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Overview of ACOs in Healthcare

Sep 7, 2025

Overview

This article explains how Accountable Care Organizations (ACOs), created under the Affordable Care Act, aim to make healthcare more efficient and cost-effective through coordinated provider networks, incentives for quality care, and shared savings models.

What Are Accountable Care Organizations?

  • ACOs are networks of doctors and hospitals sharing responsibility for coordinated patient care to reduce unnecessary spending.
  • Each ACO manages care for at least 5,000 Medicare beneficiaries over three years.
  • Primary care physicians are central to each patient's care within an ACO.

Purpose and Structure of ACOs in the ACA

  • The ACA introduced ACOs to help reduce Medicare costs and improve care efficiency.
  • The Medicare Shared Savings Program holds providers jointly accountable and incentivizes cooperation to avoid unnecessary tests and procedures.
  • The Pioneer Program enables high-performing systems to earn greater savings in exchange for more financial risk.

Payment and Incentives

  • Traditional fee-for-service remains, but ACOs can earn bonuses for keeping costs down and meeting quality benchmarks.
  • ACOs that fail to meet standards may incur penalties or lose invested costs for care improvement.
  • Physician- or rural-based ACOs may receive advance payments to build necessary infrastructure.

Patient Experience Within ACOs

  • Patients are generally referred to providers within the ACO but may see out-of-network doctors without penalty.
  • Providers must inform patients about ACO participation and allow them to opt out of data sharing.

Governance and Stakeholders in ACOs

  • ACOs must include primary care doctors but can also feature hospitals, specialists, insurers, and private companies.
  • Insurers help with data collection and care evaluation but do not direct clinical care.
  • Large hospital systems or insurers may lead ACO formation due to capital and data capabilities.

Comparison to HMOs

  • Unlike HMOs, ACO patients are not required to remain in-network and retain freedom of provider choice.
  • ACOs are subject to strict quality measures to prevent cost-saving at the expense of necessary care.

Potential Risks and Downsides

  • The rise of ACOs may speed up hospital and provider consolidation, reducing patient choice and increasing prices.
  • Consolidation is seen as a larger systemic trend, not solely caused by ACOs.

Future of ACOs in Health Care

  • ACOs may be a transitional model toward a fully value-based care system.
  • The ultimate goal is for providers to take full financial responsibility for patient populations under fixed payments, moving beyond traditional ACOs.