This study aimed to determine whether vitamin D is associated with mortality in patients with osteoarthritis.

A musculoskeletal disorder, osteoarthritis (OA), affected approximately 527.8 million people worldwide in 2019. More than 32.5 million people in the United States have OA, making it the most prevalent cause of pain and disability.

Additionally, OA significantly impacts physical and mental health, and such a prevalent disease has affected societal and personal costs. The pathogenesis and progression of OA include joint structures, non-modifiable aspects(age, gender, etc.), and adjustable elements such as obesity and Vitamin D status.

Vitamin D, a steroidal hormone, is responsible for various biological effects on target tissues. For example, its roles in the calcium metabolism of bones make it a powerful preventative and therapeutic tool for osteoarthritis.

Vitamin D supplementation improved joint function and alleviated pain in knee OA patients with low serum Vitamin D levels. However, a conclusive result has yet to be reached.

In addition to improving outdoor activity and mental health, Vitamin D may contribute to better quality and quantity of survival in patients with OA. Also, vitamin D has been shown to reduce inflammation, proliferation, and oxidative stress in many non-skeletal diseases, including cardiovascular disease (CVD), diabetes, and cancer.

This study included participants with self-reported osteoarthritis from NHANES III and NHANES 2001–2018. Restricted cubic splines and Cox regression were used to evaluate the association between 25(OH)D concentrations and mortality risk to determine the robustness of the results.

Results of the Study

In total, 4570 patients were included, of whom 1388 died by 31 December 2019. In addition, 25(OH)D concentrations were positively associated with all-cause mortality, while cardiovascular disease (CVD) mortality was negatively associated.

All-cause mortality had an adjusted hazard ratio of 1.00 (reference), 0.49, 0.45, and 0.43; CVD-specific mortality had an adjusted hazard ratio of 1.00 (reference), 0.28, 0.25, and 0.24; cancer-specific mortality did not have a significant association. Analyses based on stratification and sensitivity showed similar results.

The results demonstrate that Vitamin D significantly reduces mortality rates from all causes and CVD compared with patients with low or deficient serum 25(OH)D levels.

As a result of this study, vitamin D was found to be beneficial to long-term outcomes, namely mortality reduction. Additionally, experts found that, when similar covariates were adjusted, the researchers’ HRs were slightly smaller than those reported among diabetic patients based on rough comparisons.

Thus, the significance of adequate Vitamin D intake in OA patients is highlighted by the finding that OA patients may benefit more from higher Vitamin D levels than diabetic patients.

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