease Activity Score (SLE-DAS)

The SLE-DAS is a validated index containing 17 clinical and laboratory descriptors and is a global measure of SLE disease activity suggested to have improved sensitivity to change and specificity as compared with the SLEDAI-2K.

Time frame: During period 1: At baseline and follow-up (day 7). During period 2: At baseline, at day 7-visit and at follow-up (week 8).

SLE disease activity: Physician Global Assessment (PGA)

The PGA measures disease activity in SLE is determined by the physician's judgement of overall disease activity. It is scored by answering "How do you rate your patient's current disease activity?" with 1=mild, 2=moderate or 3=most active disease imaginable.

Time frame: During period 1: At baseline and follow-up (day 7). During period 2: At baseline, at day 7-visit and at follow-up (week 8).

SLE disease activity: Painful and swollen joints

The number of painful and swollen joints are assessed according to the Disease Activity Score-28 (Swollen joints: 0 = no, and 28 = 28 swollen. Painful joints: 0 = n, and 28 = 28 painful joints).

Time frame: During period 1: At baseline and follow-up (day 7). During period 2: At baseline, at day 7-visit and at follow-up (week 8).

Autonomic function: Resting heart rate variability (HRV)

With the VagusTM device, 5 minutes of resting HRV is measured. Classical time (SDNN, RMSSD) and frequency (LF, HF, total and LF/HF) domain heart rate variability parameters will be assessed.

Time frame: During period 1: At baseline and follow-up (day 7). During period 2: At baseline, at day 7-visit and at follow-up (week 8).

Autonomic function: Resting Cardiac Vagal Tone (CVT)

Cardiac vagal tone reflecting parasympathetic activity is measured through three chest electrocardiography electrodes. A cardiac monitor, the eMotion Faros device is attached to the electrodes and the electrocardiogram is sampled at 8 kHz for 5 minutes, from which the cardiac vagal tone is derived.

Time frame: During period 1: At baseline and follow-up (day 7). During period 2: At baseline, at day 7-visit and at follow-up (week 8).

Autonomic function: Cardiovascular autonomic reflex tests - heart rate response

The heart rate response to three cardiovascular autonomic reflex tests are assessed with the VagusTM-device for estimation of the degree of autonomic dysfunction: The ratio of the maximum and minimum heart rate in relation to a) standing, b) deep breathing and, c) a Valsalva maneuver. By comparing results of the cardiovascular reflex tests with age-dependent cut-off levels, the degree of autonomic dysfunction is divided into categories: no, early (one) and manifest (two or three abnormal tests).

Time frame: During period 1: At baseline and follow-up (day 7). During period 2: At baseline, at day 7-visit and at follow-up (week 8).

Autonomic function: Cardiovascular autonomic reflex tests - blood pressure response

The blood pressure response to one cardiovascular autonomic reflex test is assessed. After a supine 5-min rest, the orthostatic blood pressure is measured. The participant stands for 5 minutes while the blood pressure is measured each minute. Blood pressure drops (systolic 20 mmHg or diastolic 10 mmHg) indicate impaired, especially, sympathetic function.

Time frame: During period 1: At baseline and follow-up (day 7). During period 2: At baseline, at day 7-visit and at follow-up (week 8).

Autonomic function: Continuous heart rate and HRV monitoring

A small patch sensor (ePatch) will be used to monitor the heart rate variability during a period of 7 days. Classical time (RR-interval, SDNN, SDNNi, SDANN, RMSSD) and frequency (VLF, LF, HF and LF/HF) domain heart rate variability parameters will be assessed.

Time frame: During period 1: From baseline to follow-up (day 7). During period 2: From baseline to day 7-visit.

Autonomic function: Sweat secretion

The Sudoscan® provides a quick, non-invasive and reproducible assessment of sympathetically controlled sudomotor function, and is based on a reaction between electrodes and chloride ions after a low-voltage sweat gland stimulation as the patient is situated with their hands and feet on two different measure pads for 3 minutes.

Time frame: During period 1: At baseline and follow-up (day 7). During period 2: At baseline, at day 7-visit and at follow-up (week 8).

Pain tolerability: Cold pressor test

The left hand is immersed in circulated ice-chilled water (2.0°C). The subject will be instructed to tolerate to hold the hand in the water for up to 120 seconds or when intolerable pain is reached. At different timepoints throughout the stimulation, the participants are asked to rate the sensation on a numerical rating scale from 0 to 10, where 0 = no pain and 10 = worst pain.

Time frame: During period 1: At baseline and follow-up (day 7). During period 2: At baseline, at day 7-visit and at follow-up (week 8).

Pain tolerability: Conditioned pain modulation (CMP)

The CPM-capacity response can be quantified by applying a "test-pain" (muscle pressure on right quadriceps) before and after the conditioning stimulus. The difference in pressure stimulus intensity before, during, and after induction of cold pressor pain provides a quantitative index of CPM capacity in the individual participant. The techniques used for pressure stimulation and cold pressor test described above will be combined to measure CPM.

Time frame: During period 1: At baseline and follow-up (day 7). During period 2: At baseline, at day 7-visit and at follow-up (week 8).

Cardiac function

Cardiac function is assessed with echocardiography, which is a non-invasive ultrasound examination elapsing from 15 -30 minutes, performed with the patient in supine position. A transducer is run across the thorax for visualization of cardiac diastolic and systolic function, anatomical structures, arterial stiffness as well as muscle and chamber sizes to describe systolic and diastolic cardiac function.

Time frame: During period 1: At baseline and follow-up (day 7). During period 2: At baseline, at day 7-visit and at follow-up (week 8).

Vascular function: Microvascular function

Nailfold video capillaroscopy is a non-invasive diagnostic technique that evaluates the morphology of the capillaries in the nailfold through direct visualization. It can reveal both the architecture of capillary rows and fine details of each vessel.

Time frame: During period 1: At baseline and follow-up (day 7). During period 2: At baseline, at day 7-visit and at follow-up (week 8).

SLE routine status

SLE clinical status is assessed by performing routine blood-based analyses of hematological, serological and urinary markers for different organ-specific and SLE-specific characteristics.

Time frame: During period 1: At baseline and follow-up (day 7). During period 2: At baseline, at day 7-visit and at follow-up (week 8).

SLE inflammatory status - Multiplex plasma cytokine analysis

SLE inflammatory status is assessed by analyzing the blood plasma for especially activation markers: TNF, IL-1b, sIL-2Ra, IL-6, IL-8, IL-17, IFN-g, IFN-alfa and Inhibition markers: sTNFr, IL-1RA, IL-10, TGF-b.

Time frame: During period 1: At baseline and follow-up (day 7). During period 2: At baseline, at day 7-visit and at follow-up (week 8).

SLE inflammatory status - Interferon-regulated gene expression

SLE inflammatory status is assessed by analyzing interferon-regulated gene expression in whole blood (nCounter platform, NanoString Technologies, Seattle, WA).

Time frame: During period 1: At baseline and follow-up (day 7). During period 2: At baseline, at day 7-visit and at follow-up (week 8).

SLE inflammatory status - Immune cell population distribution in whole blood

SLE inflammatory status is assessed by analyzing the immune cell population distribution in whole blood (fluorescence-activated cell sorting).

Time frame: During period 1: At baseline and follow-up (day 7). During period 2: At baseline, at day 7-visit and at follow-up (week 8).

SLE inflammatory status - Functional immune cell stimulation

SLE inflammatory status is assessed by analyzing immune cell stimulation in whole blood (TruCulture).

Time frame: During period 1: At baseline and follow-up (day 7). During period 2: At baseline, at day 7-visit and at follow-up (week 8).

Kidney function

Kidney function is assessed by analyzing urine (3\*24 hours) for kidney specific markers such as urine albumin- and protein/creatinine-ratio.

Time frame: During period 1: At baseline and follow-up (day 7). During period 2: At baseline, at day 7-visit and at follow-up (week 8).

Metabolic control

Metabolic control is assessed at the hospital by analyzing blood plasma for lipid and glucose profiles

Time frame: During period 1: At baseline and follow-up (day 7). During period 2: At baseline, at day 7-visit and at follow-up (week 8).

Medication usage

Changes in medication status within the time frame of the study and 3 months after study completion is recorded by accessing the participants medication file.

Time frame: Medication status is reported at all visits (period 1: baseline and follow-up (day 7); period 2: baseline, day 7 and follow-up (week 8)) and three months after completing the study