Accuracy of the algorithm in the training sample by step
| Step | Sensitivity (95% CI) | Specificity (95% CI) |
|---|---|---|
| Step 1: RA certification by rheumatologist OR ICD9-CM code 714 in HDF OR leflunomide OR tocilizumab OR abatacept OR gold salts | 82.39 (77.61 to 86.52) | 96.20 (94.19 to 97.66) |
| Step 2: Step 1 OR (methotrexate AND antimalarials AND no certification for other autoimmune diseases) | 85.38 (80.88 to 89.17) | 95.63 (93.51 to 97.21) |
| Step 3: Step 2 OR (glucocorticoids ≥3 prescriptions AND antimalarials AND no certification for other autoimmune diseases) | 91.36 (87.60 to 94.28) | 92.21 (89.57 to 94.35) |
| Step 4: Step 3 OR (methotrexate ≥3 prescriptions AND no certification for other autoimmune diseases)* | 96.35 (93.56 to 98.16) | 90.30 (87.45 to 92.70) |
*The final algorithm used in the analysis.
ICD9-CM, International Classification of Diseases, Ninth Revision, Clinical Modification; HDF, hospital discharge form; RA, rheumatoid arthritis.