ABSTRACT. METHODS. SUBJECTS Baseline data of 271 female from three institutions in Canada (Montreal, Toronto, London) who were currently enrolled in the Health Improvement and Prevention Program (HIPP) study
Bone Mineral Densities:
Objectives: In women with systemic lupus erythematosus, to determine: 1) osteoporosis (OP) and low bone mass (LBM) prevalence in women age>50 and <50, 2) fracture risk using the Canadian Fracture Risk Assessment Tool (FRAX) in women>40, 3) bone quality by Hip Structural Analysis (HSA), and 4) correlations between FRAX and HSA with SLE/OP risk factors.
Methods: Demographics including age, SLE duration, and OP risk factors were collected from 271 participants without OP. Bone mineral densities (BMD) at the hip, spine, and femoral neck (f-neck) were determined by DXA. WHO definitions of OP were used for females>50 (32.8%) while LBM was defined as z-scores<-2 for those<50. For those>40 (63.5%), 10-year probabilities of a major fracture (FRAX-Major) and hip fracture (FRAX-Hip) were calculated. High fracture risk is FRAX-Major>20% or FRAX-Hip>3%. Low risk is FRAX-Major<10% or FRAX-Hip<1%. HSA was completed in 81 participants to derive section modulus (SM, bending strength) and buckling ratio (BR, cortical stability) at the f-neck. BR>10% is considered high risk.
Results: Subjects had a mean (SD) age of 43.8 (13.0), SLE duration of 11.6 (10.4) years, 38% were postmenopausal, 13% had prior non-OP fractures, and 41% used corticosteroids for>3 months.
OP and LBM were diagnosed in 14.6% and 8.8% respectively. Significant negative correlations existed between f-neck (r=-0.31, p=0.001) and hip BMD (r=-0.41, p<0.01) with corticosteroid duration.
The mean FRAX-Major was 10.2% (6.3) and FRAX-Hip was 1.9% (3.3). FRAX-Major>20% was seen in 12 patients (7 treated). FRAX-Hip>3% was seen in 27 (18 treated). Treatment was given to 19.4% and 14.6% with FRAX-Major<10% and FRAX-Hip<1% respectively. FRAX-Major correlated significantly with: corticosteroid duration (r=0.33, p=0.008) and age (r=0.21, p=0.01). FRAX-Hip correlated significantly with: corticosteroid duration (r=0.35, p=0.03), age (r=0.23, p=0.02), and SLE duration (r=0.20, p=0.01).
The mean BR was 9.5 (2.2). BR>10% was in 43.2%. BR significantly correlated with: FRAX-Major (r=0.538, p<0.01), FRAX-Hip (r=0.599, p<0.01), age (r=0.232, p=0.037), SLE duration (r=0.435, p<0.01), and corticosteroid duration (r=0.285, p=0.026). SM and SLE/OP factors had no associations.
Conclusion: OP and LBM are prevalent in SLE women. FRAX and HSA provide insight to fracture risk by deriving probabilities for prescribing treatment or assessing bone structure non-invasively.
SLE FEMALES IN HIPP STUDY (n= 271)
FEMALES > 50 (n=89)
FEMALES < 50 (n=182)
LOW BONE MASSz-score < -2.0 (n=16)
t-score < -2.5 (n=13)
Figure 1.0: Prevalence calculation stratified according to age
Figure 2.0: FRAX Questionnaire
In women with SLE, to determine the:
Fracture Risk Assessment and Hip Structural Analysis in Canadian Females Living with Systemic Lupus Erythematosus (SLE)
JJ. Lee, AM. Cheung, E. Aghdassi, S. Morrison, V. Peeva, C. Neville, S. Hewitt, D. Da Costa, J. Pope, PR. Fortin. Division of Rheumatology, The University Health Network, Toronto, Canada, McGill University, Montreal, UWO, London ON.
TABLE 4: FRAX SCORES IN SLE FEMALES >40
TABLE 1: DEMOGRAPHIC CHARACTERISTICS
TABLE 5: HSA IN A SUBSET OF FEMALES (n=81)
ASSOCIATIONS OF BMD VALUES WITH SLE/OP RISK FACTORS
ASSOCIATIONS OF FRAX SCORES WITH SLE/OP RISK FACTORS
ASSOCIATIONS OF HSA WITH SLE/OP/FRAX RISK FACTORS
Fracture Risk Assessment Tool (FRAX):
FRAX-Major: Probability of major osteoporotic event in 10 years
FRAX-Hip: Probability of hip fracture event in 10 years
FRAX-Major >20% are at high risk and need OP treatment
FRAX-Hip >3% are at high risk and need OP treatment
TABLE 2: BONE MINERAL DENSITY AND PREVALENCE OF OSTEOPOROSIS IN FEMALES >50
Hip Structural Analysis (HSA):
Section Modulus (SM): Index of bending loads
Buckling Ratio (BR): Estimate of cortical stability and susceptibility to buckling under loads
SM decreases fracture risk, BR increases fracture risk
BR >10% is considered high fracture risk
TABLE 3: BONE MINERAL DENSITY AND PREVALENCE OF LOW BONE MASS IN FEMALES <50
Figure 3.0 HSA assessment of structural dimensions
The study was funded by the Canadian Institute for Health Research and The Arthritis Society