Study: Low Bone Density In African American Women With Lupus
Association between African American Race/Ethnicity and Low Bone Mineral Density in Women with Systemic Lupus Erythematosus
Arthritis & Rheumatism, Volume 57, Number 4, May 2007, pp. 582 – 592
What is Lupus?
Lupus is a chronic, inflammatory autoimmune disease that can result in complications affecting the skin, central nervous system, kidneys, heart and blood vessels, lungs, joints and bones. Lupus is more common in black women than any other group, occurs at a younger age and tends to be more severe in blacks.
What is the topic?
Women with lupus are at risk for osteoporosis and fractures. Furthermore, it is estimated that as many as 25% of pre-menopausal women with lupus may have osteopenia, or low bone mineral density (BMD), an early sign of osteoporosis.
What did the researchers hope to learn?
The researchers wanted to determine if African American women with lupus, like their Caucasian counterparts, were at risk for low bone density. They also wanted to examine the relationship between traditional osteoporosis risk factors and lupus-related risk factors as they related to BMD in women with lupus.
Who was studied?
A total of 298 women with lupus were recruited for this study, 77 African Americans and 221 non-Hispanic Caucasians.
How was the study conducted?
Each of the women had a single office visit that included an interview, a physical examination, and a measurement of bone density at both the hip and lumbar spine obtained through X-rays. Traditional osteoporosis risk factors that were looked at included age (at diagnosis of lupus and at time of the study visit); menopausal status; lifestyle factors; use of hormones; calcium and vitamin D intake; and use of medications (including osteoporosis medications). Lupus-related factors that were studied included the number of years with lupus, lupus disease damage scores, history of lupus-related renal disease, and the use of hydroxychloroquine and steroids. A series of statistical analyses were performed on these data to determine which risk factors were associated with low BMD.
What did the researchers find?
After adjusting for all the different variables, the researchers found that African American women were much more likely to have low BMD in the lower back (or lumbar spine) than Caucasian women; rates for low BMD values at the hip were about the same for African Americans and Caucasians. The researchers noted that bone of the lumbar spine is different from bone of the hip, and is more susceptible to damage from steroids, but their analysis indicated that steroid use alone could not account for the association between African American background and low BMD of the spine.
In addition to African American race, the researchers found several lupus-related factors associated with low BMD, including a greater history of overall organ damage and lupus kidney disease.
What were the limitations of the study?
BMD is a measurement based on the comparing the bone density that a person now has to a normal “peak” bone density, which occurs at age 30 in most of the population. The findings of low BMD in women with lupus may not necessarily indicate bone loss but could indicate that they ever did achieve the same level of peak bone mass as the population at large in their teens and twenties. There are limits to any study that compares outcomes between different ethnic/racial groups, since it is well known that these studies fail to account for the significant amount of interracial blending that has occurred over many generations.
What do the results mean for you?
Everyone with lupus is at increased risk for osteopenia and osteoporosis, even when their age, sex, or ethnic background might suggest otherwise if lupus were not present. There are, however, a number of medications (e.g., alendronate, trade names Fosamax®, Actonel®, Boniva®), dietary supplements (calcitonin, Vitamin D, calcium carbonate), and lifestyle adjustments (bone-strengthening exercises) that can help prevent or minimize bone loss, and it is important that these be considered in the overall management of lupus.