Background Denosumab is the first biological treatment for osteoporosis in postmenopausal women at high risk of fracture or who have failed, or are intolerant to other osteoporosis treatment.

Objectives To compare the effect of the treatment with denosumab to alendronate in postmenopausal women with osteoporosis and at high risk of fractures with regard to the variation of bone mineral density (BMD) and the incidence of new fractures.

Methods This is a longitudinal and prospective study conducted at an outpatient rheumatology division of La Paz University Hospital, Madrid, Spain. Between 126 postmenopausal women ≥65 of age, with severe osteoporosis and history of fractures in most of them, who received 70mg alendronato (ALN) every week for more than two years, 75 patients suspended ALN for different reasons and they signed an informed consent to continue treatment with 60mg denosumab subcutaneously every 6 months. The other patients (n=51) decided to continue with 70 mg ALN every week. All patients received supplements of calcium and vitamin D, according to the individual levels. End points included percentage change from the beginning of the study in lumbar spine (LS) and femoral neck (FN) BMD at month 12 and new fractures incidence by dorsolumbar x-ray and clinic history.

Results Denosumab-treated women and ALN-treated women were similar age: 73.8±7.1 and 71.7±6.0 years old, respectively. At month 12, significantly greater BMD increase from baseline were observed with denosumab compared with alendronate at LS (6.2±5.7% compared with 3.5±1.6%; p<0.001) and FN (4.3±4.9% compared with 1.9±1.5%; p=0.028). Reasons for ALN suspension were: 41.3% by lack of effectiveness in BMD increasing, 28% by intolerance gastroesophageal, 18.7% for new vertebral fractures, and 12% by decision of the patient. At basal time 62.7% of denosumab-treated women had suffered one or more osteoporotic fractures, after one year were not detected new fractures, all them received 2 doses of denosumab. At baseline, 58.8% ALN-treated women had fractures and after one year one vertebral and two Colles fractures were occurred and 87% of them completed treatment. Poor tolerance to subcutaneous injection or adverse events in any of the two treatment groups were not observed. Denosumab treated women expressed pleasure facility involving the semiannual administration of treatment.

Conclusions In postmenopausal women with severe osteoporosis previously treated with alendronate, denosumab treatment resulted in greater BMD increases in lumbar spine and femoral neck than alendronate, probably associated with the better adherence due to the highest degree of satisfaction of the patients manifest to receive a six-monthly injection treatment.

Disclosure of Interest None declared

DOI 10.1136/annrheumdis-2014-eular.2881