Antiresorption therapy and reduction in fracture susceptibility in the osteoporotic elderly patient: open study.

The identification of risk factors for osteoporosis has been an essential step towards the understanding of the onset of the disease as well as of the osteoporosis-related fractures due to bone fragility. The present study has been aimed at assessing whether a correlation may exist between the increment in bone mass, consequent to an antiresorption therapy, and the reduction in the incidence of fractures. Moreover, the possibility that such a reduction might result from the action of other factors, such as the changes in bone microstructure, has been investigated. A total of 2,000 osteoporotic women (mean age: 68 +/- 9 years) were enrolled in the study and divided at random into 4 treatment groups. Each group received one of the following treatments: Alendronate 10 mg/daily (1,000 patients), Clodronate 100 mg/weekly i.m. (800 patients), Risedronate 5 mg/dailt (100 patients), and Raloxifene 60 mg/daily (100 patients). Clinical evaluation was based on bone mineral density (BMD) assay on lumbar vertebrae (L1-L4) by means of a DEXA (Lunar DPX) mineralometer, as well as on the incidence of fractures following both 12- and 24-month treatment periods. The results showed an overlapping pattern in patients treated with Alendronate or Risedronate, namely a significant increment in BMD after a 24-month treatment period, whereas such an increment in BMD was less evident in patients receiving either Clodronate or Risedronate after a 24-month treatment period. In addition, a total of 18 osteoporosis-related fractures were observed during the entire study period; 10 out of 18 fractures occurred in the Alendronate treated group, whereas the remaining 8 fractures were observed in the Clodronate treated group. Fourteen fractures were detected in patients over 80-year old, whereas the remaining 4 occurred in patients aged from 70 to 79 years and appeared to be independent of both the T-score assigned and the BMD increment obtained as a result of the therapy. Such findings suggest that the plain monitoring of BMD appears not to be adequate to anticipate clearly the danger of the probable onset of additional fractures, while the higher incidence of fractures in patients over 80-year old evidences that "old age" has to be considered the most serious risk factor for osteoporosis, since it is also the real responsible factor for changes taking place in bone microstructure.