The Power of Touch. Non-Invasive C-Tactile Stimulation for Chronic Osteoarthritis Pain (TouchStim)

The Power of Touch. Randomized,Double-blind, Sham-controlled Crossover Trial of Interoceptive Non-invasive Tactile Stimulation for the Treatment of Osteoarthritis Chronic Associated Pain

Osteoarthritis (OA) is a degenerative disease with a prevalence of up to 30% among adults over 45 years old. Moreover, elderly people over 60 years are more prone to develop a chronification of pain symptomatology. Chronic pain in OA enormously restricts patients' ability to perform their daily activities, eliciting psychological distress and mood alterations, and producing massive socioeconomic consequences. For these reasons, any non-invasive drug-free treatment that decreases chronic pain in OA requires serious evaluation. This study aims to investigate the effectiveness of noninvasive interoceptive stimulation (affective touch) in treating chronic pain associated with osteoarthritis (OA). This study aims to investigate the effectiveness of noninvasive interoceptive stimulation (affective touch) in treating chronic pain associated with osteoarthritis (OA).

The current study aims to assess the long-term analgesic efficacy of interoceptive tactile stimulation in patients suffering from chronic moderate-to-severe osteoarthritis (OA) pain. The study will be a randomized, double-blind, sham-controlled crossover trial involving 60 OA patients with moderate-to-severe chronic pain. Patients will be randomly assigned to the treatment or control group and received interoceptive (affective touch) or control stimulation two days a week for 12 weeks. Patient will then undergo to a 4-week washout period, after that they will be assigned to the crossover treatment for another 12 weeks. The study will measure changes in pain and physical function, heart rate variability, as well as inflammatory and anti-inflammatory cytokines and medication intake, assessed at baseline, and at the end of each crossover phase. Follow-up measures will be assessed 4 weeks after the end of each crossover phase. Intermediate outcomes for pain and physical function, heart rate variability and medication intake will also be assessed after 4 and 8 weeks.

Participants will receive General Practitioner (GP) care and interoceptive non-invasive tactile stimulation (affective touch) for 30 min two times a week for 12 weeks.

Participants will receive General Practitioner (GP) care and a sham stimulation for 30 min two times a week for 12 weeks.

The intervention is a non-invasive interoceptive stimulation (affective touch) delivered to the left volar forearm. The stimulation is delivered using a device with a small tactile probe that touches the skin in a circular motion. The device is designed to induce maximum firing frequency in the peripheral C-Ts nervous afferents, which respond to low-force, low-velocity stimuli, specifically 3 cm/sec, 2.5mN. The stimulation will be delivered in 18 blocks, each consisting of 6 short periods of stimulation of varying durations presented in random order, with pauses of 6 seconds after every single stimulation, the entire stimulation protocol will have a total duration of 30 minutes.

In the sham condition, patients will receive a similar stimulation with the interoceptive tactile device, however, the device will be turned on for only 3 seconds every minute, and consequently turned off for 57 seconds. The entire duration of the stimulation will be approximately 30 minutes, similar to the experimental condition.

A higher WOMAC score represented worse symptom severity. Measures are assessed in a modified intention-to treat population for all participants randomly assigned to groups and who attended a baseline visit.

the physical function subscale scores of the Western Ontario and McMaster Universities OA Index (WOMAC)

A higher WOMAC score represented worse symptom severity. Measures are assessed in a modified intention-to treat population for all participants randomly assigned to groups and who attended a baseline visit.

Will be the change from baseline to week 12 in the physical function subscale scores of the Western Ontario and McMaster Universities OA Index (WOMAC).

Measures are assessed in a modified intention-to treat population for all participants randomly assigned to groups and who attended a baseline visit.

Interleukin-10 (IL-10), Tumor necrosis factor alpha or TNF-α, interleukin 1 family of cytokine, IL-1β, Interleukin-6 (IL-6), Interleukin-4 (IL4)

Pain Numeric Rating Scale (NRS). Minimum score 0 (no pain); maximum score 10 (worst pain imaginable). The higher the score the higher the pain.

Interleukin-10 (IL-10), Tumor necrosis factor alpha or TNF-α, interleukin 1 family of cytokine or IL-1β, Interleukin-6(IL-6),Interleukin-4 (IL4), cortisol and oxytocin

the percentage of patients who responded to treatment according to ≥30% and ≥50% changes at week 12 in the WOMAC pain and physical function subscale scores.

Pain weekly measures will be collected with a pain diary two days a week. In the dairy, patients will report pain ratings on the WOMAC pain subscale, to keep track of sudden variations in the symptomatology (i.e., flares) in the 48 hours preceding the treatment sessions.

Inclusion Criteria: osteoarthritis patients Age 45-90 Diagnosis of OA ACR criteria Moderate-to-severe OA chronic pain. Exclusion Criteria: other joint diseases trauma, or pain condition fibromyalgia BMI>39 kg/m2.