Fig. 1

Training and validation of two-stage diagnostic algorithms for detection of impaired skeletal health and discrimination of early-stage osteoarthritis (eOA), rheumatoid arthritis (RA) and other inflammatory joint disease. a Training set and test set study groups for detection of impaired skeletal health. A receiver operating characteristic (ROC) curve is given for the training set. The area under the ROC curve (AUROC) was 0.99 (95 % confidence interval 0.97–1.00). Comparators were eOA + early RA (eRA) + non-RA versus healthy controls. A random outcome is 0.50. b Training set and test set study groups for discrimination of eOA, eRA and non-RA. ROC curves are given for the training set with AUROC and confidence intervals: eOA, 0.98 (0.96–1.00); eRA, 0.91 (0.81–1.00); and non-RA, 0.68 (0.50–0.86). Comparators were eOA, eRA or non-RA versus other early-stage arthritic diseases combined. A random outcome is 0.33