Mechanism of action study to evaluate the effect of rosiglitazone on bone in postmenopausal women with type 2 diabetes mellitus: rationale, study design and baseline characteristics.

OBJECTIVES: Post-hoc analyses have shown an increase incidence of fractures among type 2 diabetes (T2DM) patients treated with thiazolidinediones (TZDs). The mechanisms by which TZDs may be associated with increased fracture risk is not well understood. This article describes the study design and baseline characteristics for a prospective, randomized, double-blind, active-controlled trial to evaluate the effects of rosiglitazone on changes in measures of skeletal structure, surrogates of bone strength and metabolism. METHODS: Postmenopausal women without osteoporosis and diagnosed with T2DM were randomized in a double-blind design to either rosiglitazone or metformin for 52 weeks, then all subjects received open-label metformin for 24 weeks. Study endpoints included changes in bone mineral density (BMD), quantitative computed tomography (QCT), digitized hip radiography (HXR) and high resolution magnetic resonance imaging (hrMRI). Serum markers of bone metabolism and indices of glycemic control were assessed within and between treatment groups. RESULTS: A total of 226 subjects were randomized. Baseline characteristics included: age 63.8 ± 6.5 years; years postmenopausal 16.9 ± 8.4; duration of diabetes 3.5 (1.8-7.8) years; body mass index (BMI) 31.4 ± 5.9 kg/m(2); and glycated hemoglobin (HbA1c) 6.4 ± 0.65%. At baseline, mean T-scores were -0.95 ± 0.91 at the femoral neck, -0.02 ± 0.97 at the total hip and -0.55 ± 1.25 at the total spine. Since there are no well recognized techniques to determine bone mass and structure at the distal limbs (cortical bone sites where fractures were reported in RSG subjects), using the femoral neck as a surrogate for these areas may be a potential limitation of the study. CONCLUSION: This is the first randomized trial utilizing multiple techniques to evaluate bone mass, structure, serum markers of bone remodeling, and potential reversibility of changes after discontinuation of rosiglitazone. This study will provide information about RSG bone effects in a population of postmenopausal women at risk for bone loss and subsequent fracture. CLINICALTRIALSGOV NUMBER: NCT00679939.

Risk factors for prediction of inadequate response to antiresorptives.

Some patients sustain fractures while on antiresorptives. Whether this represents an inadequate response (IR) to treatment or a chance event has not been elucidated. We performed a study to identify which patients are more likely to fracture while on treatment. This is a multicentric, cross-sectional study of postmenopausal women on antiresorptives for osteoporosis in 12 Spanish hospitals, classified as adequate responders (ARs) if on treatment with antiresorptives for 5 years with no incident fractures or inadequate responders (IRs) if an incident fracture occurred between 1 and 5 years on treatment. Poor compliance, secondary osteoporosis, and previous anti-osteoporosis treatment other than the assessed were exclusion criteria. Clinical, demographic, analytical, dual-energy X-ray absorptiometry (DXA) variables, and proximal femur structure analysis (ImaTx™) and structural/fractal analyses of distal radius were performed. A total of 179 women (76 IRs; mean (SD): age 68.2 (9.0) years; 103 ARs, age 68.5 (7.9) years) were included. History of prior fracture (p = 0.005), two or more falls in the previous year (p = 0.032), low lumbar spine bone mineral density (BMD) (p = 0.02), 25 hydroxyvitamin D (p = 0.017), and hip ImaTx fracture load index (p = 0.004) were associated with IR. In the logistic regression models a fracture before treatment (odds ratio [OR], 3.60; 95% confidence interval [CI], 1.47-8.82; p = 0.005) and levels of 25 hydroxyvitamin D below 20 ng/mL (OR, 3.89; 95% CI, 1.55-9.77; p = 0.004) significantly increased risk for IR, while increased ImaTx fracture load (OR, 0.96; 95% CI, 0.93-0.99; p = 0.006; per every 100 units) was protective, although the latter became not significant when all three variables were fitted into the model. Therefore, we can infer that severity of the disease, with microarchitectural and structure deterioration, as shown by previous fracture and hip analysis, and low levels of 25 hydroxy vitamin D carry higher risk of inadequate response to antiresorptives. More potent regimes should be developed and adequate supplementation implemented to solve this problem.

Teriparatide, vitamin D, and calcium healed bilateral subtrochanteric stress fractures in a postmenopausal woman with a 13-year history of continuous alendronate therapy.

BACKGROUND: Oral bisphosphonates comprise the most widely prescribed class of antiosteoporotic drugs. Recent reports, however, propose a link between prolonged bisphosphonate use and atypical, low-energy, subtrochanteric fractures. OBJECTIVES: The aim was to describe the clinical course of a patient treated long-term with alendronate who developed subtrochanteric stress fractures and to propose a hypothesis to explain teriparatide's potential contribution in healing the patient's stress fractures. RESULTS: Magnetic resonance imaging (MRI) showed classical bilateral stress fractures of the mid-femora. Baseline serum 25-hydroxyvitamin D(3) was low; bone-specific alkaline phosphatase was slightly increased; serum carboxyterminal cross-linking telopeptide of bone collagen and urine aminoterminal cross-linking telopeptide of bone collagen were low to normal, as was serum osteocalcin. Dual-energy x-ray absorptiometry showed osteopenic vertebral bone mineral density and osteoporotic hip values. Treatment with large doses of oral vitamin D increased serum 25-hydroxyvitamin D(3) to normal within 2 months, after which it remained in the normal range with maintenance doses. Thigh pain, present as an initial symptom, intensified, and the MRI appearance of the fractures worsened. Teriparatide treatment commenced, and 6 months later, a repeat MRI showed decreased edema at the fracture sites with faint cortical bridging. Thigh pain and lower limb weakness disappeared over the next year, and complete fracture healing was established (MRI). CONCLUSIONS: Based upon the chronology of fracture healing in our patient and published evidence that teriparatide heals stress fractures in a rat model, we think that teriparatide was probably primary in this patient's positive response to therapy, with calcium, vitamin D therapy, and alendronate discontinuation playing secondary roles.

Prevention of osteoporosis and uterine effects in postmenopausal women taking raloxifene for 5 years.

OBJECTIVE: Raloxifene hydrochloride (60 mg/day) is a selective estrogen receptor modulator indicated for the prevention and treatment of postmenopausal osteoporosis. Raloxifene treatment for 3 years increases bone mineral density (BMD) and, unlike tamoxifen (a triphenylethylene selective estrogen receptor modulator), does not stimulate the endometrium in healthy postmenopausal women. The effect of longer duration of treatment with raloxifene is not known. Therefore, the main objectives of these analyses are (1) to compare the effect of 5 years of treatment with raloxifene (60 mg/day) with placebo in terms of the likelihood of developing osteoporosis and (2) to evaluate the effect of 5 years of raloxifene treatment on the endometrium and incidence of vaginal bleeding. DESIGN: The current analyses include integrated data from two identically designed, prospective, double-blinded trials including postmenopausal women (mean age, 55 years) randomly assigned to either placebo (n = 143) or raloxifene (60 mg/day; n = 185). Osteoporosis and osteopenia were diagnosed according to World Health Organization criteria, using the manufacturer's database for the lumbar spine and the National Health and Nutrition Examination Survey's 1998 reference base for the hip. Endometrial thickness was determined using transvaginal ultrasonography. Clinical diagnoses of endometrial hyperplasia or endometrial cancer were confirmed by blinded review of histopathology reports. RESULTS: Compared with the case of placebo, raloxifene treatment for 5 years reduced bone turnover markers (osteocalcin: -10.9%, P < 0.001; bone-specific alkaline phosphatase: -7.2%, P = 0.042; urinary C-telopeptide: -11.1%, P = 0.034) and was associated with increased BMD in the lumbar spine (2.8%; P < 0.001) and total hip BMD (2.6%; P < 0.001). Women taking raloxifene were less likely to develop osteoporosis (relative risk [RR] for raloxifene v placebo: 0.13; 95% CI: 0.00, 0.37; P = 0.001) or osteopenia (RR: 0.23; 95% CI: 0.00, 0.81; P = 0.038) at the lumbar spine and were more likely to convert to normal BMD status at the lumbar spine (RR: 4.01; 95% CI: 1.34, 11.23; P = 0.043) and total hip (RR: 3.92; 95% CI: 1.12,14.27; P = 0.011) at 5 years, compared with the case of placebo. Raloxifene also significantly reduced total cholesterol (-5.5%; P < 0.001) and low-density lipoprotein cholesterol (-8.7%; P < 0.001), compared with the case of placebo. No significant changes in high-density lipoprotein cholesterol (P = 0.257) or triglycerides (P = 0.620) were detected. Incidence of hot flashes was higher among women taking raloxifene compared with those taking placebo [raloxifene, 47 (28.8%); placebo, 21 (16.8%); P = 0.017]. Women taking placebo or raloxifene reported a similar incidence of vaginal bleeding (P = 0.999) or of mean endometrial thickness of more than 5 mm at baseline and at each visit, up to the 5-year endpoint (P >/= 0.349). No diagnoses of endometrial hyperplasia or endometrial cancer were made in either treatment group. CONCLUSIONS: Five years of raloxifene treatment in healthy postmenopausal women preserves BMD, significantly reduces the likelihood of development of osteoporosis, and was not associated with an increased rate of vaginal bleeding, endometrial hyperplasia, or endometrial carcinoma, compared with the case of placebo.