Autism diagnosis results: phase 1 and phase 2
| Autism | TP | FN | FP | TN | Sensitivity | Specificity | PPV | NPV | AUC |
| Main analysis: phase 1 | |||||||||
| Q-CHAT 39+ | 36 | 0 | 179 | 3428 | 1.00 (0.72 to 1.0)* | 0.95 (0.92 to 0.97) | 0.17 (0.08 to 0.31) | 1.00 (0.93 to 1.0)* | 0.98 (0.96 to 1.00) |
| Main analysis: phase 2 | |||||||||
| Q-CHAT 39+ | 27 | 34 | 69 | 3513 | 0.44 (0.26 to 0.64) | 0.98 (0.97 to 0.99) | 0.28 (0.15 to 0.46) | 0.99 (0.98 to 0.99) | 0.86 (0.78 to 0.94) |
| CAST ≥15+/CFR positive | 50 | 7 | 98 | 3488 | 0.88 (0.63 to 0.97) | 0.97 (0.95 to 0.98) | 0.34 (0.23 to 0.46) | 1.00 (0.99 to 1.00) | 0.99 (0.98 to 1.00) |
| Sensitivity analysis: phase 1 | |||||||||
| Q-CHAT 31+ | 36 | 0 | 1104 | 2504 | 1.00 (0.72 to 1.0)* | 0.69 (0.53 to 0.82) | 0.03 (0.01 to 0.07) | 1.00 (0.88 to 1.0)* | 0.98 (0.96 to 1.00) |
| Q-CHAT 38+ | 36 | 0 | 238 | 3369 | 1.00 (0.71 to 1.0)* | 0.93 (0.90 to 0.96) | 0.13 (0.06 to 0.25) | 1.00 (0.92 to 1.0)* | 0.98 (0.96 to 1.00) |
| Q-CHAT 39+ with parental concern | 30 | 6 | 73 | 3534 | 0.84 (0.43 to 0.97) | 0.98 (0.97 to 0.99) | 0.29 (0.13 to 0.52) | 1.00 (0.99 to 1.00) | 1.00 (0.99 to 1.00) |
| Q-CHAT 39+ adjust initial non-response | 49 | 0 | 201 | 3393 | 1.00 (0.72 to 1.0)* | 0.94 (0.91 to 0.97) | 0.20 (0.09 to 0.37) | 1.00 (0.93 to 1.0)* | 0.98 (0.96 to 1.00) |
| Sensitivity analysis: phase 2 | |||||||||
| Q-CHAT 31+ | 48 | 13 | 589 | 2993 | 0.79 (0.64 to 0.89) | 0.84 (0.65 to 0.93) | 0.08 (0.03 to 0.19) | 1.00 (0.99 to 1.00) | 0.86 (0.78 to 0.94) |
| Q-CHAT 38+ | 35 | 26 | 92 | 3489 | 0.57 (0.39 to 0.74) | 0.97 (0.96 to 0.99) | 0.28 (0.16 to 0.43) | 0.99 (0.99 to 1.00) | 0.86 (0.78 to 0.94) |
| Q-CHAT 39+ with parental concern | 24 | 37 | 29 | 3553 | 0.40 (0.23 to 0.60) | 0.99 (0.98 to 1.00) | 0.46 (0.24 to 0.69) | 0.99 (0.98 to 0.99) | 0.90 (0.84 to 0.96) |
| Q-CHAT 39+ adjust initial non-response | 38 | 35 | 73 | 3497 | 0.51 (0.30 to 0.72) | 0.98 (0.96 to 0.99) | 0.34 (0.17 to 0.55) | 0.99 (0.98 to 0.99) | 0.89 (0.81 to 0.96) |
| CAST ≥15 | 32 | 25 | 8 | 3578 | 0.56 (0.37 to 0.74) | 1.00 (0.99 to 1.00) | 0.81 (0.59 to 0.92) | 0.99 (0.99 to 1.00) | 0.94 (0.88 to 0.99) |
| Q-CHAT 39+ includes parent-reported cases | 30 | 34 | 67 | 3512 | 0.47 (0.30 to 0.65) | 0.98 (0.97 to 0.99) | 0.31 (0.52 to 0.82) | 0.99 (0.98 to 0.99) | 0.86 (0.79 to 0.94) |
*One-sided CI due to perfect predictor (not weighted).
AUC, area under the receiver operating characteristic curve; CAST, Childhood Autism Spectrum Test; CFR, Checklist for Referral; FN, false negative cases; FP, false positive cases; NPV, negative predictive value; PPV, positive predictive value; Q-CHAT, Quantitative Checklist for Autism in Toddlers; TN, true negative cases; TP, true positive cases.