Risedronate versus alendronate for osteoporosis

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The review of many studies concludes that both risedronate versus

alendronate are effective but the former may be better.

Osteoporosis is an increased risk for CRers, some are suggesting strongly.

Fractures have been reported.

Cheers, Al.

Analysis of 1-year Vertebral Fracture Risk Reduction Data in Treatments for

Osteoporosis.

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Southern Med J Volume 96(5), May 2003, 478-485

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The number needed to treat (NNT) is an increasingly popular indicator of

fracture efficacy and reflects the number of

patients that need to be treated to prevent one event. 25 In a therapeutic

trial, the NNT is the inverse of the absolute benefit of

intervention, that is, the difference between the proportion of events in the

control group (Pc) and the proportion of events in the

intervention group (Pi): NNT = 1 ÷ (control group [Pc] - intervention group

[Pi]).

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Postmenopausal Osteoporosis

Risedronate

Risedronate is approved for both prevention and treatment of

postmenopausal and glucocorticoid-induced osteoporosis and is

available in both once-daily (5 mg) and once-weekly (35 mg) formulations. 42

In randomized studies of postmenopausal women with

osteoporosis, risedronate reduced the risk of radiologically detected

vertebral fracture within 1 year (Table 1). The Vertebral Efficacy

with Risedronate Therapy (VERT) studies evaluated the effect of risedronate

on fracture risk in postmenopausal women with

osteoporosis. The North American study (VERT-NA) enrolled 2,458 patients with

at least 2 vertebral fractures at baseline or 1 vertebral

fracture and lumbar spine T-score <=-2 at baseline 28; the multinational

study (VERT-MN) assessed 1,226 patients with at least 2

vertebral fractures at baseline. 27 These studies prospectively assessed

1-year vertebral fracture risk reduction. Risedronate 5 mg/d

significantly reduced the risk of morphometric vertebral fractures by 65 and

61% (NNT = 25 and 21) after 1 year of treatment in the

VERT-NA and VERT-MN studies, respectively (Table 1).

In an abstract that reported the results of a combined analysis of the VERT

studies, risedronate 5 mg/d produced a statistically

significant 69% reduction in the risk of clinical vertebral fractures after 1

year among risedronate 5 mg/d recipients. 43 In addition, this

analysis found a significant reduction in the risk of vertebral fractures

diagnosed clinically after 6 months of therapy (P < 0.01). 43 A

recent abstract containing the results of a meta-analysis of 5 trials

(including the VERT studies) reported that risedronate 5 mg/d

reduced the 1-year risk of new morphometric vertebral fractures by 64% (NNT =

21). 44

The large Hip Intervention Program (HIP) study assessed the effect of

risedronate on 3-year hip fracture risk in 9,331 women aged

70 to 79 years with established osteoporosis by WHO criteria (T score <=-2.5)

and in women at least 80 years of age with at least one

nonskeletal risk factor for hip fracture or low BMD at the femoral neck. 45

In a post hoc analysis of HIP study data (in abstract form),

treatment with risedronate 5 mg/d significantly reduced the 1-year risk of

new morphometric vertebral fractures by 55% (NNT = 37). 46

Alendronate

Alendronate is approved for prevention and treatment of postmenopausal

osteoporosis and for treatment of

glucocorticoid-induced osteoporosis and is available in the following

formulations: for the treatment of postmenopausal women once

daily (10 mg) and once weekly (70 mg) and for prevention in postmenopausal

women once daily (5 mg) and once weekly (35 mg). 47

Most of the alendronate studies reported vertebral fracture risk reduction

after 3 or more years of treatment. In an early Phase III study,

lateral spine radiographs were done after 1, 2, and 3 years of therapy to

detect vertebral fractures and progression of vertebral

deformities; however, only 3-year fracture risk data were reported. 48 The

Fracture Intervention Trial (FIT) studied the effect of

alendronate on the incidence of vertebral and nonvertebral fractures in

postmenopausal women with low femoral neck BMD using the

Hologic database (T-score at least -2.0 and at least one vertebral fracture)

38 or T-score at least -2.0 and no vertebral fracture). 39

When the data were reanalyzed using T-scores derived from the Third National

Health and Nutrition Examination Survey (NHANES

III), the threshold T-score for inclusion in FIT was <=-1.6. 49

Efficacy data were reported in two separate arms of the FIT trial, a 3-year

arm in 2,027 patients with at least 1 vertebral fracture at

baseline (FIT 1) 38 and a 4-year arm in 4,432 patients with no vertebral

fractures at baseline (FIT 2). 39 The dose of alendronate used in

these studies was 5 mg/d for the first 2 years, then 10 mg/d for the

subsequent years. Spinal radiographs were obtained at 2 and 3

years after randomization in FIT 1 and at 4 years in FIT 2; therefore, 1-year

morphometric fracture data are not available for either

study. Two post hoc analyses of FIT data reported a significant reduction in

the 1-year risk of new clinical fractures with alendronate

in women with confirmed postmenopausal osteoporosis (Table 1). 49,50 Clinical

vertebral fractures were defined as those that came to

the medical attention of the investigators (most often because of back pain).

Fracture incidence was not reported in these analyses;

therefore, absolute risk reduction and NNT data are not available.

Another post hoc analysis using alendronate reported a significant 100% (P

= 0.044) reduction in the risk of multiple clinical

fractures at 6 months. 50 One problem with using multiple vertebral fractures

as an outcome is that it ignores the first new vertebral

fracture during the observation period. In the case of the 6-month clinical

fracture data described above, this means that patients had

already experienced 1 clinical vertebral fracture (and perhaps multiple

fractures had they been assessed morphometrically). Similar

clinical vertebral fracture results were obtained in a third analysis of FIT

data presented in abstract form. 51 In this analysis, the relative

risk of new clinical vertebral fractures was reduced by 68% in 942 patients

who had a morphometrically defined vertebral fracture at

baseline and by 54% in 2,799 patients who did not have a preexisting

vertebral fracture (P values not available).

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