Table 3.

Relative Associations of eFI and Area Deprivation Categories with Acute Healthcare Utilization Including Additive and Multiplicative Effects

	eFI contrast HR (95% CI); P
Area deprivation	Pre-frail: Fit	Frail: Fit
Low	1.54 (1.45–1.65); < 0.001	2.39 (2.232.56); < 0.001
Mid (mid 35%)	1.43 (1.32–1.55); < 0.001	2.44 (2.25–2.65); < 0.001
High (top 15%)	1.58 (1.41–1.78); < 0.001	2.64 (2.35–2.97); < 0.001
	Deprivation contrast HR (95% CI); P
eFI category	Mid: Low	High: Low
Fit	1.16 (1.06–1.28); 0.001	1.22 (1.08–1.38); 0.002
Pre-frail	1.08 (1.03–1.13); 0.001	1.25 (1.19–1.32); < 0.001
Frail	1.19 (1.13–1.25); < 0.001	1.35 (1.28–1.43); < 0.001
	Measure of interaction
eFI and ADI category	Additive effects (95% CI); P	Multiplicative effects (95% CI); P
Pre-frail and Mid	− 0.05 (− 0.17–0.08); 0.763	0.92 (0.83–1.02); 0.135
Pre-frail and High	0.17 (< 0.01–0.34); 0.028	1.02 (0.90–1.17); 0.720
Frail and Mid	0.29 (0.13–0.45); < 0.001	1.02 (0.92–1.13); 0.675
Frail and High	0.62 (0.41–0.83); < 0.001	1.11 (0.97–1.27); 0.142

Adjusted for age, race, gender, outpatient, and acute care utilization in the prior year, the interaction between eFI and ADI, and random effects for within-subject correlation. eFI indicates electronic frailty index, ADI indicates area deprivation index, HR indicates hazard ratio, and CI indicates confidence interval