Descriptive statistics for RA case definition criteria (n=148)
| Case definition criteria | Frequency (%) | Sensitivity Mean (SD) | Specificity Mean (SD) | Youden’s index Mean (SD) |
| Cohort | ||||
| 20+ years | 57 (38.5) | 90.9 (17.1) | 82.2 (7.5) | 73.1 (15.3) |
| 65+ years | 91 (61.5) | 91.3 (15.2) | 86.1 (7.4) | 77.4 (13.9) |
| Hospital diagnoses | ||||
| 0 | 52 (35.1) | 96.7 (2.4) | 83.7 (6.8) | 80.4 (5.9) |
| 1+ | 96 (64.9) | 88.1 (19.0) | 85.1 (8.0) | 73.2 (17.0) |
| ER diagnoses | ||||
| 0 | 138 (93.2) | 92.6 (12.8) | 84.8 (6.8) | 77.4 (12.4) |
| 1+ | 10 (6.8) | 71.4 (34.1) | 81.3 (14.9) | 52.7 (22.1) |
| Physician diagnoses | ||||
| 0 | 8 (5.4) | 30.7 (4.4) | 96.9 (1.1) | 27.7 (5.0) |
| 1+ | 16 (10.8) | 98.4 (2.4) | 71.3 (9.7) | 69.7 (8.7) |
| 2+ | 64 (43.2) | 93.5 (9.2) | 83.2 (4.8) | 76.7 (10.6) |
| 3+ | 60 (40.5) | 94.7 (2.1) | 88.0 (3.7) | 82.8 (3.0) |
| Specialist diagnoses | ||||
| 0 | 72 (48.7) | 85.8 (21.4) | 81.8 (9.5) | 67.5 (17.2) |
| 1+ | 76 (51.4) | 96.2 (2.7) | 87.3 (3.8) | 83.5 (2.8) |
| Physician diagnosis observation time | ||||
| Never | 8 (5.4) | 30.7 (4.4) | 96.9 (1.1) | 27.7 (5.0) |
| ≤1 year | 38 (25.7) | 94.9 (2.8) | 87.5 (5.4) | 82.4 (3.9) |
| ≤2 years | 40 (27.0) | 94.6 (7.3) | 85.0 (4.4) | 79.6 (8.5) |
| ≤5 years | 44 (29.7) | 93.2 (8.7) | 84.1 (4.5) | 77.3 (10.6) |
| Unlimited | 18 (12.2) | 97.6 (2.9) | 73.1 (10.6) | 70.7 (8.8) |
| ≥60 days between physician diagnoses | ||||
| Yes | 14 (9.5) | 79.8 (11.1) | 80.5 (2.9) | 60.3 (10.8) |
| No | 134 (90.5) | 92.3 (15.8) | 85.0 (7.8) | 77.3 (13.9) |
| Exclusion criteria A | ||||
| Yes | 10 (6.8) | 73.2 (2.6) | 80.8 (1.3) | 54.0 (2.6) |
| No | 138 (93.2) | 92.4 (15.6) | 84.9 (7.8) | 77.3 (13.7) |
| Exclusion criteria B | ||||
| Yes | 8 (5.4) | 73.7 (2.6) | 80.5 (1.2) | 54.2 (2.8) |
| No | 140 (94.6) | 92.1 (15.7) | 84.8 (7.8) | 77.0 (14.0) |
| RA-related medications, including steroids | ||||
| 0 | 74 (50.0) | 91.3 (15.2) | 86.5 (7.1) | 77.8 (14.0) |
| 1+ | 17 (11.5) | 91.1 (15.5) | 84.5 (8.4) | 75.8 (13.5) |
| Missing | 57 (38.5) | 90.9 (17.1) | 82.2 (7.5) | 73.1 (15.3) |
| RA-related medications, excluding steroids | ||||
| 0 | 74 (50.0) | 91.9 (15.3) | 84.9 (7.5) | 76.8 (14.0) |
| 1+ | 17 (11.5) | 88.7 (14.8) | 91.2 (3.7) | 79.9 (13.5) |
| Missing | 57 (38.5) | 90.9 (17.1) | 82.2 (7.5) | 73.1 (15.3) |
Exclusion criteria A excluded individuals with 2+ physician diagnosis codes with a different rheumatology diagnosis than an RA diagnosis; exclusion criteria B excluded individuals whose RA diagnosis was not confirmed by a specialist. Note: the attributes for age group, diagnoses in physician records and length of physician diagnosis observation time are not mutually exclusive.
ER, emergency room; RA, rheumatoid arthritis.