A recent meta-analysis found a relationship between vitamin D deficiency and chronic widespread pain.
Chronic widespread pain (CWP) is a global musculoskeletal disorder, affecting between 10%-18% of the general population. Symptoms of CWP include pain lasting for at least 3 months, as well as circulatory, respiratory and neurological system problems. Individuals who suffer from CWP may experience a tremendous physical and psychosocial burden.
Researchers believe that vitamin D may be a factor in the development of CWP. In fact, osteomalacia, or adult rickets, is considered to be the most severe type of CWP resulting from vitamin D deficiency. As discussed recently, those with osteomalacia may experience general body aches, especially along the shoulder, rib cage, lumbar and pelvic regions. However, aside from osteomalacia, the mechanism behind vitamin D in the development or treatment of CWP has yet to be confirmed.
Several studies have aimed to determine the biological role of vitamin D in CWP; though, results have been inconclusive. This may be due to the variability (heterogeneity) of studies, different thresholds used to define vitamin D deficiency and various confounding factors. Therefore, researchers conducted a meta-analysis to evaluate whether vitamin D deficiency is associated with CWP and to determine if this relationship is independent of common cofounders, including but not limited to sun exposure, socioeconomic status, and gender.
The researchers included all case control studies that assessed the prevalence of vitamin D deficiency or serum vitamin D levels in both CWP patients and healthy controls through 2014. Of the 12 studies which met the inclusion criteria, 9 included the odds ratios of vitamin D deficiency and CWP. A subgroup analysis was also performed according to gender, vitamin D deficiency threshold and criteria for diagnosing CWP.
The researchers found that CWP patients were 63% more likely to be vitamin D deficient than controls; though, when accounting for confounding variables this decreased to a 41% increased risk. Studies that used a lower diagnostic value to define hypovitaminosis D (8-10 ng/mL) found those with CWP were more likely to be deficient.
The researchers concluded:
“Our meta-analysis, employing data from 12 studies involving 1,854 patients and 7,850 controls, found that participants with CWP were associated with serum hypovitaminosis D and the association was likely to exist after adjusting potential confounding factors.”
This meta-analysis provides further support to the theory that vitamin D status is inversely associated with CWP. Although successfully confirming its hypothesis, there are some limitations to note. Due to the observational design of the studies, the results proved association only, not causality. Also, not all of the studies included odds ratios, and the diagnostic value of vitamin D deficiency varied from studies, thereby decreasing the strength of the findings.
Future randomized controlled trials are needed to determine if a causal relationship exists between vitamin D and CWP.
Sturges, M. & Cannell, JJ. Meta-analysis shows vitamin D status is inversely associated with chronic widespread pain. The Vitamin D Council Blog/Newsletter, December 2015.