A recent study published by The Journal of Clinical Rheumatology shows that vitamin D status is related to disease activity and quality of life in patients with rheumatoid arthritis.
Rheumatoid arthritis (RA) is an autoimmune condition resulting in chronic inflammation of the small joints in the hands and feet. This inflammation causes painful swelling that can ultimately lead to joint deformity.
Some of the symptoms patients may experience include chronic pain, muscle weakness, and mood disorders. These symptoms can greatly affect an RA patient’s quality of life, which refers to a general sense of well being and ability to enjoy normal life activities.
Current evidence supports a strong relationship between vitamin D deficiency and RA. Research not only shows that vitamin D deficiency is associated with RA, but that it may also be related to RA disease activity.
Although a multitude of observational studies have been produced supporting the relationship between vitamin D status and quality of life, as well as vitamin D status and RA, no studies have looked at all of these factors at once.
In a recent study conducted by the Military Institute of Medicine in Warsaw, Poland, researchers examined the relationship between vitamin D status and quality of life (QoL), physical activity (PA), and disease activity in individuals with RA.
The researchers enrolled 97 participants with RA and 28 patients with osteoarthritis (OA) to serve as the control group. OA is a condition that results from normal wear and tear on the joints. OA is unlike RA in that OA is not immune mediated, nor does it involve gross swelling of the lining of the joints. None of the participants supplemented with vitamin D prior to the study.
The researchers measured the participants’ serum vitamin D, calcium, phosphorous, and parathyroid hormone (PTH) levels. The participants filled out a Beck Depression Inventory questionnaire, a form that assesses severity of depression. The participants also completed a health assessment questionnaire and a SF-36 form. The health assessment questionnaire is a self-reported instrument to determine the influences of chronic illnesses on an individual’s health related quality of life. The SF-36 is another tool used to determine general health and pain severity.
The patient’s disease activity was measured by the use of Disease Activity Score 28 (DAS28), which is a common tool used in clinical trials to indicate RA improvement and disease progression.
Did the researchers find a relationship between disease activity, QoL, or PA, and vitamin D status? Here is what they found:
- Over 76% of participants with RA were also vitamin D deficient (less than 20 ng/ml), with 38% of them categorized as deeply deficient (less than 10 ng/ml).
- There was no significant difference in vitamin D status between participants with RA and those with OA.
- There was a negative relationship between vitamin D status and disease activity score in RA patients with active arthritis (P < 0.05).
- RA participants with vitamin D deficiency scored significantly worse in their health assessment questionnaire, quality of life indices, and beck depression inventory than those with sufficient vitamin D status (P < 0.05).
The researchers concluded,
“Vitamin D deficiency is highly prevalent in RA patients and is related with worse quality of life and a higher disease activity, the last only in patients with active arthritis.”
There were a couple of limitations to note about this study. A substantial portion of the RA participants in the study were only recently diagnosed with RA. These participants were likely to have higher disease activity, which may have led to a lower QoL. Another limitation is that vitamin D status was measured only once.
Prospective studies should be conducted in order to determine if there is a potential causal relationship between vitamin D status and QoL in RA patients.
Raczkiewicz, A. & Kulig, M. Vitamin D Status and Its Association with Quality of Life, Physical Activity, and Disease Activity in Rheumatoid Arthritis Patients. Journal of Clinical Rheumatology, (2015)