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Menopause Live - IMS Updates
InFocus

Date of release: 20 September, 2010

An update on screening for osteoporosis


A recent review by Nelson and colleagues for the US Preventive Services Task Force [1] updates evidence on screening for osteoporosis since the 2002 report by the same group. The purposes of the review were to determine: the effectiveness and harms of osteoporosis screening in reducing fractures for men and postmenopausal women without known previous fractures; the performance of risk assessment instruments and bone measurement tests in identifying persons with osteoporosis; optimal screening intervals; and the efficacy and harms of medications to reduce primary fractures. The data sources are the Cochrane Central Register of Controlled Trials and the Cochrane Database of Systematic Reviews (through the fourth quarter of 2009), and MEDLINE (January 2001 to December 2009). The study selection included randomized, controlled trials of screening or medications with fracture outcomes published in English, performance studies of validated risk-assessment instruments and systematic reviews and population-based studies of bone measurement tests or medication harms.


 


The main conclusions of the study are:


(1) Several risk-assessment instruments have been developed and validated. They are modest predictors of low bone density or fracture. Simple models predict as well as complex ones and none demonstrates superiority over the others.


(2) Dual X-ray absorptiometry (DXA) is not a perfect predictor of fractures but, for each standard deviation reduction in femoral neck bone mineral density (BMD), the hazard ratio for various fracture outcomes increases to similar levels for men and women.


(3) Calcaneal ultrasound predicts fractures of the femoral neck, hip, or spine, although variation exists across studies and correlation with DXA is low. The clinical application is unknown.


(4) No studies addressing the frequency of follow-up DXA examinations were found. A single study found that repeating a BMD measurement up to 8 years after an initial measurement does not significantly improve predictive performance for non-vertebral, hip, or vertebral fractures.


(5) In women, bisphosphonates, PTH, raloxifene and estrogen reduce vertebral fractures. Bisphosphonates reduce non-vertebral fractures only in sensitivity analyses. Medications are effective for BMD T-scores of -2.5 or less. 


(6) Serious gastrointestinal events, atrial fibrillation, osteonecrosis of the jaw, severe musculoskeletal pain and esophageal cancer have been reported for bisphosphonates, but the incidence and degree of risk are difficult to estimate for those using them for prevention; raloxifene and estrogen increase thromboembolic events; estrogen increases stroke; and estrogen with progestin increases coronary heart disease and breast cancer.

Comment

The efficacy and potential harm of population screening methods need to be measured according to evidence-based principles at regular intervals. Recent examples are controversial findings regarding mammography and PSA screening for prostate cancer.
 
The present report is not controversial and should have no dramatic impact on present clinical practice. It reinforces the concept that, without any direct evidence supporting population-based screening, we should concentrate on a case-specific approach by identifying and treating the individual at risk. The report reiterates the validity of various risk factors for fracture such as low BMD, age, family history and medications, but concludes that simple models are as effective as the more complex models such as FRAX. The role of DXA as the gold standard in BMD estimation is supported by the report. This view is based not only on a validation of the correlation between lowered BMD and fracture but also because DXA-derived BMD values were used as selection criteria in most fracture prevention trials. The report does not recommend any threshold risk estimation for intervention or DXA screening or frequency of screening. It is my impression that guidelines for screening for risk of fracture facture will continue to be country-specific, based on the local prevalence of fractures and resources available to combat the disease. 
 
It is reassuring to know that the evidence for the prevention of vertebral fractures by various medications is robust but, with the exception of estrogen, they are only effective in the presence of a BMD T-score of lower than -2.5. It is sobering to be reminded again that the evidence on the prevention of hip fracture is not as robust or convincing. The risks associated with the various medications yield no surprises and are reassuring regarding recent concerns about the bisphosphonates (osteonecrosis of the jaw and subtrochanteric femur fractures). The possible harm of hormone replacement therapy is overstated in view of the evidence presented, but this comes as no surprise. Reading of the original text is advised for everyone with a special interest in osteoporosis.

Comentario

Tobie de Villiers
Consultant Gynaecologist, Panorama MediClinic, Cape Town, South Africa

    References

  1. Nelson HD, Haney EM, Dana T, et al. Screening for osteoporosis: an update for the U.S. Preventive Services Task Force. Ann Intern Med 2010;153:99-111.
    http://www.ncbi.nlm.nih.gov/pubmed/20621892