Associations between vitamin D status and pain in older adults: The Invecchiare in Chianti Study

OBJECTIVES: To examine cross-sectional associations between vitamin D status and musculoskeletal pain and whether they differ by sex. DESIGN: Population-based study of persons living in the Chianti geographic area (Tuscany, Italy). SETTING: Community. PARTICIPANTS: Nine hundred fifty-eight persons (aged >= 65) selected from city registries of Greve and Bagno a Ripoli. MEASUREMENTS: Pain was categorized as mild or no pain in the lower extremities and back; moderate to severe back pain, no lower extremity pain; moderate to severe lower extremity pain, no back pain; and moderate to severe lower extremity and back pain (dual region). Vitamin D was measured according to radioimmunoassay, and deficiency was defined as 25-hydroxyvitamin D (25(OH)D) less than 25 nmol/L. RESULTS: The mean age +/- standard deviation was 75.1 +/- 7.3 for women and 73.9 +/- 6.8 for men. Fifty-eight percent of women had at least moderate pain in some location, compared with 27% of men. After adjusting for potential confounders, vitamin D deficiency was not associated with lower extremity pain or dual-region pain, although it was associated with a significantly higher prevalence of at least moderate back pain without lower extremity pain in women (odds ratio=1.96, 95% confidence interval=1.01-3.59) but not in men. CONCLUSION: Lower concentrations of 25(OH)D are associated with significant back pain in older women but not men. Because vitamin D deficiency and chronic pain are fairly prevalent in older adults, these findings suggest it may be worthwhile to query older adults about their pain and screen older women with significant back pain for vitamin D deficiency.