Maximum Allowable Cost. This is the amount payors will reimburse a pharmacy for a particular item.


Management of Aggressive Behavior.

Mad Cow Disease

Formally known as Bovine Spongiform Encephalopathy (see BSE).

Major Diagnostic Categories

Medicare cases are assigned to one of 492 DRGs in 25 major diagnostic categoriesExternal Page Policy 
(click to see policy and instructions) (MDCs). Most MDCs are based on a particular organ system of the body (e.g., MDC 6, “Diseases and Disorders of the Digestive System”); however, some MDCs are not constructed on this basis since they involve multiple organ systems (e.g., MDC 22, “Burns”).
In general, principal diagnosis determines MDC assignment. However, there are five DRGs to which cases are assigned on the basis of procedure codes instead. These are the DRGs for,
liver (DRG 480)
bone marrow (DRG 481)
lung transplant (DRG 495)
and the two DRGs for tracheostomies (DRGs 482 and 483). Cases are assigned to these DRGs before classification to an MDC.
Within most MDCs, cases are then divided into,
Surgical DRGs — based on a surgical hierarchy that orders individual procedures or groups of procedures by resource intensity, and
Medical DRGs — generally are differentiated on the basis of diagnosis and age.
Some surgical and medical DRGs are further differentiated based on the presence or absence of complications or co-morbidities.


Any commodity used directly or indirectly in performing a surgery (producing a product).

Materials Management

The management functions related to the complete cycle of material flow, from ordering to receiving to usage and reporting.

Materials Requirement Planning (MRP)

A system which replans inventory requirements as a result of changes in the surgery schedule and inventory status.

Maximum Stock Level

The maximum allowable inventory level for given item.


Managed Care Organization, including HMOs, PPOs, and other Point-Of-Care providers.


Doctor of Medicine.

MD Link

A fictitious computer network for physicians, remarkably similar to the one planned by Physicians Desktop, Inc., the brainchild of Glen Lang, former President of Imonics. This is an excerpt from “The TakeoverExternal Page Policy 
(click to see policy and instructions),” by Stephen W. Frey,
The concept had been pretty simple: connect physicians’ offices directly with insurance companies via a computer system so that medical patient could be processed immediately -- before the patient left the office. Doctors would receive their payments in days versus months and cut down significantly on paperwork. Insurance companies would slash multiple layers of overhead and therefore save lots of salary costs. MD Link would produce the computer software for the system, sell it to the insurance companies and the doctors, and make a good bit of money not only selling the software, but also servicing and upgrading it down the road.


Major Diagnostic Categories.


Microbial Diseases LaboratoryExternal Page Policy 
(click to see policy and instructions). A division of California’s Department of Health ServicesExternal Page Policy 
(click to see policy and instructions).


An external data source, provided on CD-ROM. It provides benchmark data of specific NDC codes (i.e., specific pharmaceuticals).


Medicare Payment Advisory Commission.


A government insurance program for people who cannot pay for healthcare. Medicaid is administered by the states (e.g., California’s Medical) and financed by the states and the federal government (through the Social Security Administration).

Medical Information Bureau

The Medical Information Bureau in Massachusetts compiles information relating to the medical history and lifestyle of people who have conditions or participate in activities (such as sky diving) that may affect longevity. The non-profit bureau is financed and run by the insurance industry. It's mission is to help life and health insurance companies detect fraudulent applications.
Not everyone is on file at MIB. The company says it keeps reports only if a person has a serious medical condition or other factors that might affect longevity, such as a bad driving record or participation in a hazardous sport. The information is coded and stored by computer. MIB says it purges records that are more than 7 years old.
If the insurance company discovers, either from your application or from your medical files, that you have a condition significant to health or longevity, MIB requires them to report it. The agency can then keep it on file to share with other insurance companies who request information about you.
MIB's rules forbid an insurer from denying insurance based solely on an MIB report. The insurer is supposed to independently verify the information in the MIB report, but there is no means of assuring that this is done.
Since 1995, MIB has been regulated by the federal Fair Credit Reporting Act and requires its member insurance companies to abide by that law. That means if an MIB report plays any part in an insurer's decision to deny coverage or to charge a higher rate for insurance, the insurance company must notify you of this fact, and provide MIB's name and address. You can then request a free copy of that MIB report within 30 days of being notified by the insurance company.
If you disagree with the information, you can dispute it. When MIB receives notice of your dispute, Maryland law requires that it reinvestigate the information in question and record the current status within 30 days. However, the re-investigation does not ensure that faulty information will be removed from your file.
If the reinvestigation does not resolve your dispute, the Fair Credit Reporting Act and Maryland law permit you to file a brief statement with MIB, which must be included in your report each time it is sent out.
Even if you have not been denied insurance, you can get a copy of information MIB has on file about you by writing MIB at,
Medical Information Bureau
PO.Box 105
Essex Station
Boston, MA 02112
or by calling 617-426-3660. MIB will send the necessary forms. Under Maryland law, Maryland residents are entitled to one free copy of their MIB report within a 12-month period. Subsequent reports can cost no more than $8 (circa 1998).
If you are planning to apply for insurance, you should check first to see if you have an MIB report so you won't receive any surprises later on. If you have any trouble obtaining a free copy of your report, you can contact the Maryland Commissioner of Consumer Credit at (410) 333-6330.

Medical Savings Accounts

See MSA.


HCFA administers MedicareExternal Page Policy 
(click to see policy and instructions), the nation's largest health insurance program, which covers 37 million Americans. Medicare provides health insurance to people age 65 and over and those who have permanent kidney failure and certain people with disabilities.

Medicare Managed Care Plans

According to a July 17, 1998 MedscapeExternal Page Policy 
(click to see policy and instructions)articleExternal Page Policy 
(click to see policy and instructions), there are three basic types of Medicare managed care plans: risk plans, cost plans, and prepayment plans

Medicare Cost Plans

According to a published article, cost plans “are not at risk for the care provided to members enrolled in their plan. The plan is paid a predetermined amount per member/per month [cf., PMPM] based on a total estimated budget. However, any variances between the monthly payments and the budget are reconciled at the end of the year. Beneficiaries enrolled in a cost plan can receive Medicare-covered services outside of the plan without restriction.”

Medicare Prepayment Plans

According to a published article, prepayment plans “are similar to cost plans but do not cover Medicare Part A services (i.e., inpatient hospital care, skilled nursing, hospice, and some home health care).”

Medicare Risk Plans

According to the a published article, HCFA “pays Medicare risk HMOs a prospective per member/per month [cf., PMPM)] premium set at approximately 95% of the projected average expenses for fee-for-service beneficiaries in a given county. The risk HMO then assumes full financial risk for all Medicare-covered services to Medicare beneficiaries enrolling in the plan. With the exception of an emergency, members of a risk HMO are required to receive all care through the HMO and its contracted providers.”
“Medicare risk HMOs dominate the market, representing 307 of the 417 licensed Medicare managed care plans. Approximately 88% of the Medicare beneficiaries enrolled in a managed care plan are enrolled in a Medicare risk HMO.”

Medigap Insurance

These policies are designed to pay for some of the costs not covered by fee-for-service Medicare, such as deductibles and co-insurance.
Popularized by “Ed McMahon” (formerly Johnny Carson's sidekick, the pre-Jay Leno host of the Tonight Show).


Medi-SpanExternal Page Policy 
(click to see policy and instructions) is a third-party provider of data and categorizations of pharmaceuticals. In particular, NDC cross-reference data.


A Decision Support System (DSS) developed by Multum which assists physicians in prescribing and dosing pharmaceuticals to minimize adverse drug reactions. Using patient data from a hospital information systems, and a formulary the system will determine the correct dosage to prescribe. MediSource delivers patient-specific expert drug dosing and detailed therapy recommendations at the point of care while providing alerting about complications where appropriate. This system is currently used both for inpatient and outpatient.


Stands for MEDLARS On-line; in turn, MEDLARS stands for Medical Literature Analysis and Retrieval System. MEDLINEExternal Page Policy 
(click to see policy and instructions) is the National Library of Medicine’s (NLM) premier bibliographic database covering the fields of medicine, nursing, dentistry, veterinary medicine, the healthcare system, and the preclinical sciences.
The MEDLINE database may be accessed free of charge via Internet Grateful Med and PubMedExternal Page Policy 
(click to see policy and instructions).


Medicare Payment Advisory Commission, a congressional Medicare advisory panel.


The records for all Medicare hospital inpatient discharges are maintained in the Medicare Provider Analysis and Review (MedPAR) file. The data in this file are used to evaluate possible DRG classification changes and to recalibrate the DRG weights.


Medical and Surgical non-durable supplies (i.e., as opposed to pharmaceuticals).


See Medical Information Bureau.


MicromedexExternal Page Policy 
(click to see policy and instructions) is a third-party provider of data and categorizations of pharmaceuticals. In particular, NDC cross-reference data.


Medical Marketing AssociationExternal Page Policy 
(click to see policy and instructions). This proves that there is an association, and, thus, an abbreviation for everything.


Materials Management Information System.


Risk of death after treatment. It is usually measured on a 1-to-4 scale, with 1 being the least complex,
Code Description
1 Minor
2 Moderate
3 Major
4 Extreme


Magnetic Resonance Imaging.


Medical Savings Accounts. These were established under HIPAA as a demonstration project to encourage personal savings for healthcare expenses. MSAs allow individuals and small group employers (50 and fewer employees) to open tax advantaged savings accounts in order to pay routine medical expenses and accrue savings for future medical expenses. Participants are required to maintain a qualifying high-deductible health plan to cover large expenses. MSA contributions are fully tax-deductible and balances carry over year to year; the interest earned is not taxed. Fund withdrawals to pay for qualifying medical expenses are not taxed, but withdrawals for non-medical purposes (before age 65) are taxed and assessed a 15 percent penalty.


Management Services Organization. A joint venture between a hospital and doctors where the MSO owns the practice hard assets but physicians still control the revenue. The MSO provides services to its member physicians (e.g., practice management, consulting).


Medical Treatment Facility.


Magnetic Resonance Imaging. Originally, it was called “NMR.”


Short hand for “metastasis.” According to the the Webster Medical DictionaryExternal Page Policy 
(click to see policy and instructions),
Pronunciation: m&-'tas-t&-s&s
Function: noun
Inflected Form(s): plural /-"sEz/
: change of position, state, or form: as a: transfer of a disease-producing agency (as cancer cells or bacteria) from an original site of disease to another part of the body with development of a similar lesion in the new location <me-tas-ta-sis in the lung usually occurs by way of the blood stream -- J. B. Amberson> <metastases of breast cancer to bone -- Medical Physics> b: a secondary metastatic growth of a malignant tumor
Roughly, this translates to: “bad news, the disease (e.g., cancer) has spread.”
See also, Dx, Fx, Hx, Px, Rx, Sx, Tx.