Low levels of vitamin D are associated with higher rates of end-stage renal disease in patients who have systemic lupus erythematosus (SLE), according to new research findings presented at the 2017 ACR/ARHP Annual Meeting in San Diego.
To clarify the role that vitamin D levels may play in lupus inflammation, researchers at Johns Hopkins University School of Medicine in Baltimore conducted a study to determine how low vitamin D levels could predict later organ damage.
Although lupus can develop in anyone, the condition occurs 9 or 10 times more often in women than in men and is 2 or 3 times more common among women of color, the researchers noted. Vitamin D insufficiency or deficiency is a common problem for patients with SLE, and some evidence suggests that vitamin D replacement therapy may help improve renal disease activity, they added.
The investigators analyzed data on 1392 patients with SLE, including their first medical office visit during which vitamin D levels were measured, and then their organ or tissue damage on all of the patients’ follow-up clinic visits.
The patients were 92% female, had a mean age of 47.3 years, and were 50% Caucasian and 41% African-American. They were categorized based on 25-hydroxy vitamin D levels that were below 20 ng/mL or at or above 20 ng/mL on their first office visit. At their first office visit in which vitamin D levels were measured, 27.3% had levels below 20 ng/mL.
The researchers then calculated the risk of lifetime organ damage for patients who had low vitamin D levels using the Systemic Lupus International Collaborating Clinics/American College of Rheumatology (SLICC/ACR) Damage Index scoring system. Organ damage rates were adjusted for age, gender, and ethnicity.
“We have shown that supplementing vitamin D reduces urine protein, which is the best predictor of future renal failure,” said Michelle A. Petri, MD, PhD, Director, Hopkins Lupus Center and a lead author.
The relative risk (RR) of renal damage was the highest for patients with SLE whose vitamin D levels were insufficient (RR, 1.87; 1.66 adjusted). Skin damage was another concern, with an RR of 1.69 (1.22 adjusted). Total organ damage RR was 1.11 (1.17 adjusted).
Other measured long-term outcomes included ocular, neuropsychiatric, pulmonary, cardiovascular, GI, and musculoskeletal, but the RR of damage to these organ systems was not significant. There was no association between low vitamin D and musculoskeletal damage, including osteoporotic fractures.
The researchers concluded that low vitamin D is associated with a higher risk of total organ damage and with end-stage renal disease for patients with lupus.
“Supplementary vitamin D is very safe,” said Dr Petri. “It helps to prevent one of the most dreaded complications of SLE, and likely has a role in preventing blood clots and cardiovascular disease as well. Vitamin D supplementation, which can reduce proteinuria, should be a part of the treatment plan for lupus nephritis patients.”
This research was supported by funding from the NIH’s National Institute of Arthritis and Musculoskeletal and Skin Diseases.