Managed care and medical expenditures of medicare beneficiaries

"This paper investigates the impact of Medicare HMO penetration on the medical care expenditures incurred by Medicare fee-for-service enrollees. We find that increasing penetration leads to reduced health care spending on fee-for-service beneficiaries. In particular, a one percentage point increase in Medicare HMO penetration reduces such spending by .9 percent. We estimate similar models for various measures of health care utilization and find penetration-induced reductions, consistent with our spending estimates. Finally, we present evidence that suggests our estimated spending reductions are driven by beneficiaries who have at least one chronic condition"--National Bureau of Economic Research web site.