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Background: Use of Teriparatide (PTH) with Denosumab (Dmab) have shown to have a synergistic effect on the bone mineral density (BMD) of both Hip and Spine 1 because Dmab completely inhibits the PTH induced bone resorption and does not interfere with the bone formation.
Objectives: Since PTH has a limited period of approved use, a short term (6 months) use of PTH in combination with Dmab followed by continued use of Dmab may show a sustained synergistic effect of the combination.
Methods: The BMD trends from real time data from a central dual-energy x-ray absorptiometry (DXA) at our centre in India was studied retrospectively to see if the effect was sustained. Women with postmenopausal osteoporosis who were treated with a combination of Dmab 60 mg via subcutaneous injection (sc) at 6 monthly interval along with PTH 20 mcg sc daily for the first 6 months (Combo), followed by Dmab alone for the next six months were inculded in the study group. Average BMD at L2, L3 and L4 (sp BMD), and Right and Left Hip (hip BMD) were studied from before treatment (a BMD), after the Combo treatment (b BMD) and after 6 months of the second injection of Dmab (c BMD). The mean percentage trend change between a-b BMD and b-c BMD were evaluated. Out of the patients treated with the protocol, 25 were randomly chosen for the retrospective analysis. The least significant change (LSC) 2 from a single centre DXA was used to validate the findings.
Results: The percentage change after the treatment for 6 months with the Combo was found to be 5.22% in the Spine (LSC= 2.6%)
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and 4.13% in the hip (LSC=3.6%)
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. The trend after use of Dmab alone was 5.39% in the spine and 2.93% in the hip showing sustained synergistic effect of the Combo for at least 6 months with the use of Dmab alone. The effect was more profound in the spine than the hip. A p>0.05 was considered statistically significant.
Percentage BMD changes
| BMD trend (n=25) | sp BMD (LSC – 2.6%) | hip BMD (LSC – 3.6%) |
|---|---|---|
| a-b BMD | 5.22% | 4.13% |
| b-c BMD | 5.39% | 2.93% |
sp BMD - Mean of L2,L3 & L4 Spine BMD, hip BMD - Mean of Right and Left Hip BMD, a-b BMD - Percent change in BMD from before treatment to 6 months of PTH & Dmab, b-c BMD -Percentage change in BMD form after 6 of Dmab & PTH to next 6 mths Dmab alone and LSC – Least significant change from a single DXA machine.
Conclusion: These findings suggest that a short term combination of Dmab and PTH for 6 months followed by Dmab alone shows sustained synergistic effect on the BMD trend which was more profound in the spine than the hip.
This would help in judicious and cost effective utilisation of the limited period of PTH use.
REFERENCES:
[1]Tsai JN et al: Teriparatide and denosumab, alone or combined, in women with postmenopausal osteoporosis: the DATA study randomised trial. Lancet. 2013; 382: 50-56
[2]Shepherd JA1, Lu Y. A generalized least significant change for individuals measured on different DXA systems.
Disclosure of Interests: None declared