What type of reimbursement system pays providers after services based on acuity?

The correct answer is that a retrospective payment system pays providers after services based on acuity. In this reimbursement model, providers receive payment after the delivery of care, allowing for adjustment based on the complexity or severity of the patient's condition, often measured by acuity. This means that if a patient's condition is more complicated, greater reimbursement can be made to reflect the increased level of care required.

The retrospective system contrasts with prospective payment systems, which set costs before services are rendered, regardless of the actual level of care involved. Capitation involves paying a fixed amount per patient regardless of the services provided, which does not take acuity into account. Flat rate payment systems also provide a predetermined payment amount per service regardless of the specific circumstances or complexity of the case. Thus, the retrospective payment system aligns payment closely with the actual services delivered and the patient's acuity, making it the correct option.