Association of Serum Vitamin D Levels With Inflammatory Response Following Hip Fracture: The Baltimore Hip Studies

• Published in: The journals of gerontology. Series A, Biological sciences and medical sciences Biological sciences and medical sciences, 2007-12, Vol.62 (12), p.1402-1406
• Main Authors: Miller, Ram R., Hicks, Gregory E., Shardell, Michelle D., Cappola, Anne R., Hawkes, William G., Yu-Yahiro, Janet A., Keegan, Achsah, Magaziner, Jay
• Format: Article
• Language: English
• Subjects: Aged; Aged, 80 and over; Body fat; Cohort Studies; Confidence intervals; Female; Gerontology; Hip Fractures - blood; Hip joint; Hospitals; Humans; Inflammation - etiology; Interleukin-6 - blood; Joint surgery; Nutrition; Older people; Patients; Rheumatoid arthritis; Sensitivity analysis; Studies; Vitamin D; Vitamin D - analogs & derivatives; Vitamin D - blood
• ISSN: 1079-5006; 1758-535X
• DOI: 10.1093/gerona/62.12.1402

Background. Vitamin D, known for its role in calcium homeostasis, may also regulate immune function. Whether vitamin D deficiency at the time of hip fracture is associated with the inflammatory response postfracture is not known. Methods. In a cohort from the Baltimore Hip Studies, women aged ≥65 years were evaluated at baseline and 2, 6, and 12 months after hip fracture repair. Serum at baseline was analyzed for 25-hydroxyvitamin D [25(OH)D], and serum from all time points was analyzed for interleukin-6 (IL-6). Participants were divided into two groups based on their baseline 25(OH)D levels. Vitamin D deficiency was defined as a 25(OH)D level of ≤15 ng/mL (< 37.5 nmol/L). We examined IL-6 level as a function of vitamin D status using generalized estimating equations, adjusting for covariates. Results. Women deficient in vitamin D at baseline had higher IL-6 levels in the year postfracture (p =.02). On average, participants with low 25(OH)D levels had adjusted serum IL-6 levels that were 6.0 pg/mL (95% confidence interval [CI]: −6.7, 18.7 pg/mL), 11.9 pg/mL (95% CI: 3.5, 20.4), 13.1 pg/mL (95% CI: 4.6, 21.6), and 13.4 pg/mL (95% CI: 2.3, 24.5) higher at baseline, 2, 6, and 12 months after hip fracture, respectively. Conclusions. Women with vitamin D deficiency at the time of hip fracture had higher serum IL-6 levels in the year after hip fracture. Whether the proinflammatory state of vitamin D deficiency explains the association of this deficiency with adverse outcomes in older adults warrants further study.