David B. Karpf

Randomised trial of effect of alendronate on risk of fracture in women with existing vertebral fractures

BACKGROUND Previous studies have shown that alendronate can increase bone mineral density (BMD) and prevent radiographically defined (morphometric) vertebral fractures. The Fracture Intervention Trial aimed to investigate the effect of alendronate on the risk of morphometric as well as clinically evident fractures in postmenopausal women with low bone mass. METHODS Women aged 55-81 with low femoral-neck BMD were enrolled in two study groups based on presence or absence of an existing vertebral fracture. Results for women with at least one vertebral fracture at baseline are reported here. 2027 women were randomly assigned placebo (1005) or alendronate (1022) and followed up for 36 months. The dose of alendronate (initially 5 mg daily) was increased (to 10 mg daily) at 24 months, with maintenance of the double blind. Lateral spine radiography was done at baseline and at 24 and 36 months. New vertebral fractures, the primary endpoint, were defined by morphometry as a decrease of 20% (and at least 4 mm) in at least one vertebral height between the baseline and latest follow-up radiograph. Non-spine clinical fractures were confirmed by radiographic reports. New symptomatic vertebral fractures were based on self-report and confirmed by radiography. FINDINGS Follow-up radiographs were obtained for 1946 women (98% of surviving participants). 78 (8.0%) of women in the alendronate group had one or more new morphometric vertebral fractures compared with 145 (15.0%) in the placebo group (relative risk 0.53 [95% Cl 0.41-0.68]). For clinically apparent vertebral fractures, the corresponding numbers were 23 (2.3%) alendronate and 50 (5.0%) placebo (relative hazard 0.45 [0.27-0.72]). The risk of any clinical fracture, the main secondary endpoint, was lower in the alendronate than in the placebo group (139 [13.6%] vs 183 [18.2%]; relative hazard 0.72 [0.58-0.90]). The relative hazards for hip fracture and wrist fracture for alendronate versus placebo were 0.49 (0.23-0.99) and 0.52 (0.31-0.87). There was no significant difference between the groups in numbers of adverse experiences, including upper-gastrointestinal disorders. INTERPRETATION We conclude that among women with low bone mass and existing vertebral fractures, alendronate is well tolerated and substantially reduces the frequency of morphometric and clinical vertebral fractures, as well as other clinical fractures.

Effect of Oral Alendronate on Bone Mineral Density and the Incidence of Fractures in Postmenopausal Osteoporosis

BACKGROUND Postmenopausal osteoporosis is a serious health problem, and additional treatments are needed. METHODS We studied the effects of oral alendronate, an aminobisphosphonate, on bone mineral density and the incidence of fractures and height loss in 994 women with postmenopausal osteoporosis. The women were treated with placebo or alendronate (5 or 10 mg daily for three years, or 20 mg for two years followed by 5 mg for one year); all the women received 500 mg of calcium daily. Bone mineral density was measured by dual-energy x-ray absorptiometry. The occurrence of new vertebral fractures and the progression of vertebral deformities were determined by an analysis of digitized radiographs, and loss of height was determined by sequential height measurements. RESULTS The women receiving alendronate had significant, progressive increases in bone mineral density at all skeletal sites, whereas those receiving placebo had decreases in bone mineral density. At three years, the mean (+/- SE) differences in bone mineral density between the women receiving 10 mg of alendronate daily and those receiving placebo were 8.8 +/- 0.4 percent in the spine, 5.9 +/- 0.5 percent in the femoral neck, 7.8 +/- 0.6 percent in the trochanter, and 2.5 +/- 0.3 percent in the total body (P < 0.001 for all comparisons). The 5-mg dose was less effective than the 10-mg dose, and the regimen of 20 mg followed by 5 mg was similar in efficacy to the 10-mg dose. Overall, treatment with alendronate was associated with a 48 percent reduction in the proportion of women with new vertebral fractures (3.2 percent, vs. 6.2 percent in the placebo group; P = 0.03), a decreased progression of vertebral deformities (33 percent, vs. 41 percent in the placebo group; P = 0.028), and a reduced loss of height (P = 0.005) and was well tolerated. CONCLUSIONS Daily treatment with alendronate progressively increases the bone mass in the spine, hip, and total body and reduces the incidence of vertebral fractures, the progression of vertebral deformities, and height loss in postmenopausal women with osteoporosis.

Improvement in spine bone density and reduction in risk of vertebral fractures during treatment with antiresorptive drugs

PURPOSE To estimate how much the improvement in bone mass accounts for the reduction in risk of vertebral fracture that has been observed in randomized trials of antiresorptive treatments for osteoporosis. METHODS After a systematic search, we conducted a meta-analysis of 12 trials to describe the relation between improvement in spine bone mineral density and reduction in risk of vertebral fracture in postmenopausal women. We also used logistic models to estimate the proportion of the reduction in risk of vertebral fracture observed with alendronate in the Fracture Intervention Trial that was due to improvement in bone mineral density. RESULTS Across the 12 trials, a 1% improvement in spine bone mineral density was associated with a 0.03 decrease (95% confidence interval [CI]: 0.02 to 0.05) in the relative risk (RR) of vertebral fracture. The reductions in risk were greater than predicted from improvement in bone mineral density; for example, the model estimated that treatments predicted to reduce fracture risk by 20% (RR = 0.80), based on improvement in bone mineral density, actually reduce the risk of fracture by about 45% (RR = 0.55). In the Fracture Intervention Trial, improvement in spine bone mineral density explained 16% (95% CI: 11% to 27%) of the reduction in the risk of vertebral fracture with alendronate. CONCLUSION Improvement in spine bone mineral density during treatment with antiresorptive drugs accounts for a predictable but small part of the observed reduction in the risk of vertebral fracture.

Design of the Fracture Intervention Trial

The Fracture Intervention Trial (FIT) is a randomized, double-masked, placebo-controlled trial designed to test the hypothesis that alendronate, an amino-bisphosphonate, will reduce the rate of fractures in women aged 55–80 years with low hip bone marrow density (<0.68 gm/cm2 at the femoral neck). It is being conducted at 11 clinical centers around the United States with a coordinating center at UC San Francisco. The goal was to randomize 6000 women. When recruitment was completed (in May 1993), 6457 women had been randomized, amounting to 108% of goal. The women were assigned to one of two substudies. The first (Vertebral Deformity study) includes 2023 women who have at least one vertebral deformity, and will test the hypothesis that alendronate reduces the rate of new vertebral deformities during 3 years of follow-up. This substudy has a power of 0.90 to detect a 32% reduction in the incidence of new vertebral deformities, assuming a 6.5% annual incidence of new vertebral deformities in the placebo group. The second study (Clinical Fracture study) includes 4434 women without vertebral deformities at baseline and will test the hypothesis that alendronate reduces the rate of clinically recognized fractures of all types over an average of 4.25 years of follow-up. This substudy has a 0.90 power to detect a 25% reduction in the rate of all clinical fractures, assuming 4% annual incidence in the placebo group. To our knowledge, this is the largest prospective, randomized, controlled study undertaken to determine the effectiveness of a treatment in reducing the risk of fractures in postmenopausal women.

MBX-8025, A Novel Peroxisome Proliferator Receptor-δ Agonist: Lipid and Other Metabolic Effects in Dyslipidemic Overweight Patients Treated with and without Atorvastatin

CONTEXT Preclinical and clinical studies suggest that peroxisome proliferator-activated receptor (PPAR)-δ agonists favorably affect multiple metabolic parameters that are otherwise proatherogenic, many that are not optimally managed with statins alone. OBJECTIVE The aim of this study was to evaluate the effects of MBX-8025 (a novel PPAR-δ agonist) on lipid and other metabolic parameters associated with increased atherosclerotic risk, administered alone and in combination with atorvastatin. DESIGN AND SETTING This was a randomized, double-blind, placebo-controlled, parallel group proof-of-concept study conducted at 30 U.S. research sites. PARTICIPANTS This study evaluated 181 overweight men and women with mixed dyslipidemia. INTERVENTION(S) Subjects were administered once daily placebo, atorvastatin 20 mg, or MBX-8025 at 50 or 100 mg alone or combined with atorvastatin for 8 wk. MAIN OUTCOME MEASURES The main efficacy measures included change from baseline in apolipoprotein B-100, lipid levels, high-sensitivity C-reactive protein, and additional metabolic parameters, as well as the effect on the metabolic syndrome and LDL particle size. RESULTS Compared to placebo, MBX-8025 alone and in combination with atorvastatin significantly (P < 0.05) reduced apolipoprotein B-100 20-38%, LDL 18-43%, triglycerides 26-30%, non-high-density lipoprotein cholesterol 18-41%, free fatty acids 16-28%, and high-sensitivity C-reactive protein 43-72%; it raised high-density lipoprotein cholesterol 1-12% and also reduced the number of patients with the metabolic syndrome and a preponderance of small LDL particles. MBX-8025 was safe and generally well-tolerated. MBX-8025 also reduced liver enzyme levels. CONCLUSION MBX-8025, a novel PPAR-δ agonist, favorably affected multiple metabolic parameters with and without atorvastatin. A more complete understanding of MBX-8025 requires a larger future study.

Effects of the PPAR-δ agonist MBX-8025 on atherogenic dyslipidemia.

OBJECTIVE Determine the effects of treatment with a selective PPAR-δ agonist±statin on plasma lipoprotein subfractions in dyslipidemic individuals. METHODS Ion mobility analysis was used to measure plasma concentrations of subfractions of the full spectrum of lipoprotein particles in 166 overweight or obese dyslipidemic individuals treated with the PPAR-δ agonist MBX-8025 (50 and 100 mg/d)±atorvastatin (20 mg/d) in an 8-week randomized parallel arm double blind placebo controlled trial. RESULTS MBX-8025 at both doses resulted in reductions of small plus very small LDL particles and increased levels of large LDL, with a concomitant reduction in large VLDL, and an increase in LDL peak diameter. This translated to reversal of the small dense LDL phenotype (LDL pattern B) in ∼90% of the participants. Modest increases in HDL particles were confined to the smaller HDL fractions. Atorvastatin monotherapy resulted in reductions in particles across the VLDL-IDL-LDL spectrum, with a significantly smaller reduction in small and very small LDL vs. MBX-8025 100 mg/d (-24.5±5.3% vs. -47.8±4.9%), and, in combination with MBX-8025, a reversal of the increase in large LDL. CONCLUSION PPAR-δ and statin therapies have complementary effects in improving lipoprotein subfractions associated with atherogenic dyslipidemia.