Categories, ultrasound findings and statistics
| GCA risk category (n) | Vascular US | Final diagnosis | Sensitivity (%) (95% CI) | Specificity (%) (95% CI) | PPV(%) (95% CI) | NPV (%) (95% CI) | Prevalence (%) (95% CI) | Accuracy (%) (95% CI) | LR+ (95% CI) | LR− (95% CI) | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| GCA (n) | Non-GCA (n) | ||||||||||
| High (66) | Positive | 50 | 2 | 50/53 (94) (8499) | 11/13 (85) (5598) | 50/52 (96) (8799) | 11/14 (79) (5492) | 53/66 (80) (6989) | (50+11)/66 (92) (8397) | 6.13 (1.71,21.98) | 0.07 (0.02,0.21) |
| Negative/ND | 3 (3/0) | 11 (7/4) | |||||||||
| Intermediate (137) | Positive | 36 | 3 | 36/36 (100) (90 100) | 98/101 (97) (9299) | 36/39 (92) (8097) | 98/98 (100) (-) | 36/137 (26) (1934) | (36+98)/137 (98) (94 100) | 33.67 (11.04,102.64) | 0.00 |
| Negative/ND | 0 (0/0) | 98 (68/30) | |||||||||
| Low (151) | Positive | 0 | 3 | 0/0 (undefined) (−) | 148/151(98) (94 100) | 0/3 (0) (−) | 148/148 (100) (−) | 0/151(0) (0.00,2.41) | (0+148)/151 (98) (−) | – | – |
| Negative/ND | 0 (0/0) | 148 (78/70) | |||||||||
| Total (354) | Positive | 86 | 8 | 86/89 (97) (9099) | 257/265 (97) (9499) | 86/94 (91) (8496) | 257/260 (99) (97 100) | 89/354 (25) (2130) | (86+257)/354 (97) (9598) | 32.01 (16.16,63.40) | 0.03 (0.01,0.11) |
| Negative/ND | 3 (3/0) | 257 (153/104) | |||||||||
GCA, giant cell arteritis; LR+, positive likelihood ratio; LR−, negative likelihood ratio; ND, not done; NPV, negative predictive value; PPV, positive predictive value; US, ultrasound.