Table 4.
Variables contributing to the hazard ratio and time to decline after controlling for baseline group membership (NCI vs SCI), demographic variables,* and follow-up time
| Hazard ratio for additional variable† | P value† | Percent change in decline time‡ | P value‡ | |
|---|---|---|---|---|
| MMSE | 0.9 (0.7 to 1.0) | .058 | 5.1 (−0.1 to 10.5) | .054 |
| BCRS total score | 1.2 (1.0 to 1.3) | .011§ | −5.8 (−10.4 to −2.0) | .006¶ |
| BCRS axis 1: concentration and calculation | 15 (1.1 to 2.0) | .004¶ | −13.1 (−21.3 to −4.9) | .004¶ |
| BCRS axis 2: recent memory | 1.2 (0.8 to 1.9) | .453 | −7.7 (−22.1 to 8.3) | .335 |
| BCRS axis 3: remote memory | 1.1 (0.8 to 1.5) | .611 | −3.0 (−13.9 to 9.4) | .603 |
| BCRS axis 4: orientation | 1.3 (0.8 to 2.2) | .258 | −11.3 (−25.9 to 6.2) | .181 |
| BCRS axis 5: daily functioning | 1.5 (1.0 to 2.4) | .065 | −17.3 (−29.5 to −2.0) | .030§ |
| HAM-D total score** | 1.0 (1.0 to 1.1) | .263 | −1.0 (−3.0 to 1.0) | .266 |
| HAM-D item 8: slowness, decreased concentration | 1.4 (1.0 to 2.0) | .047§ | −12.2 (−22.1 to −9.5) | .031§ |
| HAM-D item 11: anxiety symptoms | 1.6 (1.2 to 2.2) | .004¶ | −14.8 (−23.7 to −3.9) | .007¶ |
| BEHAVE-AD total score††> | 1.0 (0.9 to 1.2) | .747 | −1.0 (−5.8 to 4.1) | .666 |
| BEHAVE-AD item 23: miscellaneous anxieties | 1.3 (0.8 to 2.0) | .230 | −10.4 (−22.9 to 5.1) | .178 |
| PDS‡‡ | 1.7(1.3 to 2.1) | .000§§ | −17.3 (−23.7 to −10.4) | .000§§ |
| Paragraphs delayed recall | 0.9 (0.9 to 1.0) | .028§ | 3.0 (0.2 to 5.1) | .035§ |
| Paired associates initial recall | 0.9 (0.8 to 1.0) | .006¶ | 5.1 (1.0 to 8.3) | .005¶ |
| Paired associates delayed recall | 0.9 (0.9 to 1.0) | .005¶ | 5.1 (1.0 to 8.3) | .004¶ |
| Memory for designs | 0.8 (0.8 to 0.9) | .001¶ | 6.2 (3.0 to 10.5) | .001¶ |
| Digit span reverse | 0.8 (0.7 to 1.0) | .031§ | 7.3 (2.0 to 12.7) | .012§ |
| Digit symbol substitution test | 0.99 (0.97 to 1.00) | .080 | 0.6 (0.0 to 1.1) | .047§ |
| WAIS vocabulary | 0.97 (0.96 to 0.99) | .0003§§ | 0.9 (0.4 to 1.3) | .001¶ |
NOTE. See Table 2 for variable mean scores and standard deviations.
Abbreviations: NCI, no cognitive impairment; SCI, subjective cognitive impairment; MMSE, Mini-Mental State Examination; BRCS; Brief Cognitive Rating Scale; HAM-D, Hamilton Depression Scale; BEHAVE-AD, Behavioral Pathology in Alzheimer’s Disease rating scale; PDS, Psychometric Deterioration Score; WAIS, Wechsler Adult Intelligence Scale.
Age, gender, and educational level.
Estimated hazard ratios for decline and the corresponding 95% confidence intervals and P values for each variable are obtained through survival analyses controlling for baseline group, demographic variables, and follow-up time.
Percent change in and the corresponding 95% confidence interval for the expected survival time for each unit increase in the variable. Thus for the MMSE (marginally significant), each additional point is associated with a 5.1% increase in expected time to decline. For BCRS total scores, for example, each additional point is associated with a 5.8% decrease in expected time to decline.
P < .05.
P < .01.
Two constituent HAM-D item scores are significant, items 8 and 11. For definitions of these items, see the footnote in Table 2. Other constituent HAM-D items are not shown.
One individual item score on behavioral pathology in BEHAVE-AD is significant, item 23 (see Table 2 footnote for definition). Other constituent BEHAVE-AD items are not shown.
Individual tests from the PDS that are not shown (paragraphs initial recall and digit span forward) are not found to be significant. Note that the PDS and its individual tests are of the opposite signs, and thus their contributions to the percent change in decline time are in the opposite directions as well.
P < .001.