Background The FRAX index is a tool developed by the WHO that estimates the 10-year probability of hip fracture and a major osteoporotic fracture. It is calculated using an algorithm that includes clinical risk factors and can be calculated with or without densitometry data (femoral neck T-score). Its usefulness in patients with Early Arthritis (EA) is poorly studied
Objectives To evaluate if there is a difference between estimated 10-year fracture risk using the FRAX index, calculating it with and without densitometry data in patients with EA
Methods This is a prospective study of 101 patients from our EA Unit. At the baseline visit, a protocol was carried out which registered the following: sociodemographic data, anthropometric data, osteoporosis (OP) risk factors, bone metabolism laboratory parameters, rheumatoid factor and Anti-CCP, clinical disease activity (patient and physician scoring, pain, HAQ, number of tender and swollen joints, acute phase reactants), radiography of the dorsolumbar spine, hands and feet and bone densitometry (Hologic). The FRAX Index was calculated with and without densitometry data in patients over 40 years of age. Statistical analysis: descriptive and kappa index concordance test
Results At the initial visit, 39 patients were diagnosed with rheumatoid arthritis (ACR 1987 criteria) and the remainder were classified as undifferentiated arthritis. 84 women (83.2%) were studied, 40 premenopausal (pre-M) and 44 postmenopausal (post-M), as well as 17 (16.8%) men. The mean age was 52.7±16.6 years. The mean disease duration was 17.97±18.94 weeks with DAS28 mean 6.64±6.74. 12.9% had a family history of hip fracture, 10.9% had morphometric vertebral fractures, 75.2% started corticosteroid therapy after the initial visit, 41.3% were smokers or ex-smokers and 9.9% consumed alcohol. The prevalence of densitometric OP was 22.4% (7.8% pre-M, 34.9% post-M, 25% men) and the osteopenia 44.9% (43.6% pre-M, 46.5% post-M, 43.8% men). 22.1% of patients (20.45% post-M, 17.64% men, 1.25% pre-M) had a hip fracture risk greater than 3% according to the FRAX index calculated with densitometry and 27.8% without densitometry, which implies a concordance of 85% (p<0.000, kappa index 0.61). For a major risk of osteoporotic fracture greater than 20%, the concordance observed was 94% (p<0.00, kappa index 0.47): 5 (7.4%) patients without densitometry (6.82% post-M, 0% men and pre-M) and 3 (2.9%) with densitometry. An insignificant tendency that this concordance diminishes with age (53% in subjects over 70 years of age) was observed. The majority of patients in presented discordance had a hip T-score in the osteopenia range (between 1 and 2.5).
Conclusions In our patients with EA, the concordance observed when calculating the FRAX index with and without bone densitometry is very high, which makes it unlikely that performing densitometry would change the clinical risk of fracture and the indication for treatment. However, in a subgroup of our patients, introducing densitometry of the femoral neck only modified the clinical risk of fracture downwards
Disclosure of Interest None Declared