Table 2.

Risk Estimates Associated with Digit Symbol Substitution Test (DSST) Score and Gait Speed (m/s)

				Standardized Hazard Ratio (95% Confidence Interval)
Event	Events n	Events per 1,000 Person-Years	Predictor	Model 1:(DSST+Age, Sex, Race, Education)	Model 2: (Model 1+Gait Speed)	Model 3: (Model 2+Confounders†)	Model 4: (Model 3+Brain Magnetic Resonance Imaging Variables‡)
Mortality	704	31.8	DSST	0.77(0.68–0.87)**	0.79(0.69–0.89)**	0.78(0.69–0.89)*	0.79(0.69–0.90)*
			Gait speed		0.87 (0.78–0.98)**	0.89 (0.80–0.99)*	0.90(0.80–1.00)*
Incident disability	1,096	35.0	DSST	0.75 (0.68–0.82)***	0.77 (0.70–0.85)***	0.76 (0.68–0.84)***	0.76 (0.69–0.84)***
			Gait speed		0.88 (0.80–0.96)***	0.88 (0.80–0.96)*	0.88 (0.81–0.97)**

Higher score and speed indicate better performance. Follow-up time from 1992 to 2002.

^†Confounders: subclinical disease, congestive heart failure, hypertension, diabetes mellitus, myocardial infarction, physical activity, modified Mini-Mental State Examination score, and grip strength.

^‡Includes presence of at least one subclinical brain infarct, ventricular enlargement ≥Grade 4 and white matter hyperintensities ≥Grade 3.

^***P< .001

^**.005

^*.03.