Low-income people with systemic lupus erythematosus (SLE) are at higher risk of getting bone fractures than their non-SLE counterparts. The risk is even greater when lupus nephritis is present, a study suggests.
The study, “Comparative Fracture Risks among US Medicaid Enrollees with and without Systemic Lupus Erythematosus,” was published in Arthritis & Rheumatology.
SLE patients tend to have reduced bone health compared with the general population, probably due to chronic inflammation and long-term treatment with glucocorticoids. This is especially true for low-income patients, who have a higher incidence of SLE-related complications.
Lupus nephritis is an additional risk factor for diminished bone health, since people with this condition often present hyperparathyroidism — excessive production of hormones by the parathyroid glands — and vitamin D deficiency, both of which alter bone formation.
SLE patients, especially those with low incomes and with lupus nephritis, might be at higher risk for bone fractures but this has not been evaluated in studies with a large sample size.
Therefore, researchers studied users of Medicaid — the U.S. public health insurance program that covers low-income, racially and ethnically diverse individuals — between 2007 and 2010 to see if people with SLE presented more fractures than those without the condition, and if lupus nephritis was an additional risk factor.
The study included 47,709 SLE patients, 9,449 of whom had lupus nephritis, and compared their data to those of 190,836 users without SLE that were matched for age and sex. The mean age was 41.4 years (ranging from 18 to 65), and 92.6% of participants were female.
SLE patients presented 4.32 fractures per 1,000 persons per year; the value for those with lupus nephritis was 4.6, and for the non-SLE group, it was 2.4. The SLE group, with or without lupus nephritis, reported mostly pelvic fractures whereas the non-SLE group mostly presented wrist fractures.
People with SLE had twice the risk of fracture than their non-SLE counterparts. Those with lupus nephritis had a three times greater risk than the non-SLE group, and a 1.6 times greater risk than lupus patients without nephritis.
Researchers noted that “because we conducted this analysis among Medicaid enrollees, our results may not generalize to other SLE patients with higher socioeconomic status.”
More than 40% of SLE patients in the study used glucocorticoids, so “it is possible that SLE patients in our cohort had worse bone health due to SLE itself or as a consequence of glucocorticoid use,” the study stated. However, glucocorticoids accounted for some but not all of the increased risk.
The researchers concluded that people with SLE have more fractures and more of them with complications. “This work underscores the importance of identifying high-risk SLE and lupus nephritis patients for fracture prevention,” they added.