. 2018 Apr 1;21(4):489–502. doi: 10.1089/jpm.2017.0566

Table 2.

Utilization and Costs Using a Difference in Difference Method

	ACP (N = 325)		Match (N = 325)		Unadjusted^a		Adjusted^b
	Pre-12 months before ACP date A	Last 12 months before death B	Pre-12 months before match date C	Last 12 months before death D	Difference-in-difference (B-D)-(A-C)	P	Difference-in-difference (B-D)-(A-C)	P
Total expenditure^c	$12,252	$31,961	$9936	$38,544	−$8898	0.008	−$9500	0.006
95% CI					−15449, −2347		−16207, −2793
Utilization
Inpatient admissions	0.47	1.42	0.28	1.55	−0.32	0.032	−0.37	0.011
95% CI					−0.61, −0.03		−0.66, −0.08
Inpatient days	3.07	9.29	1.90	11.47	−3.35	0.012	−3.66	0.005
95% CI					−5.97, −0.73		−6.23, −1.09
ICU days (inpatient)	0.06	1.87	0.01	1.98	−0.16	0.693	−0.24	0.570
95% CI					−0.95, 0.63		−1.06, 0.58
Hospice use	0.04	1.20	0.12	1.25	0.03	0.890	0.04	0.828
95% CI					−0.37, 0.42		−0.35, 0.44
Hospice days	0.90	23.85	3.33	26.81	−0.53	0.925	−0.23	0.968
95% CI					11.52,10.47		−11.15, 10.70
SNF use	0.18	0.80	0.27	1.01	−0.12	0.386	−0.14	0.296
95% CI					−0.38, 0.15		−0.41, 0.12
HHA use	0.32	0.60	0.21	0.56	−0.06	0.534	−0.09	0.379
95% CI					−0.25, 0.13		−0.27, 0.10
30-day readmissions	0.11	0.23	0.03	0.23	−0.08	0.150	−0.09	0.099
95% CI					−0.19, 0.03		−0.19, 0.02
ED visits	0.10	1.62	0.09	1.55	0.06	0.707	−0.01	0.972
95% CI					−0.26, 0.39		−0.32, 0.31

^{^a}

Generalized linear model with gamma distribution (expenditure) or Poisson distribution (utilizations).

^{^b}

Generalized linear model with gamma distribution (expenditure) or Poisson distribution (utilizations) adjusted by age, gender, race, CMS risk score, and comorbidities (CHF, COPD, ESRD, and cancer).

^{^c}

All expenditures were converted to 2016 U.S. dollar using Medical Component of Consumer Price Index. Note: For patients (N = 190 and each group N = 95) who do not have a full 12-month period between ACP date and death date, we used a multiple imputation method. Ten imputed values were obtained for each missing observation with the mean used for the missing value.

CI, confidence interval; SNF, skilled nursing facility; HHA, home health agency; ED, emergency department; LOS, length of stay.