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We were interested in the finding by Atherton and colleagues of an association between current vitamin D status and chronic widespread pain (CWP). The authors conclude: “Follow-up studies are needed to evaluate
whether higher vitamin D intake might have beneficial effects on CWP risk”.
We are completing a large randomised, placebo-controlled trial on vitamin D and can contribute preliminary re...
We are completing a large randomised, placebo-controlled trial on vitamin D and can contribute preliminary results to this debate. The ‘Vital D’ study has over 2,000 women aged 70+ years. The randomised
participants received an annual dose of either 500,000IU cholecalciferol or placebo and have received study medication for 3 to 5 years. A randomised subset of 100 participants had pathology taken at the time of
completing the SF-12 questionnaire, coinciding with autumn/winter and one-year after the final dose of study medication. Serum vitamin D (Diasorin) and parathyroid hormone (PTH) levels were measured using the RIA and ELISA
We analysed our data for an association between vitamin D status and the two pain-related questions from SF-12. Question 8 “During the past 4 weeks, how much did pain interfere with your normal work?” – answers are
categorical ranging from “not at all” to “extremely”; Question 12 “During the past 4 weeks, how much of the time has your physical health or emotional problems interfered with your social activities (like visiting friends and relatives etc)?” – participants selected a category ranging from “all of the time” to “none of the time”. Results were analysed by logistic regressions using log transformed data and age-adjusted where appropriate (Minitab™-15). Pathology samples from 97 participants are
available (54=active; n=43 placebo).
Serum vitamin D and PTH were both predictive of the amount of time that physical health or emotional problems interfered with social activities (p<0.001). Women with lower vitamin D and higher PTH were more likely to have ill health impact on their social activities. The
relationship was stronger for PTH than vitamin D (p=0.001 and p=0.041, respectively); the median PTH for women indicating higher impact of ill health on social activities was 7.1 pmol/L (IQR: 4.5 to 11.7) compared
with 4.4 pmol/L (IQR: 3.4 to 6.1) for those experiencing little interference through health problems. The corresponding vitamin D medians were 48 nmol/L (IQR: 42 to 80) compared with 53 nmol/L (IQR: 40 to 70).
Although we did not find a direct association between serum vitamin D or PTH with interference from pain (p=0.279 and p=0.132, respectively), response to the pain question was moderately and significantly correlated
to the amount of time that health problems interfered with social activities (Pearson correlation=0.4; p<0.000). Participants with more interference from pain were 2.3 (95% CI: 1.4, 3.8) times more likely to experience higher interference of social activities due to health problems.
The analysis suggests lower vitamin D and higher PTH levels are associated with reduced health-related quality of life. This association was stronger with PTH than vitamin D. Although our results did not demonstrate a direct association between vitamin D status and our index of pain, those with higher vitamin D and lower PTH levels (better vitamin D status) had less interference on social activity through physical ill health or emotional problems. Our results did not demonstrate a direct
link of vitamin D status with pain but rather an inferred effect through the relationship between pain and health status.
1. Atherton K, Berry D, Macfarlane G, Power C, Hypponen E. Vitamin D and chronic widespread pain in a white middle-aged British population: evidence from a cross-sectional population survey. Ann Rheum Dis 2008;Aug
12 [Epub ahead of print].