Vitamin D deficiency may be a risk factor for increased knee osteoarthritic pain in black Americans, according to a study published online November 7 in Arthritis & Rheumatism.
A study was conducted in which 94 adults completed questionnaires and underwent sensory testing for heat and mechanical pain. Participants were 75% women, they had an average age of 55.8 years, 45 were black, and 49 were white.
The researchers collected serum vitamin D levels at the beginning of sensory testing. They measured the heat pain threshold as when sensation "first becomes painful," and the pain tolerance as when the pain reaches the level of "no longer feel able to tolerate the pain." The researchers found that 38 of the 45 black participants (84%) had low vitamin D levels. On initial assessment, the researchers identified the most painful knee as the study index knee. Low levels of vitamin D were significantly associated with lower heat pain thresholds on the index knee as well as pressure pain on the index knee
In a news release, first author Glover said, "Our data demonstrate that differences in experimental pain sensitivity between the two races are mediated at least in part by variations in vitamin D levels. However, further studies are needed to fully understand the link between low vitamin D levels and racial disparities in pain. Although rare, vitamin D toxicity is possible and older adults should consult with their primary care provider regarding supplementation. It may be warranted that older black Americans with chronic widespread pain be screened for vitamin D deficiency to reduce disparities in pain."
According to the news release, the authors also plan to pursue research to test whether improving vitamin D status in older black and white patients affects their experience of chronic pain.
This study was supported by the National Institutes of Health/National Institute on Aging and the UF Clinical and Translational Science Institute. Glover is a John A. Hartford Foundation Building Academic Geriatric Nursing Capacity Scholar and a Mayday Fund grantee. The other authors have disclosed no relevant financial relationships.
Arthritis Rheum. Published online November 7, 2012. Abstract