ECTS Abstracts (2015) 1 P368

Comparison of treatment responder rates for three oral bisphosphonates: the TRIO study

Margaret Paggiosi1, Nicola Peel2, Eugene McCloskey1, Jennifer Walsh1 & Richard Eastell1


1The University of Sheffield, Sheffield, South Yorkshire, UK; 2Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, South Yorkshire, UK.


Bone mineral density (BMD) is used to assess the efficacy of bisphosphonate treatment in the individual patient, however it is unclear whether the response rate is similar for all oral bisphosphonates. The TRIO study is a randomised, open-label, parallel, controlled trial of three bisphosphonates, orally administered at their licensed dose for two years. We recruited postmenopausal women (n=172, ages 53-84 years) with a BMD T-score, by DXA, of <-2.5 at the spine and/or total hip, or of <-1.0 plus a previous low trauma fracture. Women were randomised to receive one of three bisphosphonates, either alendronate 70 mg once weekly, risedronate 35 mg once weekly, or ibandronate 150 mg once monthly, together with calcium (1200 mg) and vitamin D (800 IU) daily supplements. Lumbar spine and total hip BMD were measured at baseline and weeks 12 (in duplicate), 48 and 96. We calculated changes in lumbar spine and total hip BMD between baseline and weeks 12, 48 and 96 for each individual. The duplicate week 12 results were used to calculate the least significant change (LSC) for lumbar spine (4.4%) and total hip BMD (4.2%). Women could be classified as treatment responders if their individual BMD increase was greater than the site-specific LSC. Differences in the number of responders by weeks 12, 48 and 96 were examined using chi-squared tests (Table 1). Even though the LSCs were similar, lumbar spine BMD was able to identify more treatment responders than total hip BMD. We found that the number of treatment responders was dependent on the bisphosphonate type. By week 96, more women had responded to alendronate than ibandronate and risedronate.

Table 1 The proportion and percentage of responders by treatment duration and bisphosphonate type.
Week 12Week 48Week 96
Proportion of responders (n/group n)Responders (%) Proportion of responders (n/group n)Responders (%) Proportion of responders (n/group n)Responders (%)
Lumbar spine
Ibandronate10/4920.424/45a53.320/29b69.0
Alendronate11/3520.025/50a50.029/34b85.3
Risedronate7/14.912/46a26.13/30b43.3
All28/15218.461/14143.362/9366.7
Total hip
Ibandronate6/4812.510/4422.79/28c32.1
Alendronate10/5518.212/5024.018/34c52.9
Risedronate3/486.34/468.76/30c20.0
All19/15212.526/14118.433/9235.9
Number of responders is significantly different between bisphosphonates by chi-squared testing; a (p=0.02), b (p=0.002) and c (p=0.02).Number of responders is significantly different between bisphosphonates by chi-squared testing; a (p=0.02), b (p=0.002) and c (p=0.02).

Disclosure: The authors declared no competing interests. This work was funded by Warner Chilcott.

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