Student's t test was used to test for group differences in the mean cost per eligible enrollee per month for partial-capitation and full-capitation programs and to compare mean cost differences among PCMPs, HMOs, and PHSPs. The Discussion section below includes insights provided by two of the authors (T.C.R.

While not included in our analysis, it is relevant to note that the state commissioned quality assurance reviews by the Island Peer Review Organization for the HMOs and PHSPs in 1992 using the Health Employer Data Information Set (HEDIS), with modifiers added for well-child care, immunizations, and prenatal services.(13) Enrollee satisfaction was assessed by a questionnaire administered to 8456 enrollees.

This adds 3% to the cost of the PCMP programs but does not alter the comparison of savings between PCMP and control (t=3.38; P[less than].05), between PCMP and HMOs (t=2.56; P[less than].05), and between PCMPs and PHSPs (t=1.75; P[less than].10).

Partial capitation PCMPs Erie PCMP II 20,610 85.17 132.57 Erie PCMP III 14,827 97.40 178.34 Full capitation HMOs Metropolitan 46,520 227.91 237.04 HIP Corp 358,024 122.93 142.11 Mid Hudson-Ulster 16,966 88.72 69.15 Wellcare/Orange 16,262 99.14 81.00 Sanus/Suffolk 40,777 114.44 105.36 PHSPs Bronx PHSP 131,871 127.91 149.67 Health care plan plus 12,697 85.92 80.58 Westchester PHSP 24,101 100.94 119.58 Manhattan PHSP 43,619 167.14 221.11

Partial capitation PCMPs Erie PCMP II 47.40 Erie PCMP III 80.94 Full capitation HMOs Metropolitan 9.13 HIP Corp 19.18 Mid Hudson-Ulster 19.57(1) Wellcare/Orange 13.19(1) Sanus/Suffolk 9.08(1) PHSPs Bronx PHSP 21.76 Health care plan plus 5.36(1) Westchester PHSP 18.64 Manhattan PHSP 53.97

PCMP 35,437 94.04 151.79 HMOs 478,549 130.19 143.50 PHSPs 212,288 130.29 156.68 Total 726,274 128.45 147.74 All NYS 1992 capitated 1,111,618 116.88 126.70 Medicaid managed care plans

PCMP 57.75 38.0(1) HMOs 13.31 9.3(2) PHSPs 26.39 16.8(3) Total 19.29 13.1 All NYS 1992 capitated 11.82 9.3 Medicaid managed care plans

(3) Significance of PCMP savings vs PHSPs: t=1.75, P=NS.

Further confounders include change in the hospital used, change in physician group, and the different reporting formats required of HMOs, PHSPs, and PCMPs.

Data collected by the New York State Department of Social Services were used to compare the costs for matched cohorts enrolled in partial capitation programs in which the primary care physician is paid a monthly fee to provide ambulatory primary care for Medicaid recipients; and full capitation programs in which a health maintenance organization (HMO) or a hospital-based prepaid health services program (PHSP) is paid a more encompassing monthly fee to provide a larger range of services, including inpatient, outpatient, and specialty care.