Low vitamin D levels predict mortality in ankylosing spondylitis patients

Vitamin D deficiency is a global epidemic and has been linked to many autoimmune diseases, including type 1 diabetes, systemic lupus erythematosus, multiple sclerosis, and (inflammatory bowel disease) IBD, with studies finding a higher prevalence of these diseases in those who are deficient in vitamin D.

Previous studies in patients with ankylosing spondylitis have reported lower vitamin D levels compared to controls, however, the effect of vitamin D status on disease severity has been controversial. Some studies demonstrated that a vitamin D deficiency increased the disease severity while others did not show an association. Most of these studies were cross-sectional studies, had a small sample size, and none examined vitamin D levels on mortality in ankylosing spondylitis patients.

According to a study published two weeks ago in Nutrients, researchers investigated the effect of vitamin D deficiency on all-cause mortality in patients with ankylosing spondylitis and in the general population.

This was a retrospective cohort study including 919 patients with ankylosing spondylitis (AS) diagnosed between 2002 and 2007 and 4,519 controls. The average age at the start of the study was 52 years with 22% of them being women. The follow up continued until death or at the end of study in July 2019 with an average follow-up time of 14.3 years. Laboratory assessment included 25-hydroxyvitamin-D levels.

As seen with other autoimmune conditions, AS was associated with a higher proportion of vitamin D deficiency (< 20 ng/mL) and a vitamin D insufficiency (< 30 ng/mL) was significantly associated with increased incidence of all-cause mortality. This association was more prominent with a vitamin D deficiency and among male patients. On the other hand, inadequate levels of vitamin D among healthy controls were not associated with an increased all-cause mortality.

This study demonstrated that a vitamin D deficiency is more common in AS patients than healthy controls and is associated with an increased risk for all-cause mortality. This is most likely due to the role of vitamin D as an immunomodulator. Vitamin D inhibits the production of several cytokines including tumor necrosis factor alpha (TNF-α) which plays a role in joint inflammation and rheumatic diseases.

Most patients can obtain optimal levels of vitamin D in daily doses between 5,000 IU and 10,000 IUs/day. Research suggests daily dosing is more effective than weekly dosing. It is also essential to use a supplement that combines vitamin K or provide a separate vitamin K supplement. There are intricate relationships between fat-soluble vitamins and it is important take this into account with dosing vitamin D supraphysiologically.

By Michael Jurgelewicz, DC, DACBN, DCBCN, CNS

Source: Ben-Shabat N, Watad A, et al. Low Vitamin D Levels Predict Mortality in Ankylosing Spondylitis Patients: A Nationwide Population-Based Cohort Study. Nutrients. 2020 May 13;12(5), 1400.