Effect of Monthly Vitamin D on Chronic Pain Among Community-Dwelling Seniors: A Randomized, Double-Blind Controlled Trial

Abstract

OBJECTIVE With advancing age, the prevalence of vitamin D deficiency and musculoskeletal pain increases. However, published data on the effectiveness of vitamin D supplementation in reducing chronic pain are inconclusive. The purpose of this study was to test the effect of 3 different monthly doses of vitamin D on chronic pain in seniors 70 years and older with a prior fall event. DESIGN 1-year, double-blind randomized clinical trial. SETTING The trial was conducted in Zurich, Switzerland. Participants were 200 community-dwelling men and women 70 years and older with a prior fall. INTERVENTION Three study groups with monthly treatments were randomized to either a low-dose control group of vitamin D (24,000 IU vitamin D/mo), a high dose of vitamin D (60,000 IU vitamin D/mo), or a combination of calcifediol and vitamin D (24,000 IU vitamin D plus 300 μg calcifediol/mo). MEASUREMENTS The primary endpoint was the change in the mean number of painful areas using the McGill Pain map over 12 months of follow-up. All analyses were adjusted for age, sex, body mass index, 25-hydroxyvitamin (OH)D levels, and pain scores at baseline. A predefined subgroup analysis was performed by baseline 25(OH)D status (<20 vs ≥ 20 ng/mL). RESULTS The mean age of the participants was 78 years, 67.0% (134 of 200) were female, and 58.0% (116 of 200) were vitamin D deficient (<20 ng/mL) at baseline. Over 12 months of follow-up, the changes in the mean number of painful areas did not differ significantly among treatment groups (P = .46). However, there was a significant interaction effect between baseline vitamin levels (<20 vs ≥ 20 ng/mL) and treatment (P = .02). Among those who were vitamin D replete at baseline (n = 84), there was a significant difference between treatment groups over time (P = .04), and only seniors in the 24,000-IU vitamin D group had a marginally significant decrease in their total mean pain score (-0.77; 95% CI, -1.56 to 0.01, P = .05), whereas there were no changes in the high-dose groups. Among seniors who were vitamin D deficient at baseline (n = 116), chronic pain did not differ by treatment groups over time (P = .33). CONCLUSION Our results suggest that both starting level of 25(OH)D and monthly treatment dose of vitamin D may be important with respect to chronic pain reduction-with the only benefit seen among vitamin D-replete seniors treated with a monthly dose of 24,000 IU vitamin D