Development and validation of the Osteoporosis Risk Assessment Instrument to facilitate selection of women for bone densitometry

Background: Although mass screening for osteoporosis is not recommended amo ng postmenopausal women, there is no consensus on which women should underg o testing for low bone mineral density. The objective of this study was to develop and validate a clinical tool to help clinicians identify which wome n are at increased risk for osteoporosis and should therefore undergo furth er testing with bone densitometry. Methods: Using Ontario baseline data from the Canadian Multicentre Osteopor osis Study, we identified all cognitively normal women aged 45 years or mor e who had undergone testing with dual-energy x-ray absorptiometry (DXA) at both the femoral neck and the lumbar spine (L1-L4). Participants who had a previous diagnosis of osteoporosis or were taking bone active medication ot her than ovarian hormones were excluded. The main outcome measure was low b one mineral density (T score of 2 or more standard deviations below the mea n: for young Canadian women) at either the femoral neck or the lumbar spine . Logistic regression analysis and receiver operating characteristic (ROC) analysis were used to identify the simplest algorithm that would identify w omen at increased risk for low bone mineral density. Results: The study population comprised 1376 women, of whom 926 were alloca ted to the development of the tool and 450 to its validation. A simple algo rithm based on age, weight and current estrogen use (yes or no) was develop ed. Validation of this 3-item Osteoporosis Risk Assessment Instrument (ORAI ) showed that the tool had a sensitivity of 93.3% (95% confidence interval ICI] 86.3%-97.0%) and a specificity of 46.4% (95% CI 41.0%-51.8%) for selec ting women with low bone mineral density. The sensitivity of the instrument for selecting women with osteoporosis was 94.4% (95% CI 83.7%-98.6%), Use of the ORAI represented a 38.7% reduction in DXA testing compared with scre ening all women in our study. Interpretation: The ORAI accurately identifies the vast majority of women l ikely to have low bone mineral density and is effective in substantially de creasing the need for all women to undergo DXA testing.