Superiority of a combined treatment of Alendronate and Alfacalcidol compared to the combination of Alendronate and plain vitamin D or Alfacalcidol alone in established postmenopausal or male osteoporosis (AAC-Trial)

A combined therapy with the strongly antiresorptive Alendronate and the pleiotropically acting D-hormone analogue Alfacalcidol may have additive effects on bone quality, falls and fracture risk in established osteoporosis. The aim of this study (Alfacalcidol Alendronate Combined—AAC) was to compare the efficacy and safety of a combined parallel therapy with Alendronate and Alfacalcidol to the treatment with either Alendronate in combination with plain vitamin D or Alfacalcidol alone in patients with established postmenopausal or male osteoporosis. Ninety patients were included as matched triplets to receive randomly either 1 μg Alfacalcidol daily + 500 mg calcium (group A, n = 30) or 70 mg Alendronate weekly + 1,000 mg calcium + 1,000 IU vitamin D daily (group B, n = 30) or 1 μg Alfacalcidol daily + 70 mg Alendronate weekly + 500 mg calcium daily (group C, n = 30). Patients were recruited in one centre and were followed up for 24 months. Analysis was intention-to-treat and the primary outcome was lumbar spine and total hip bone mineral density (measured observer blind). BMD was measured at the lumbar spine and at the proximal femur with dual energy X-ray absorptiometry (LUNAR Prodigy, GE, USA) at the beginning and after 12 and 24 months. During the 2-year-study we observed descriptively significant increases at the lumbar spine of 3.0% in group A compared to baseline, of 5.4% in group B and of 9.6% in group C, respectively. The superiority of the Alendronate + Alfacalcidol treatment group over Alfacalcidol alone and over Alendronate + vitamin D was of more than large relevance (both tests: MW > 0.71; CI-LB > 0.64; P < 0.001). We also observed median increases of the BMD at the total hip of 1.5% in group A, of 2.4% in group B and of 3.8% in group C, respectively. The superiority of group C over group A and over group B again was relevant and statistically significant in a descriptive sense. After 2 years there was a tendency towards higher rates of vertebral and non-vertebral fractures in group A and B as compared to C. Taking both fracture types together we observed 9, 10 and 2 “osteoporotic fractures” in groups A, B and C, respectively. The comparison of group C with pooled groups A and B and with each single group gave a relevantly lower fracture rate for the combination of Alendronate and Alfacalcidol. Furthermore a lower rate of falls was observed for the combination Alendronate plus Alfacalcidol versus Alendronate + vitamin D, but not versus Alfacalcidol alone. We found 80% of the patients in the Alendronate + Alfacalcidol group free from back pain at month 24, compared to 30% in the Alendronate + vitamin D and 43% in the Alfacalcidol monotherapy group. The superiority is relevant (both tests: MW > 0.64; CI-LB > 0.56; P < 0.003). Pain decrease also occurred more rapidly in the Alendronate + Alfacalcidol group than in the other groups. In general side effects in all groups were mild, and only four cases of moderate hypercalcuria in group A and one in group C were reported, but no case of hypercalcemia was documented. In conclusion, the combination therapy with Alendronate and Alfacalcidol exhibited superiority in terms of BMD, overall fractures, rate of falls and back pain over either Alendronate in combination with plain vitamin D or Alfacalcidol alone. The overall safety profiles of the three treatment regimens were found to be not different in this study.