Table 2.
Effect of Sex and APOE ε4 on longitudinal change in ADAS-Cog11 of MCI subjects.
| Term | Coefficient | Standard error | t-value | p-value |
|---|---|---|---|---|
| Intercept | 3.544899 | 0.06782345 | 52.26658 | <0.001 |
| Sex effect | 0.255545 | 0.08529762 | 2.99592 | 0.003 |
| APOE ε4 + effect | 0.308539 | 0.08876979 | 3.47572 | <0.001 |
| APOE ε4 + + effect | 0.568898 | 0.13237472 | 4.29763 | <0.001 |
| Baseline rate | 0.012660 | 0.00181201 | 6.98689 | <0.001 |
| Baseline curvature | 0.000099 | 0.00001834 | 5.39852 | <0.001 |
| Age effect | 0.011337 | 0.00560956 | 2.02101 | 0.044 |
| Education effect | 0.016933 | 0.01428969 | 1.18500 | 0.237 |
| Baseline cognition effect | 0.166261 | 0.00932751 | 17.82485 | <0.001 |
| Female effect on slope | 0.006905 | 0.00231191 | 2.98663 | 0.003 |
| Female effect on curvature | 0.000006 | 0.00002605 | 0.24503 | 0.807 |
| APOE ε4 + effect on slope | 0.010323 | 0.00238571 | 4.32693 | <0.001 |
| APOE ε4 + + effect on slope | 0.018991 | 0.00362755 | 5.23525 | <0.001 |
| APOE ε4 + effect on curvature | 0.000071 | 0.00002589 | 2.76107 | 0.006 |
| APOE ε4 + + effect on curvature | 0.000115 | 0.00004004 | 2.87349 | 0.004 |
| Education effect on slope | 0.000780 | 0.00038381 | 2.03293 | 0.042 |
| Age effect on slope | 0.000142 | 0.00015109 | 0.94080 | 0.347 |
| Baseline cognition effect on slope | 0.001074 | 0.00025382 | 4.23056 | <0.001 |
Baseline cognition indicates ADAS-Cog 11. Bold p-values are statistically significant. Abbreviations: MCI (mild cognitive impairment), ADAS-Cog11 (Alzheimer’s disease assessment scale- cognitive subscale), and APOE ε4 (apolipoprotein ε4 allele). In this model, the follow-up time (month) was centered with the median follow-up time (36 months) and covariates were centered i.e. a 75 years old APOE ε4- male with 16 years of education and an ADAS-Cog11 of 11. Table depicts that the effect of sex on ADAS-Cog11 change was significant with females declining faster than males. Education and baseline cognition also had significant effects. The intercept is a term to get the correct estimate of the outcome when time = 0. The baseline rate is the reference population rate of change in the outcome starting at time zero, and the baseline curvature is the “acceleration” of that rate of change at time zero. The upper half of the table shows the effect of specific variables on ADAS-Cog11 and the bottom half shows their effects on ADAS-Cog11 slope and curvature.