Dictionary

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Organ ResponseTermOrgan-Level Response, Organ-Specific Improvement

A biomarker-based outcome measure indicating improvement in a specific organ's function or structure affected by disease, requiring disease-specific validated criteria.

Organisational EvidenceTermService-Delivery Evidence, System-Impact Evidence

Information addressing how an assessment decision might affect broader operational aspects of a health system, such as staffing or infrastructure needs.

Organisational ReviewTermService Impact Review, Delivery-System Review

An evaluation of the organisational and operational implications of adopting a new technology, examining infrastructure, training, and workflow needs.

Orphan DiseaseTermRare Condition, Rare Disorder

A disease affecting a very small number of people, below a specified population threshold, historically receiving limited treatment development investment.

Orphan DrugTermRare Disease Drug, Orphan Medicine

A treatment developed specifically for a rare disease below a specified population threshold, eligible for special regulatory designation and incentives.

Orphan Drug DesignationTermODD, Special Regulatory Status, Orphan Designation

A regulatory status for a rare disease treatment, giving development incentives such as tax credits, fee waivers, and extended market exclusivity.

Orphan Drug IncentivesTermRare-Disease Incentives, Orphan Development Incentives

The regulatory and financial benefits offered to manufacturers developing rare disease treatments, including trial expense tax credits and extended exclusivity.

Orphan Drug PricingTermOrphan Pricing, Rare-Disease Drug Pricing

The pricing strategies applied to rare disease treatments, frequently priced far higher per patient than common-condition treatments given the smaller patient population.

Orphan Drug ThresholdTermOrphan Threshold, Higher Rare-Disease Threshold

The population size threshold defining a disease as rare or orphan for regulatory designation, varying somewhat across countries and jurisdictions.

Orphan ExclusivityTermOrphan Market Exclusivity, Orphan Drug Exclusivity

A market exclusivity period following orphan drug approval during which regulators generally will not approve a similar competing product for the same rare indication.

Orthogonal DesignConceptOrthogonal Array Design, Uncorrelated Design

An experimental design for a choice experiment in which attribute levels are varied independently, so each attribute's effect on preference can be separated statistically.

Orthogonal RotationConceptUncorrelated-Factor Rotation, Varimax-Type Rotation

A factor analysis technique transforming a solution into a more interpretable structure while constraining the resulting factors to remain uncorrelated.

OsteoarthritisTermOA, Degenerative Joint Disease

A degenerative joint condition involving progressive cartilage breakdown, commonly affecting weight-bearing joints such as the knee and hip.

Out-of-NetworkTermOON, Out-of-Plan Provider

A designation for providers without a contractual agreement with a specific plan, typically resulting in higher cost-sharing or no coverage.

Out-of-Network ReferralTermOON Referral, External Referral

A referral to a provider without a contractual relationship with the patient's insurance plan, typically resulting in higher cost-sharing or no coverage.

Out-of-Pocket CostConceptOOP Cost, Patient Out-of-Pocket Spending

The amount a patient or household pays directly for health care without third-party reimbursement, including applicable cost sharing and uncovered care.

Out-of-Pocket MaximumTermOOP Maximum, Maximum Out-of-Pocket

The highest total amount an insured person will pay for covered costs within a period, beyond which the plan covers everything further.

Out-of-Pocket ModelTermOOP Health System, Direct-Payment Health System

A financing arrangement in which patients pay directly for care at the point of service, with little or no pooled prepayment to spread risk.

Out-of-Pocket PaymentTermOOP Payment, Direct Patient Payment

A general term for healthcare spending paid directly by a patient, rather than through insurance, covering cost-sharing and uncovered services.

Out-of-Pocket ShareTermOOP Share, OOP Financing Share

The proportion of total healthcare expenditure within a country paid directly by patients, rather than through pooled financing mechanisms.

Out-of-SampleTermHoldout Sample, Test-Set Evaluation

Describing performance calculated using data not used in a model's original construction, giving a more realistic assessment of likely real-world accuracy.

Outbreak CostTermCost of Outbreak, Epidemic Cost

The total economic burden of an infectious disease outbreak, covering direct healthcare costs, public health response spending, and productivity losses.

Outbreak InvestigationTermEpidemic Investigation, Field Epidemiology Investigation

A systematic epidemiological process identifying an outbreak's source, mode of transmission, and scope, typically conducted under time pressure.

Outcome AssessmentTermOutcomes Measurement, Outcome Evaluation

The measurement and evaluation of health outcomes resulting from care, treated as one of the three linked dimensions of quality alongside structure and process.

Outcome MeasureConceptOutcome Metric, Endpoint Measure

A specified instrument, observation or data rule used to quantify a health, care or resource outcome for a defined population and time point.

Outcome QualityTermOutcome Dimension of Quality, Results Quality

A healthcare quality dimension focused on actual care results, such as survival or functional status, unlike structural or process quality.

Outcome Quality IndicatorTermOutcome Indicator, Results Quality Indicator

A specific, measurable metric assessing actual health results, such as mortality or complications, used to evaluate a provider's clinical performance.

Outcome ReportingTermResults Reporting, Endpoint Reporting

The practice of documenting and disclosing a study's results, ideally consistent with what was originally planned before results were known.

Outcome Reporting BiasTermSelective Outcome Reporting, Outcome Switching

Bias arising when the outcomes reported in a published study are selected based on the direction or significance of their results, not as originally planned.

Outcome-Based BudgetTermResults-Based Budget, Outcome-Linked Budget

A budgeting approach that allocates funds according to expected or achieved health outcomes rather than historical spending or input costs.

OutcomesTerm

Outcomes is the area of health economics that measures and values the health consequences an economic evaluation counts, from survival and symptoms to quality-adjusted life years.

Outcomes ResearchConcept

Outcomes research, often joined with health economics as HEOR, studies the end results of health care, such as survival, function and quality of life.

Outcomes-Based ContractTermValue-Based Contract, Results-Based Agreement

A formal agreement in which some or all of a treatment's payment is contingent on it achieving predefined clinical outcomes in practice.

Outcomes-Based PaymentTermPay-for-Outcomes, Results-Based Payment

A reimbursement arrangement in which some or all of a manufacturer's payment depends on the treatment achieving a predefined clinical outcome in actual practice.

Outer LoopTermParameter Loop, First-Level Loop

The portion of a nested simulation sampling parameter values that remain fixed while a complete inner loop simulation runs beneath it.

OutlierTermExtreme Value, Anomalous Observation

An observation differing markedly from other values in a dataset, either from genuine unusual variation or a measurement or entry error.

Outlier IdentificationTermOutlier Detection, Anomaly Detection

The process of identifying data points, cases, or providers whose performance substantially deviates from an expected pattern, flagging further investigation.

Outlier PaymentTermHigh-Cost Case Payment, Outlier Adjustment

A supplemental payment made in addition to standard prospective payment for a case whose actual cost or stay substantially exceeds expectations.

Outpatient CostTermAmbulatory Cost, Outpatient Care Cost

The expense of healthcare services delivered without an overnight hospital stay, such as clinic visits, diagnostic testing, and same-day procedures.

Outpatient VisitsTermAmbulatory Visits, Clinic Visits

The total number of patient encounters at a facility without formal hospital admission over a defined period, an ambulatory utilisation measure.

Output InterfaceTermResults Interface, Model Results Panel

The component of a health economic model that presents its results, such as cost-effectiveness ratios, in a format accessible to users.

Output MaximisationTermOutput Maximization, Output-Oriented Efficiency

An objective in production theory of achieving the greatest possible output from a given set of inputs.

Output-Based FinancingTermOutput-Linked Financing, Volume-Based Financing

A financing approach tying payments to providers or programmes to the volume or type of services delivered, rather than a fixed budget.

Overall Hospital RatingTermHospital Star Rating, Summary Hospital Score

A summary star rating assigned to a hospital based on aggregate performance across multiple quality and experience measures.

Overall SurvivalConceptOS, Total Survival

Overall survival is the time from a prespecified origin, such as randomization, diagnosis, or treatment initiation, until death from any cause, with participants not known to have died censored at their last date known alive.

OverconfidenceTermOver-Precision, Excessive Certainty

A cognitive bias in which individuals, including expert forecasters, express excessive certainty, producing judgements narrower than their actual accuracy would justify.

OverfittingConceptOver-Fitting, Model Overfit

A situation in which a model is fit too closely to the noise in its training data, performing poorly on new, independent data.

Overhead CostTermIndirect Overhead, Overhead Expense

A cost that supports an organisation's overall operations but cannot be directly attributed to a specific service or department, such as administration.

Override RateTermAlert Override Frequency, Alert Dismissal Rate

The proportion of computerised clinical alerts a provider dismisses without following the recommended action, a key metric for alert calibration.

OverutilizationTermExcess Utilisation, Service Overprovision, Overuse

The use of healthcare services beyond what is clinically necessary or beneficial, an inefficient use of health system resources.