1. Clinical professional (nurse or social worker) who works with the patient and all those involved with the patient in coordinating a plan of medical necessity and appropriateness of health care. He or she reviews cases after a predetermined amount of time and certifies ongoing care. 2. Registered or licensed vocational nurse assigned to a workers’ compensation case to supervise the administration of medical or ancillary services provided to the patient.

Distribution of patients into categories reflecting differences in severity of illness or resource consumption. These categories include age, medical diagnosis, severity of illness, or length of stay. A nursing home or hospital’s actual case mix influences cost and scope of the services provided by the facility to the patient, and case mix reimbursement systems adjust payment rates accordingly.

1. Average relative weight of all cases treated at a facility or by a certain physician that reveals the clinical severity of a defined group in relation to other groups in the classification system. Formula: Divide the sum of the weights of diagnosis-related groups (DRGs) for patient discharged during a specified period by the total number of patients discharged. A low CMI may indicate DRG assignments that do not adequately reflect the resources used to treat Medicare patients. 2. In prospective payment systems, this is the comparison of a hospital’s cost for its case mix to the national or regional average hospital cost for a similar case mix.

Mathematical method used to determine the case mix index by taking the sum of all diagnosis-related groups’ (DRGs’) relative weights and dividing it by the number of Medicare cases.

1. Numeric assigned by the insurance carrier (payer) to an insurance claim. When appealing a denied or rejected claim, it must appear on each page of the document that is submitted to the payer. 2. See group number.

1. In managed health care, an averaging after a flat rate is given to certain categories of procedures. 2. Package price for a specific procedure or diagnostic-related group (DRG). Also called bundled rate or flat fee-per-case .