the basis for inpatient payment under the Medicare prospective payment system (PPS).


Effectiveness describes the extent to which a specific intervention, when used under ordinary circumstances, does what it is intended to do. Effectiveness, therefore, takes into account the fact that, in any group of individuals, some will not take the intervention as prescribed, or will take other actions that may compromise the effect of the intervention (e.g., take drugs that might interact with the test intervention).


Efficacy is defined as the extent to which an intervention produces a beneficial result under ideal conditions.

end-stage renal disease (ESRD)

Irreversible kidney failure. To survive, the patient must either receive a kidney transplant or periodic kidney dialysis. Individuals with ESRD are eligible for Medicare benefits.

fiscal intermediaries (FI)

Private insurance companies that process Medicare Part A claims under contract to HCFA. They apply the Medicare coverage rules to determine the appropriateness of claims and issue payments to providers for the government.


The Health Care Financing Administration, an agency within the U.S. Department of Health and Human Services that administers the Medicare and Medicaid programs.

institutional review board (IRB)

A committee or board associated with a specific institution, constituted according to rules set by the U.S. Department of Health and Human Services, responsible for reviewing, approving, and monitoring research studies involving human beings to be carried out in that institution. Review focuses mainly on the ethics of the proposed research, the informed consent process, and other issues related to study participants.

intention-to-treat (analysis)

An intention-to-treat analysis is one in which outcomes for all the participants in a trial are analyzed according to the intervention to which they were allocated, whether they received it or not. Intention-to-treat analyses mirror the noncompliance and treatment changes that are likely to occur when the intervention is used in practice, and eliminate the potential effect introducing attrition bias by excluding some participants from the analysis.

Investigational Device Exemption (IDE)

An exemption given by the FDA to the manufacturer of a new medical device or to an independent investigator permitting evaluation of the device in human beings in specified studies under specified conditions. The studies are intended to produce information required for approval of the device for marketing.

Investigational New Drug Exemption (IND)

An exemption given by the FDA to the manufacturer of a new drug or to an independent investigator

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