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Blacks had lower vitamin D and more quantifiable pain than whites with knee osteoarthritis – Nov 2012

Vitamin D, race, and experimental pain sensitivity in older adults with knee osteoarthritis

Arthritis & Rheumatism DOI: 10.1002/art.37687
T.L. Glover1,3,*, B.R. Goodin2, A.L. Horgas3, L.L. Kindler4, C.D. King1, K.T. Sibille1, C.A. Peloquin5, J.L. Riley III1, R. Staud6, L.A. Bradley7, R.B. Fillingim1,8
1 University of Florida, College of Dentistry, Community Dentistry & Behavioral Science
2 University of Florida, College of Dentistry, Comprehensive Center for Pain Research
3 University of Florida, College of Nursing
4 University of Portland, School of Nursing
5 University of Florida, College of Pharmacy and Emerging Pathogens Institute, Infectious Disease Pharmacokinetics Lab
6 University of Florida, College of Medicine
7 University of Alabama at Birmingham, School of Medicine, Division of Clinical Immunology and Rheumatology
8 North Florida/South Georgia Veterans Health System, Rehabilitation Outcomes Research Center
Email: T.L. Glover (tglover@ufl.edu)
*University of Florida, College of Dentistry, 1395 Center Drive, Dental Tower, Room D2-13, P.O. Box 100404, Gainesville, FL 32610
Copyright © 2012 by the American College of Rheumatology

Low levels of serum circulating 25-hydroxyvitamin D have been correlated with many health conditions, including chronic pain. Recent clinical practice guidelines define vitamin D levels < 20 ng/mL as deficient and values of 21-29 ng/mL as insufficient. Vitamin D insufficiency, including the most severe levels of deficiency, is more prevalent in black Americans. Ethnic and race group differences have been reported in both clinical and experimental pain, with black Americans reporting increased pain. The purpose of this study was to examine whether variation in vitamin D levels contribute to race differences in knee osteoarthritic pain.

The sample consisted of 94 participants (75% female), including 45 blacks and 49 whites with symptomatic knee osteoarthritis. Average age was 55.8 years (range 45-71 years). Participants completed a questionnaire on knee osteoarthritic symptoms and underwent quantitative sensory testing, including measures of heat and mechanical pain sensitivity.

Blacks had significantly lower levels of vitamin D compared to whites, demonstrated greater clinical pain, and showed greater sensitivity to mechanical and heat pain.
Low levels of vitamin D predicted increased experimental pain sensitivity, but did not predict self-reported clinical pain.
Group differences in vitamin D significantly predicted group differences in heat pain and pressure pain thresholds on the index knee and ipsilateral forearm.

These data demonstrate race differences in experimental pain are mediated by differences in vitamin D level.
Vitamin D deficiency may be a risk factor for increased knee osteoarthritic pain in black Americans.
© 2012 American College of Rheumatology.

See also VitaminDWiki