Table 3.
Discriminative Ability and Psychometric Properties of the AD8 and IQCODE
| Classification by Clinical Diagnoses | ||||
|---|---|---|---|---|
| AD8 | IQCODE | |||
| Not impaired (AD8 <2) | Impaired (AD8 ≥2) | Not impaired (IQCODE<3.4) | Impaired (IQCODE ≥ 3.4) | |
| No impairment | 34 | 10 | 39 | 5 |
| MCI | 0 | 13 | 7 | 6 |
| Dementia | 1 | 128 | 27 | 102 |
| Psychometric Properties | ||||
|---|---|---|---|---|
| Dementia vs. No Dementia | MCI vs. No Dementia | |||
| AD8 | IQCODE | AD8 | IQCODE | |
| AUC | .953 (.915–.992) | .930 (.885–.975) | .899 (.821–.978) | .772 (.606–.938) |
| Sensitivity, % | 99.2 (95.7–99.8) | 79.1 (71.3–85.2) | 100 (77.2–100) | 46.1 (23.2–70.9) |
| Specificity, % | 77.3 (63.0–87.2) | 88.6 (76.0–95.1) | 77.3 (63.0–87.2) | 88.6 (76.0–95.1) |
| PPV, % | 92.8 (87.2–96.0) | 95.3 (89.5–97.9) | 56.5 (36.8–74.4) | 54.6 (28.0–78.7) |
| NPV, % | 97.1 (85.5–99.5) | 59.1 (47.1–70.1) | 100 (89.9–100) | 84.8–(71.8–92.4) |
| + LR | 4.4 (3.6–5.3) | 6.9 (4.7–10.4) | 4.4 (3.6–5.4) | 4.1 (1.9–8.8) |
| − LR | 0.01 (0.001–0.07) | 0.24 (0.21–0.26) | 0 (undefined) | 0.6 (0.4–0.8) |
Area under the curve (95% confidence interval)
Note: MCI = mild cognitive impairment; IQCODE= Informant Questionnaire on Cognitive Decline in the Elderly AUC = area under the curve (parametric analyses); PPV = positive predictive value; NPV=negative predictive value; LR=likelihood ratio.