Appendix Table 3.

Effect of MA Managed Care Penetration on MBSF Measures of Outpatient Utilization

	Part B Physician Office Visits	Home Health Visits	Hospice Stays	Hospital Outpatient Visits	Skilled Nursing Facility Stays
Penetration (Instrumented)	33.02b (14.17)	193.3 (117.8)	0.0145 (0.113)	6.529 (14.64)	0.374 (0.239)
R-squared	0.123	0.036	0.049	0.119	0.063
Mean of Dep Var	6,910	3,431	24	5,806	88
10 Pct Pt Pen Incr. Effect (%)	4.78	56.34	0.60	1.13	4.25

Notes: Number of observations: 60,940,793. MA Penetration is in percentages (ranging from 0 to 100). Results for utilization are per 1000 enrollees. Data are from CMS Medicare claims, Medicare beneficiary enrollment files, and MA ratebook files for 1999–2011. Estimated using Y_ict= α_c + β_t + β₁ MA Penetration_c(t−1) + β₂ [County Level Covariates] _ct + β₃ [Enrollee Level Covariates] _ict where Y_ict is a measure of utilization for individual i in area c in year t. MA Penetration_c(t−1) represents the percent of Medicare enrollees in an HMO or PPO MA plan as of January 1^st, and β_t and α_c represent year and county dummies, respectively. First stage enrollee-level results estimated using MA Penetration_c(t−1) = α_c + γ_t+ γ₁Payment_c(t−1) + γ₂[County Level Covariates] _ct + γ₃[Enrollee Level Covariates] _ict, where γ_t and α_c represent year and county dummies. Enrollee-level covariates include age, female dummy, and race dummies, as well as 70 HCC dummies. County-level covariates include percent male, percent white, percent black, percent Hispanic, population size, percent aged 65 to 69, percent aged 70 to 74, percent aged 75 to 79, percent aged 80 to 84, percent aged 85 plus, per capita income, poverty rate, unemployment rate, and the per capita number of GPs, specialists, surgeons, and other physicians that are office-based, full-time hospital staff, and hospital residents. Standard errors in parentheses (robust, clustered on county). Bottom row shows the effect implied by the coefficient of a 10 percentage point increase in penetration on the outcome as a percent of the mean value of the outcome. Results control for county fixed effects and HCCs.

^ap < 0.01,

^bp < 0.05,

^cp < 0.10