Screening points for a peripheral densitometer of the calcaneum for the diagnosis of osteoporosis

Summary We calculate specific triage thresholds for the PIXI-LUNAR heel densitometer to give a 90% specificity for osteoporosis and normal bone mineral density (BMD) at the hip or spine. 693 women aged 30-93 years (mean age 58.2 ± 9.6 years) referred for osteoporosis study, underwent hip and spine BMD measurements (HOLOGIC) by dual energy X-ray absortiometry (DXA), also had a peripheral heel DXA densitometry (PIXI-LUNAR). The os calcis T-scores for all woman were subjected to a receiver operator characteristic (ROC) analysis with the definition of osteoporosis (T-score ≤ -2.5) and BMD normal (T-score > -1) made at the the lumbar spine or femoral neck. Patients with a heel T-score of above +0.6 are very likely to have normal bone density on axial densitometry, whilst patients with heel T-score of below -1.3 are very likely to have osteoporosis at the hip or spine. Only patients whose measurements lie between the thresholds should be referred for axial DXA.