Table 3.
PPV and NPV for AD clinical trial and diagnostic study MMSE cutoff scores for normal cognition versus MCI and AD dementia in NACC
| MMSE score | Sensitivity | Specificity | PPV | NPV |
|---|---|---|---|---|
| Normal cognition (n = 10,741) versus MCI (n = 5883) | ||||
| 18 | 0.4 | 100.0 | 85.2 | 64.4 |
| 19 | 0.6 | 99.9 | 86.0 | 64.4 |
| 20 | 1.0 | 99.8 | 78.7 | 64.5 |
| 21 | 1.6 | 99.8 | 79.8 | 64.6 |
| 22 | 2.8 | 99.6 | 79.9 | 64.9 |
| 23 | 4.8 | 99.3 | 78.7 | 65.3 |
| 24 | 8.4 | 98.5 | 75.9 | 66.0 |
| 25 | 13.5 | 96.8 | 69.9 | 66.8 |
| Cutoff score = 26 | 21.7 | 93.4 | 64.6 | 68.2 |
| 27 | 33.5 | 85.9 | 56.9 | 69.9 |
| Normal cognition (n = 10,741) versus AD dementia (n = 6814) | ||||
| 18 | 29.1 | 100.0 | 99.8 | 66.5 |
| 19 | 33.2 | 99.9 | 99.8 | 67.8 |
| 20 | 38.8 | 99.8 | 99.4 | 69.7 |
| 21 | 45.0 | 99.8 | 99.3 | 71.9 |
| 22 | 52.0 | 99.6 | 98.9 | 74.5 |
| 23 | 59.3 | 99.3 | 98.3 | 77.4 |
| Cutoff score = 24 | 67.0 | 98.5 | 97.0 | 80.8 |
| 25 | 67.0 | 98.5 | 97.0 | 80.8 |
| MCI (n = 5883) versus AD dementia (n = 6814) | ||||
| 18 | 29.1 | 99.4 | 98.4 | 52.3 |
| 19 | 33.2 | 99.0 | 97.6 | 53.7 |
| 20 | 38.8 | 98.4 | 96.8 | 55.7 |
| 21 | 45.0 | 97.2 | 95.3 | 58.0 |
| 22 | 52.0 | 95.2 | 93.3 | 60.8 |
| 23 | 59.3 | 91.6 | 90.1 | 63.8 |
| Cutoff score = 24 | 59.3 | 91.6 | 90.1 | 63.8 |
| 25 | 74.7 | 78.3 | 81.5 | 70.7 |
Abbreviations: NACC National Alzheimer’s Coordinating Center, MMSE Mini Mental State Examination, MCI mild cognitive impairment, AD Alzheimer’s disease, PPV positive predictive value, NPV negative predictive value
PPV and NPV are based on the prevalence of MCI and AD dementia in this sample. We present values beginning at cutoffs commonly used for determining MCI (≤26) and AD dementia (≤24) in clinical trials and diagnostic studies. MMSE scores <18 continued to decline in NPV and increase in PPV and thus are not presented