Bess Dawson-Hughes on behalf of the National Osteoporosis Foundation Guide Committee
Osteoporosis is an important health problem now, and the incidence of fractures and their associated costs are rising rapidly as our population ages (1). The National Osteoporosis Foundation (NOF) has estimated that by 2010, 12 million men and women in the United States will have osteoporosis and over 40 million more will have low bone mass (2). There is little controversy about whether individuals who present with osteoporosis should be considered for pharmacotherapy. Among patients with low bone mass, however, we need better discrimination of those at high risk for fracture, to maximize the benefit while limiting the risks and costs that accompany treatment. In this spirit, the NOF has collaborated with the World Health Organization (WHO) to adapt its newly developed fracture prediction algorithm (FRAX) to the U.S. population (3), performed an economic analysis to identify levels of fracture risk above which it is cost-effective to consider pharmacotherapy in this country (4), and revised the NOF Clinician’s Guide for the Prevention and Treatment of Osteoporosis (www.NOF.org). This Commentary provides a brief overview of this process, a summary of the key recommendations of the Guide, and a consideration of work that remains.
In 2003, the WHO embarked on a project to integrate information on risk factors and bone mineral density (BMD) to better predict fracture risk in men and women worldwide. The result was the release in February 2008 of a WHO Technical Report and an algorithm for assessing the 10-yr risk of a major osteoporosis-related fracture, including hip, spine, forearm, and humerus fractures (5). The clinical risk factors in the algorithm (age, body mass index, prior fragility fracture, use of oral glucocorticoids, parental history of fracture, current smoking, excess alcohol intake, secondary osteoporosis, and rheumatoid arthritis) have been validated in 60,000 men and women from 12 prospective, population-based cohorts and confirmed in other studies, including the Study of Osteoporotic Fractures and the Women’s Health Initiative.
Concurrently, a NOF committee collaborated with the WHO to calibrate the FRAX algorithm for use in the United States by incorporating U.S. hip fracture and mortality rates. The U.S.-adapted FRAX algorithm is available on the NOF website (www.NOF.org) and at www.shef.ac.uk/FRAX. The Committee also performed a cost-effectiveness analysis to estimate the levels of fracture risk above which it is reasonable to consider treatment (4). The practical implications of this analysis are described in a companion paper (3). The new NOF Clinician’s Guide (available on the NOF website at www.NOF.org) indicates 10-yr fracture risk thresholds above which it is reasonable to consider pharmacological treatment. Work is now underway to evaluate the potential impact of the Guide by estimating the number of men and women who are expected to meet the new treatment criteria.
The new Clinician’s Guide pertains to women and men of all races/ethnicities, age 50 yr and older, who are not currently on a pharmacological agent for the prevention or treatment of osteoporosis. The recommendations in the Guide are meant to serve as a reference point for decision making but are not intended to represent rigid standards. Based on clinical judgment, estimated prospective risk, patient preferences, and other factors, clinicians will need to tailor their recommendations to individual patients. The main recommendations of the NOF Guide are summarized in Table 1.
Facilitating appropriate implementation of FRAX in the United States remains an important task. The FRAX algorithm uses femoral neck T-scores (total hip is an option) based on the National Health and Nutrition Examination Survey III young Caucasian female reference values. In the United States and in many other locations, however, dual-energy x-ray absorptiometry (DXA) scans report T-scores based on same-sex reference values, and there is variation in the reference standard used for non-Caucasians. DXA T-scores on Caucasian females can be entered directly into FRAX, but corresponding T-scores for all men and for non-Caucasian women must first undergo an adjustment to the young Caucasian female reference standard before they can be used appropriately in FRAX. An effort is currently underway by the NOF and the International Osteoporosis Foundation to facilitate the needed T-score conversions. In the meantime, guidance for making these conversions is available at WWW.NOF.org. Ideally, the U.S.-adapted FRAX 10-yr fracture risk scores will eventually be available on DXA reports.
Analyses by the WHO have revealed that the impact of many secondary causes on fracture risk is mediated primarily through their effects on BMD (5). It is for this reason that checking the "secondary causes" box in FRAX does not alter the risk scores once BMD is entered into the algorithm. In contrast, the other clinical risk factors, including glucocorticoid use and rheumatoid arthritis, increase 10-yr fracture risk scores by mechanisms that are to a significant degree independent of their effects on BMD, and so their presence increases the risk scores in the presence of BMD.
作者:admin@医学,生命科学 2011-05-30 19:27