Maureen Salamon

October 26, 2016

NEW ORLEANS — For patients with spinal cord injury who have insufficient levels of vitamin D, supplements can improve symptoms of depression and fatigue, report investigators.

And in these patients, pain severity scores were significantly better with high-dose supplements than with low-dose supplements. Supplementation did not, however, enhance muscle strength.

"We need to screen everyone with spinal cord injury for vitamin D," said investigator Gavin Williams, MD, PhD, a physical medicine and rehabilitation resident in the Department of Orthopaedic Surgery at Stanford University in Palo Alto, California.

"We probably should be more aggressive with supplementation than current NIH guidelines suggest," he told Medscape Medical News. The daily vitamin D recommendation for adults is 600 to 800 IU, but "we see a quicker and more robust response with a much higher dose," he reported.

Dr Williams and his colleagues examined the effect of vitamin D supplementation on pain, fatigue, depression, and muscle power in 20 patients with acute spinal cord injury and 22 with chronic spinal cord injury. At baseline, all levels of 25-hydroxyvitamin D were below 30 ng/mL.

Patients randomly allocated to the low-dose group received 800 IU of vitamin D daily for 6 months. Those randomly assigned to the high-dose group received 2000 IU daily for 6 months if their baseline blood levels were 20 to 30 ng/mL; they received 4000 IU daily for 1 month and 2000 IU daily for 5 months if their baseline blood levels were lower than 20 ng/mL.

Outcome measures tracked at baseline, 1 month, 3 months, and 6 months included the Beck Depression Inventory (BDI), the Modified Fatigue Impact Scale, the Brief Pain Inventory (BPI), and dynamometry scores.

During the study period, all patients experienced a significant increase in average 25-hydroxyvitamin D levels (P < .01). High-dose supplementation was associated with a significant decrease in BDI scores (P = .034). In addition, high-dose supplementation was linked to a significantly greater improvement in BPI scores than low-dose supplementation (P = .034).

However, although scores had improved in high-dose patients at 3 months, that benefit was not significant at 6 months, Dr Williams reported. The variation in dynamometry scores was minimal, regardless of dose.

 
We're looking for one more factor we can optimize. Dr Gavin Williams
 

Previous research has established that patients with spinal cord injury are four to five times more likely to be at risk for insufficient 25-hydroxyvitamin D levels than able-bodied people in the general population. Therefore, these patients should be the focus of supplementation research in the future, Dr Williams said.

Even the study participants who lived in "sunny California" had low levels of vitamin D at baseline, he pointed out. "Vitamin D doesn't just contribute to bone health, but cardiopulmonary health as well, which is very important in spinal cord patients because they're not able to exercise as well as able-bodied people," he added. "We're looking for one more factor we can optimize."

This study was small, and some patients with acute spinal cord injury were lost to follow-up, Dr Williams acknowledged. However, no participants experienced severe adverse events. The most common adverse effect that was related to vitamin D supplementation was constipation.

These data might compel physicians to consider routinely measuring vitamin D levels in spinal cord injury patients and encouraging supplementation in those with low levels, said Jeffrey Cohen, MD, a clinical professor of rehabilitation at the Rusk Institute of Rehabilitation Medicine at the NYU Langone Medical Center in New York City.

This study shows that "vitamin D supplementation appears to be safe and can potentially lead to improvements in the fatigue and depression that are so predominant in this population," Dr Cohen told Medscape Medical News.

However, other studies have shown that vitamin D supplementation might also have an effect on muscle strength. For instance, a study of elite wheelchair athletes with spinal cord injuries and low vitamin D serum levels showed improved muscle strength after 12 weeks of vitamin D supplementation (Nutrients. 2016;8:E374), he explained.

"There's a lot to be learned here," said Dr Cohen.

 
This is important research, but we need to be very, very tight with outcome measures. Dr David Gater
 

"This is important research, but we need to be very, very tight with outcome measures," said David Gater, MD, PhD, professor and chair of physical medicine and rehabilitation at the Penn State Milton S. Hershey Medical Center in Hershey, Pennsylvania, who attended the presentation.

Vitamin D supplementation "is a huge area of controversy in our field, as well as many others," he pointed out. And the cause-and-effect relation between vitamin D and better fatigue and depression scores has not been established, he pointed out.

The study was funded by the American Spinal Injury Association and the Sam Schmidt Paralysis Foundation. Dr Williams, Dr Cohen, and Dr Gater have disclosed no relevant financial relationships.

American Academy of Physical Medicine and Rehabilitation (AAPMR) 2016 Annual Assembly. Abstract S153. Presented October 21, 2016.

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