What is a common feature of case management under health maintenance organizations?

The correct answer highlights a fundamental aspect of case management in health maintenance organizations (HMOs), which is the coordination of patient care to decrease treatment duplication. This process is crucial in HMOs as they aim to provide efficient and cost-effective care. By coordinating patient care, case managers ensure that all healthcare providers involved in a patient's treatment are on the same page, which minimizes unnecessary tests, overlapping services, and miscommunication. This aligns with the overarching goal of HMOs to maintain health while managing costs, making sure resources are used wisely and effectively.

In contrast, patients with any illness being assigned a case manager does not accurately reflect the targeted approach of case management in HMOs, where assignment may be based on specific needs rather than a blanket policy for all illnesses. The notion that every patient receives a different care plan regardless of illness contradicts the standardized frameworks often employed by HMOs, where care plans may be developed with specific conditions in mind to streamline treatment and manage costs effectively. Lastly, the idea that case managers only oversee hospital admissions is limited and doesn't encompass the broader role they play in managing ongoing patient care across various levels, including preventive care and post-discharge planning.