Reference intervals of bone turnover markers in healthy premenopausal women: results from a cross-sectional European study.

Robust validated reference intervals for bone turnover markers (BTMs) are required to assess fracture risk and effectiveness of therapy. However, there are currently limited reference intervals for BTMs in premenopausal women, especially comparing manual and automated assays. This study determined the BTM reference intervals using automated and manual assays, compared the results obtained from two different assays, and evaluated the factors that may affect BTM levels. This was a cross-sectional registry study in 194 healthy, premenopausal, European Caucasian women aged 35 to 39years from France (n=98) and Denmark (n=96). Two independent specialized laboratories, one in France (Synarc) and the other in Denmark (Nordic Bioscience), analyzed blood and urine samples from each woman for BTM levels. The type of assay used in this study significantly affected the reference intervals obtained for serum cross-linked C-terminal telopeptide of type I collagen (sCTX) and urinary cross-linked N-terminal telopeptides of type I collagen (uNTX/Cr; both P<0.001), but not for serum procollagen type I amino-terminal propeptide (PINP; P=0.28). The Serum Crosslaps® ELISA; Microtitre-plate based ELISA; Metra BAP EIA; and UniQ® PINP RIA assays yielded higher BTM reference values. The reference intervals for the BTMs, as measured with Serum ß-Crosslaps, Elecsys® 2010 Systems; VITROS® ECI System; Ostase®, Access® Immunoassay System; and Total PINP, Elecsys® 2010 Systems assays, were 0.111-0.791ng/mL for sCTX, 12.3-59.7nmol BCE/mmol creatinine for uNTX/Cr, 5.8-17.5ng/mL for bone alkaline phosphatase (ALP), and 17.3-83.4ng/mL for PINP, respectively. When measured with Serum Crosslaps® ELISA, Microtitre-plate based ELISA, Metra BAP EIA, and UniQ® PINP RIA, the reference intervals were 0.177-0.862ng/mL for sCTX, 22.6-95.7nmol BCE/mmol creatinine for uNTX/Cr, 14.8-38.8U/L for bone ALP, and 19.5-75.2ng/mL for PINP, respectively. The clinical interpretation of the BTMs of a subject should be based on comparison with a BTM reference interval, measured with the same assay method.

Bone turnover markers and bone mineral density response with risedronate therapy: relationship with fracture risk and patient adherence.

Surrogate markers of fracture risk--bone turnover markers (BTMs) and bone mineral density (BMD)--can be used to monitor treatment response. We assessed whether changes in these markers greater than the least significant change (LSC) were associated with fracture risk reduction and greater adherence. This secondary analysis of the Improving Measurements of Persistence on ACtonel Treatment (IMPACT) study--a multinational prospective, open-label, cluster-randomized study of postmenopausal women on oral risedronate 5 mg/d for 52 weeks-assessed adherence by electronic monitors. Urinary N-terminal cross-linked telopeptide of type 1 collagen (uNTX) and serum C-terminal cross-linked telopeptide of type 1 collagen (sCTX) levels were assessed at baseline and weeks 10 and 22, and BMD at baseline and week 52. Fractures were recorded as adverse events. In 2302 women, responses beyond LSC in BTMs (uNTX and sCTX) and BMD (spine only) were associated with a reduced risk of nonvertebral fractures (NVFs) and all fractures. NVF incidence was about 50% lower in patients with 30% or more of uNTX reduction at week 22 (1.6%) than in those with less than 30% reduction (3.2%, p = .015). NVFs also were reduced in patients with more than 3% spine BMD increase at 52 weeks than those with 3% or less. Responses greater than LSC in BTMs and BMD were associated with greater adherence, but there was no association between adherence and fracture outcomes at 52 weeks. Changes greater than the LSC in BTMs and BMD reflect better treatment adherence, were associated with fracture risk reduction, and identify differences in individual responsiveness to risedronate.

Monthly dosing with risedronate 50 mg on three consecutive days a month compared with daily dosing with risedronate 5 mg: a 6-month pilot study.

OBJECTIVE: Risedronate 5 mg daily significantly reduces the incidence of vertebral and non-vertebral osteoporotic fractures in postmenopausal women. We compared the efficacy and tolerability of risedronate 50 mg administered on 3 consecutive days per month, with and without a loading dose, with those of risedronate 5 mg daily in a randomized, double-blind study. METHODS: Subjects were postmenopausal women 65-80 years old with low bone mineral density (BMD) (T-score < or = -2). Subjects received risedronate 5 mg daily for 6 months (n = 48), risedronate 150 mg (50-mg doses on 3 consecutive days) monthly for 6 months (n = 50), or a loading dose of risedronate 15 mg daily for 1 month followed by 150 mg (50-mg doses on 3 consecutive days) monthly for 5 months (n = 52). RESULTS: Within 1 week, statistically significant reductions in urine N-telopeptide, the primary efficacy measure, were observed in all three groups. After 6 months, the least squares (LS) mean differences (95% confidence intervals [CI]) from the change in the 5 mg daily group (-39.88) were -3.54% (-15.71; 8.64) for the 150 mg monthly and -2.02% (-14.13;10.10) for the loading dose + 150 mg monthly groups. Mean percent changes in serum alpha-C-telopeptide, bone-specific alkaline phosphatase, and BMD, secondary efficacy measures, after 6 months were also similar for the three groups. The LS mean differences (95% CI) from the mean percent change in BMD in the 5 mg daily group (3.22%) were 0.20 (-1.15; 1.55) for the 150 mg monthly and -0.58 (-1.93; 0.76) for the loading dose + 150 mg monthly groups. The safety profile of the monthly regimens was similar to that of the 5 mg daily regimen and consistent with product labeling. CONCLUSIONS: A monthly regimen of risedronate 50 mg on 3 consecutive days per month was similar to risedronate 5 mg daily with respect to its effect in suppressing bone turnover and increasing BMD and its safety profile in women with postmenopausal osteoporosis. This study was not powered to be a confirmatory trial for non-inferiority; therefore, additional study is needed.

Underdiagnosis of vertebral fractures is a worldwide problem: the IMPACT study.

UNLABELLED: Accurate radiographic diagnosis of vertebral fractures is important. This multicenter, multinational study assessed radiographic diagnoses of vertebral fracture in 2451 postmenopausal women with osteoporosis. Comparison between local and central readings yielded a false-negative rate of 34%. Underdiagnosis of vertebral fracture is a worldwide problem. INTRODUCTION: Vertebral fractures are the most common complication of osteoporosis. Although they are associated with significant morbidity, they frequently do not come to clinical attention. Accurate radiographic diagnosis is important. MATERIALS AND METHODS: In a multicenter, multinational prospective study (the IMPACT trial), the accuracy of radiographic diagnosis of vertebral fracture was evaluated in postmenopausal women 65-80 years of age newly diagnosed with osteoporosis (based on BMD measurement). Lateral radiographs of the thoracolumbar spine were evaluated for identification of vertebral fractures, first locally and subsequently at a central reading center, using a validated semiquantitative method. False-positive and false-negative rates were calculated based on adjudicated discrepancies between the initial interpretation at the local site and the subsequent central reading, considered the "reference standard." RESULTS: Of 2451 women with an evaluable radiograph both centrally and locally, 789 (32%) had at least one vertebral fracture. Adjudicated discrepancies (n = 350 patients) between local and central readings because of undetected vertebral fracture (68%) or equivocal terminology in the local radiology report (32%) yielded a false-negative rate of 34%. CONCLUSIONS: Underdiagnosis of vertebral fractures was observed in all geographic regions (false-negative rates: North America, 45.2%; Latin America, 46.5%; Europe/South Africa/Australia, 29.5%). The false-positive rate was 5% globally. Underdiagnosis of vertebral fracture is a worldwide problem attributable in part to a lack of radiographic detection, use of ambiguous terminology in the radiology report, or both. Efforts to improve accuracy and reduce variability in terminology and interpretation may increase the effectiveness of spinal radiography for detecting vertebral fractures in patients with osteoporosis.