Table 2.
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.