Cumulative steroid dosage is a risk factor for the development of osteonecrosis (ON), which is the most frequent type of damage in lupus patients, according to research presented at the European League Against Rheumatism (EULAR) Congress 2017, held June 14 to 17 in Madrid, Spain.
Researchers from Hanyang University Hospital for Rheumatic Diseases in Seoul, Republic of Korea, researched the factors associated with ON in a single Asian cohort, with a specific focus on musculoskeletal damage.
After recruiting 1219 patients with systemic lupus erythematosus (SLE), the researchers confirmed ON by X-ray, bone scan, or magnetic resonance imaging. Musculoskeletal was the most common type of organ damage observed (205 patients, 16.8%). ON was the most commonly observed subtype of musculoskeletal damage (133 patients, 10.9%). The researchers also found that the mean time of SLE diagnosis to development of ON was 4.97±4.15 (range, 0.17~20.25) years.
Overall, 291 joints in 126 eligible patients were affected by ON, and the average number of ON joints per patient with ON was 2.3±1.23 (range, 1~9). The percentage of >2 joint involvement was 24.6%. The most frequently involved joint was the hip (femoral head, 65.6%), followed by the knee (distal femur, proximal tibia, proximal fibula, patella: 20.6%), shoulder (humeral head: 5.2%), and ankle (distal tibia, distal fibula, talus: 5.2%).
“In univariate analysis, age at diagnosis, follow up duration, accumulative number of [American College of Rheumatology] criteria, serositis, renal disorder & neurologic disorder (based on [American College of Rheumatology] criteria), cyclophosphamide & mycophenolate use, and cumulative steroid dosage were significantly associated with ON,” the researchers wrote. “In multivariate analysis, renal disorder (P =.0109), and cumulative steroid usage (P =.0131) were significantly associated with ON.”
The researchers also evaluated the effect of cumulative steroid usage on ON by dividing cumulative steroid dosage. Dosage was divided into 4 groups by grams: >0 and ≤5 g, >5 and ≤10g, >10 and ≤20 g, and >20g. More than 10 g of cumulative steroid use was significantly associated with ON.
The researchers then stratified 530 patients according to biopsy-proven lupus nephritis (class III-V) and cumulative steroid dose (10-g cut-off), tested by Chi-square test and logistic regression. ON was significantly higher in the group with lupus nephritis within the >10 g group of total cumulative steroid.
“ON was the most frequent damage in lupus patients,” the researchers concluded. “We confirmed again cumulative steroid dosage as a risk factor for the development of ON. In addition, lupus nephritis itself was suggested as an independent risk factor for ON.”
Kwon HH, Won S, Joo YB, et al. Osteonecrosis is the most common damage and is associated with cumulative steroid dosage as well as lupus nephritis itself in patients with SLE. Presented at: European League Against Rheumatism (EULAR) Congress 2017; June 14-17, 2017; Madrid, Spain. doi:10.1136/annrheumdis-2017-eular.4547