. 2011 Oct;46(5):1333–1361. doi: 10.1111/j.1475-6773.2011.01276.x

Table 3.

Instrumental Variables (IV) and Ordinary Least Squares (OLS) Estimates of Medical Spending (Cumulative Total) and Health Outcomes (Final HALex) Models

	IV				OLS

	First-Stage Spending Model		Second-Stage Health Outcome Model		Health Outcome Model

Variable (N = 17,438)	Coefficient	t	Coefficient	z	Coefficient	t
Medical spending (U.S.$1,000s)			0.0043^b	2.00	−0.0013^a	−18.00
EOLEI (exogenous identifying variable)	0.545^a	4.06
Prior health status
Self-reported general health status (reference = excellent)
Very good	3.427^a	6.01	−0.090^a	−9.42	−0.071^a	−14.53
Good	6.523^a	9.58	−0.180^a	−11.33	−0.143^a	−27.29
Fair	15.312^a	13.64	−0.350^a	−10.11	−0.263^a	−37.64
Poor	24.801^a	11.31	−0.450^a	−8.04	−0.309^a	−32.54
Any ADL	10.721^a	11.96	−0.208^a	−8.70	−0.148^a	−27.04
Any IADL	8.022	9.76	−0.196^a	−10.40	−0.151^a	−28.17
Change in HALex, baseline to year 1	−37.462^a	−20.87	0.668^a	8.14	0.456^a	40.91
Change in HALex, year 1–year 2	−24.753^a	−15.02	0.462^a	8.39	0.322^a	29.86
Conditions
Had hardening of the arteries at baseline	0.682	0.57	−0.007	−0.73	−0.002	−0.41
Developed hardening of the arteries, year 1	6.896^b	2.31	−0.025	−0.99	0.015	1.19
Developed hardening of the arteries, year 2	9.450^a	3.59	−0.059^b	−2.14	−0.005	−0.39
Had hypertension at baseline	1.000^c	1.72	−0.018^a	−3.20	−0.012^a	−3.13
Developed hypertension, year 1	2.512^c	1.71	−0.028^b	−2.14	−0.014	−1.55
Developed hypertension, year 2	4.759^a	2.99	−0.036^b	−2.20	−0.008	−0.92
Had heart attack at baseline	4.329^a	3.91	−0.027^b	−2.14	−0.003	−0.47
Developed heart attack, year 1	16.564^a	5.17	−0.094^b	−2.21	0.000	0.01
Developed heart attack, year 2	14.276^a	4.28	−0.056	−1.47	0.025^c	1.72
Had angina pectoris or other coronary heart disease at baseline	4.493^a	3.95	−0.023^c	−1.72	0.003	0.50
Developed angina or coronary heart disease, year 1	1.956	0.93	0.005	0.30	0.017	1.37
Developed angina or coronary heart disease, year 2	9.792^a	3.70	−0.039	−1.39	0.017	1.28
Had other heart conditions at baseline	4.071^a	5.44	−0.028^b	−2.55	−0.005	−1.11
Developed other heart condition, year 1	11.992^a	7.02	−0.070^b	−2.40	−0.002	−0.28
Developed other heart condition, year 2	5.319^a	3.57	−0.056^a	−3.32	−0.025^a	−3.01
Had stroke or brain hemorrhage at baseline	0.912	0.70	−0.021^b	−2.13	−0.016^b	−2.55
Developed stroke or brain hemorrhage, year 1	13.669^a	4.10	−0.081^b	−2.32	−0.005	−0.44
Developed stroke or brain hemorrhage, year 2	8.405^a	4.11	−0.071^a	−2.99	−0.024^b	−2.29
Had skin cancer at baseline	−0.098	−0.11	0.001	0.18	0.001	0.19
Developed skin cancer, year 1	−3.237^c	−1.94	0.015	0.95	−0.003	−0.28
Developed skin cancer, year 2	0.018	0.01	−0.014	−1.07	−0.014	−1.42
Had other cancer at baseline	3.537^a	4.29	−0.036^a	−3.51	−0.016^a	−3.26
Developed cancer, year 1	12.042^a	5.17	−0.073^b	−2.20	−0.005	−0.32
Developed cancer, year 2	20.494^a	8.69	−0.135^a	−2.78	−0.019	−1.27
Had diabetes at baseline	10.206^a	9.47	−0.087^a	−3.71	−0.029^a	−5.27
Developed diabetes, year 1	−0.473	−0.38	−0.024^b	−2.14	−0.027^a	−2.95
Developed diabetes, year 2	−1.437	−1.54	−0.030^a	−3.11	−0.038^a	−5.13
Additional health variables
Proxy respondent	5.807^a	3.45	−0.050^a	−2.95	−0.016^b	−2.17
Current smoker	1.849^b	2.00	−0.040^a	−4.40	−0.029^a	−4.84
Former smoker	2.063^a	3.55	−0.016^b	−2.33	−0.004	−1.05
LT 10th percentile of body mass index (reference = 25th–75th percentile)	1.151	0.99	−0.025^a	−2.65	−0.018^a	−2.86
10th–25th percentile of body mass index	−0.726	−1.02	−0.009	−1.32	−0.013^b	−2.52
GT 75th percentile of body mass index	−1.422^b	−2.00	0.003	0.48	−0.005	−1.07
Upper body limitation (some or lot of difficulty, or unable)	0.996	1.19	−0.025^a	−3.49	−0.019^a	−3.81
Lower body limitation (some or lot of difficulty, or unable)	1.780^b	2.45	−0.039^a	−5.23	−0.029^a	−6.16
Education (reference = LT high school)
High school graduate	2.415^a	3.35	−0.006	−0.79	0.007^c	1.68
Some college	2.890^a	3.27	−0.007	−0.68	0.009^c	1.62
College graduate	3.620^a	3.97	−0.012	−1.06	0.009	1.44
Family income (reference = LT U.S.$10,000)
U.S.$10,000–20,000	2.112^b	2.31	−0.007	−0.76	0.005	1.04
U.S.$20,000–30,000	1.966^b	2.07	−0.004	−0.47	0.007	1.20
U.S.$30,000–40,000	2.767^b	2.41	0.007	0.63	0.023^a	3.33
U.S.$40,000 or more	3.607^a	3.57	0.006	0.52	0.027^a	4.23
Age (reference = 65–67)
68–70	0.926	0.98	−0.024^a	−3.08	−0.019^a	−3.38
71–74	1.015	1.13	−0.040^a	−5.24	−0.034^a	−6.08
75–79	1.256	1.39	−0.063^a	−8.07	−0.056^a	−10.01
80–84	2.636^a	2.60	−0.107^a	−10.80	−0.091^a	−14.90
85 or older	4.736^a	3.48	−0.164^a	−11.32	−0.137^a	−18.26
Female (reference = male)	−2.245^a	−3.36	0.016^b	2.21	0.004	0.95
Race/ethnicity (reference = white non-Hispanic)
Asian	−7.487^a	−3.54	0.045	1.62	0.005	0.26
African American	−1.466	−1.23	0.000	0.04	−0.005	−0.79
White Hispanic	−1.847	−1.07	0.000	0.03	−0.006	−0.52
Other race	−4.818^b	−2.21	0.015	0.71	−0.010	−0.74
Year	0.311^a	3.21	0.001	0.53	0.002^a	3.66
Constant	−6.487^a	−3.23	0.929^a	81.88	0.927^a	110.65

Note. IV test statistics.

Partial R² of excluded instruments: 0.0009.

Kleibergen-Paap rk Wald F Statistic: 16.448.

Stock-Yogo weak ID test critical values.

10% maximal IV relative bias: 16.380.

p<.01

.01<p≤.05

.05<p≤.10.

ADL, activities of daily living; EOLEI, End-of-Life Expenditure Index; HALex, Health and Activity Limitation Index; IADL, instrumental activities of daily living.