Table 4.
Proposed plasma Aβ42/40 ranges for clinical decision makinga.
| Plasma Aβ42/40 range | Designation | ADRC, N (% of cohort) | PET positivity, N (%) | MCI, N (%) | AD, N (%) | ApoE4, N (%) | Real world, N (% of cohort) | Real world, projections of PET positivity, Nb | Potential next evaluation and management considerations |
|---|---|---|---|---|---|---|---|---|---|
| <0.150 | Positive (low ratio) | 91 (36.4) | 61 (67.0) | 50 (54.9) | 34 (37.4) | 43 (47.3) | 1,468 (23.7) | 984 | Follow up for AD workup (high risk) |
| 0.150–0.159 | Indeterminant (lower ratio) | 37 (14.8) | 31 (83.8)c | 14 (37.8) | 18 (48.7) | 25 (67.6) | 1,128 (18.2) | 945 | Follow up for AD workup (indeterminant risk) |
| 0.160–0.169 | Indeterminant (higher ratio) | 38 (15.2) | 7 (18.4) | 19 (50.0) | 2 (5.3) | 7 (18.4) | 1,080 (17.4) | 199 | Follow up for AD workup (low risk) |
| ≥0.170 | Negative (high ratio) | 84 (33.6) | 2 (2.4) | 41 (48.8) | 0 (0.0) | 13 (15.5) | 2,516 (40.6) | 60 | Follow up for non-AD etiology |
| All | All | 250 | 101 (40.4) | 124 (49.6) | 54 (21.6) | 88 (35.2) | 6,192 | 2,188 |
Aβ, beta-amyloid; AD, Alzheimer’s disease; ApoE4, apolipoprotein E4 proteoform; MCI, mild cognitive impairment. aPercentage of individuals falling within a range unless otherwise specified. bReal world projections of positron emission tomography (PET) positivity are based on percent PET positivity in the Alzheimer’s Disease Research Center (ADRC) cohort. cNo statistically significant difference was observed between the percentage of PET positivity in the <0.150 and 0.150–0.159 groups (p = 0.090 by 2-sample test for equality of proportions with continuity correction).