Systemic sclerosis (SSc), also known as systemic scleroderma, is a chronic autoimmune disease of the connective tissue. In healthy individuals, the immune system produces antibodies (proteins that recognize and destroy specific substances) to attack foreign invaders, such as bacteria and viruses. In those affected by autoimmune diseases, the body produces antibodies against its own tissues. For patients with SSc, antibodies attack its own connective tissue.
SSc is characterized by the thickening of the skin due to buildup of collagen and injuries to small arteries. Systemic Sclerosis is categorized into two forms, limited systemic sclerosis and diffuse systemic sclerosis. Limited systemic sclerosis refers to systemic sclerosis that only affects the face, hands and feet. Diffuse systemic sclerosis affects more of the skin and may progress to visceral organs, such as the kidneys, heart, lungs and gastrointestinal tract.
Signs and symptoms of the disease include hardening and scarring of the skin, muscle weakening, recurrent itching and Raynaud’s phenomenon. Raynaud’s phenomenon (RP) is the excessive reduction of blood flow in response to emotional stress or cold, causing discoloration of the fingers and toes. This phenomenon is thought to be caused by a hyperactive sympathetic nervous system, resulting in extreme constriction of blood vessels.
Since microvascular abnormalities play such a large role in the pathogenesis of SSc, it’s important to analyze the severity of these abnormalities. Nailfold capillaroscopy (NC) offers the best method to do this. Disorganization of blood vessels, giant capillaries, hemorrhages, loss of capillaries, angiogenesis (development of new blood vessels) and avascular areas often characterize SSc.
The survival rate of patients with SSc has improved over the past two decades, but SSc can still cause increased disability and decreased quality of life. SSc may affect the hands, tendons and joints, leading to significant functional disability.
Past research has suggested that low vitamin D levels are highly prevalent in patients with SSc. However, no studies have been conducted regarding the relationship between vitamin D levels and quality of life among SSc patients. Therefore, a recent study aimed to determine the association between vitamin D and quality of life, clinical parameters and NC in patients with diffuse SSc.
The researchers assessed the vitamin D levels of 38 female patients with diffuse SSc. They measured autoantibodies, the antibodies produced to target body’s own tissues. Medsger Disease Severity Index (MDSI) determined the severity of SSc. Health Assessment Questionnaire (HAQ) assessed the difficulty of activity, including dressing, eating, walking, personal hygiene, reach, grip strength and usual daily activities. The Short Form Questionnaire (SF-36) measured physical functioning, pain, vitality, social function, emotional role and mental health. Clinical data was gathered through an interview and a review of the electronic register database. Lastly, NC was performed to examine the microvascular abnormalities.
Here is what the researchers found:
- Average vitamin D levels were 20.66 ng/ml.
- Interstitial lung disease (79%), esophageal hypomotility (63%), digital ulcers (63%) and joint involvement (55%) were the most prevalent clinical manifestations.
- There was no relationship between vitamin D and any of the most prevalent clinical manifestations.
- Osteoporosis was found in 37% of the patients.
- Vitamin D status was positively correlated with total femur bone mineral density, femoral neck bone mineral density and fat mass (p = 0.038, 0.017, 0.048, respectively).
- No relationship was observed between vitamin D status and MDSI.
- Low vitamin D status was associated with severe NC alterations (p < 0.05).
- Low vitamin D levels related to poorer scores on the SF-36-Vitality, SF-36-Social Function, SF-36-Mental Health, SF-Emotional Role (p = 0.017, 0.050, 0.0006, 0.049).
- Low vitamin D levels were associated with poorer scores on HAQ-Reach and HAQ-Grip Strength (p = 0.044, 0.042, respectively).
- The presence of SSc-specific autoantibody levels was correlated with low vitamin D levels (p = 0.039).
The researchers concluded,
“The present study provides novel evidence demonstrating that low levels of 25OHD can contribute to a decreased QoL in patients with diffuse SSc through its association with the underlying vascular involvement (worst capillaroscopic findings) and the autoantibody production (anti-Scl70).”
It’s important to note a few of the study’s limitations. As this study followed a cross-sectional design, this provides merely the jumping off point for research on vitamin D and quality of life in SSc patients. The study shows only association, which is important to distinguish from causation. Lastly, the sample size was relatively small and only consisted of African American women. Larger studies using both men and women are needed for further investigation.
Although more research is needed to determine whether vitamin D definitively plays a role in SSc, patients with SSc who take 5,000 IU of vitamin D have nothing to lose.
Tovey, A & Cannell, JJ. New study finds low vitamin D status is associated with reduced quality of life among diffuse systemic sclerosis patients. The Vitamin D Council Blog & Newsletter, 2016.