Dictionary

O

Obesity EconomicsTermEconomics of Obesity, Obesity Cost of Illness

The application of health economic evaluation to obesity prevention and treatment, spanning lifestyle intervention, medication, and bariatric surgery.

Obesity Prevalence RateTermObesity Rate, Population Obesity Level

A measure of the proportion of a population classified as obese based on standardised body mass index criteria.

Objective Response RateConceptORR, Overall Response Rate

Objective response rate is the proportion of participants in a prespecified analysis population who achieve a complete or partial tumor response according to defined response criteria during the assessment period, with any confirmation requirement stated.

Oblique RotationConceptCorrelated-Factor Rotation, Promax Rotation

A factor analysis technique transforming a solution into a more interpretable structure while allowing the resulting factors to correlate with each other.

Observational DataTermNon-Experimental Data, Non-Interventional Data

Data collected without the researcher assigning participants to a specific exposure or treatment, instead observing naturally occurring patterns.

Observational DesignTermNon-Experimental Design, Observational Study Design

A broad category of study designs, including cohort, case-control, and cross-sectional studies, in which outcomes are observed without assigning participants to an intervention.

Observational StudyConceptNon-Interventional Study, Observational Research

A study that observes exposures and outcomes without investigator assignment of the exposure under investigation, using a specified design to describe patterns or assess associations and, under additional assumptions, causal effects.

Observed-to-Expected RatioConceptO/E Ratio, Observed-Expected Ratio

A measure comparing a provider's actual observed outcomes against statistically expected numbers given patient severity, above one meaning worse than expected.

Observer-Reported OutcomeTermObsRO, Proxy-Reported Outcome

A clinical outcome reported by someone other than the patient or a clinician, such as a carer of a patient who cannot self-report.

Obsolete TechnologyTermOutdated Technology, Superseded Technology

A technology superseded by a more effective, safer, or more cost-effective alternative, such that its continued routine use is inappropriate.

Obstetrics EconomicsTermObstetric Care Economics, Childbirth Economics

The application of health economic evaluation to pregnancy and childbirth care, covering prenatal screening, labour and delivery, and postpartum care.

Occupancy RateConceptBed Occupancy, Bed-Occupancy Percentage

Occupancy rate (bed occupancy) is the percentage of a hospital's available staffed beds that hold inpatients, averaged from daily bed counts over a period.

Occupational EpidemiologyTermWorkplace Epidemiology, Occupational-Exposure Epidemiology

A branch of epidemiology studying the relationship between workplace exposures and health outcomes among working populations.

Occupational Health PolicyTermWorkplace Health Policy, Occupational Safety Policy

Government or organisational policy addressing workplace health and safety risks, covering regulatory standards and workers' compensation programmes.

Occupational Therapy EconomicsTermOT Economics, Occupational Therapy Cost

The application of health economic evaluation to occupational therapy, which helps patients regain daily activity skills after illness, injury, or disability.

Odds RatioConceptOR, Odds Relative Measure

A measure comparing the odds of an outcome in one group to the odds in another, common in case-control studies and logistic regression.

Oesophageal EconomicsTermEsophageal Economics, Oesophageal Disease Economics

The application of health economic evaluation to oesophageal conditions, including reflux disease, oesophageal cancer, and swallowing disorders.

Off-Label UseTermOff-Label Prescribing, Unlicensed Use

The prescribing of an approved drug for a condition, population, or dosing regimen not specifically included in its official regulatory approval.

OIG AuditTermOffice of Inspector General Audit, OIG Compliance Audit

A review by the US Office of Inspector General examining a healthcare organisation's billing or compliance for potential fraud, waste, or abuse.

Oligopoly BehaviourTermOligopolistic Competition, Oligopoly Conduct

The strategic pricing and output decisions of firms in a market dominated by a small number of sellers who must anticipate rivals' responses.

Oncology EconomicsTermCancer Economics, Economics of Cancer

The broad application of health economic evaluation to cancer prevention, screening, diagnosis, and treatment.

Oncology Value FrameworkTermASCO Value Framework, ESMO-MCBS

A structured tool from professional oncology societies combining clinical benefit, toxicity, and cost into a single comparative score for assessing treatment value.

One Health EconomicsTermOneHealth Economics, Planetary Health Economics

The application of health economic methods to problems spanning human, animal, and environmental health simultaneously, such as zoonotic disease control.

One-Stage Meta-AnalysisTermOne-Step Meta-Analysis, IPD One-Stage Model

An individual patient data meta-analysis analysing combined patient-level data from all studies within a single unified statistical model.

One-Tailed TestTermOne-Sided Test, Directional Test

A hypothesis test assessing evidence for an effect in only one specified direction, requiring strong prior justification for that direction.

One-Time TreatmentTermSingle-Administration Therapy, Durable One-Shot Treatment

A therapy, such as certain gene or cell therapies, given only once and intended to produce a durable or permanent clinical benefit.

One-Way SensitivityConceptUnivariate Sensitivity, Single-Parameter Sensitivity

A deterministic sensitivity analysis that varies one model input across a specified range while keeping the remaining inputs at their base-case settings, then recalculates the model outcome and any decision threshold.

One-Way Sensitivity AnalysisConceptOWSA, Univariate Sensitivity Analysis

One-way sensitivity analysis (OWSA) varies one model input at a time, holding the rest at base case, to show which inputs drive cost-effectiveness results.

Only in ResearchTermOIR, Research-Only Recommendation

A recommendation category indicating a technology should be funded only within a formal research study, rather than routine clinical practice.

Open Label StudyTermOpen-Label Trial, Unblinded Study

A trial design in which both participants and researchers know which treatment each person is receiving, without any blinding of assignment.

Open-Source ModelTermOpen Model Code, Publicly-Available Model

A model whose complete code and structure are publicly available, letting anyone review, replicate, or adapt it without special permission.

Operating BudgetTermRecurrent Budget, Running-Costs Budget

A budget covering the day-to-day revenues and expenses required to run an organisation's ongoing operations.

Operating CostTermRunning Cost, Recurrent Cost

The recurring cost of an organisation's ongoing operations, such as staffing, supplies, and utilities, as distinct from one-off capital investment.

Operating MarginTermOperating Profit Ratio, EBIT Margin

A financial ratio calculated as operating income divided by revenue, showing the proportion remaining after operating expenses but before non-operating items.

Operating Room ManagementTermOR Management, Theatre Management

The processes used to schedule, coordinate, and optimise a hospital's surgical suite resources, covering case scheduling and turnover time.

Operational AnalyticsTermOperations Analytics, Hospital Operations Analytics

The application of data analysis to a healthcare organisation's operational processes, such as patient flow and staffing, identifying efficiency opportunities.

Operational EfficiencyTermOperating Efficiency, Process Efficiency

A measure of how effectively an organisation converts available resources into patient care activity, avoiding unnecessary waste or delay.

Operational WasteTermProcess Waste, Operational Inefficiency

Inefficiencies within an organisation's day-to-day operations that consume resources without producing corresponding value, such as unnecessary delays.

Ophthalmology EconomicsTermEye Care Economics, Vision Health Economics

The broad application of health economic evaluation to eye conditions, from cataracts and glaucoma to complex retinal disease.

Opinion LeaderTermKOL, Thought Leader

An individual whose views carry particular influence over peers' attitudes and practices, often leveraged within implementation strategies to promote adoption.

Opioid Use EconomicsTermOpioid Economics, Opioid Crisis Economics

The application of health economic evaluation to opioid use disorder, covering medication-assisted treatment, overdose prevention, and broader public health responses.

Opportunistic ScreeningTermCase-Finding Screening, Ad Hoc Screening

A screening approach offering testing when an individual happens to present for an unrelated visit, rather than through systematic invitation.

Opportunity CostConceptForgone Benefit, Alternative Cost

Opportunity cost is the value of the best alternative given up when a resource is put to one use; in health care, usually health lost elsewhere.

Opportunity Cost AnalysisTermOpportunity-Cost Appraisal, Foregone-Benefit Analysis

A form of analysis explicitly estimating the health or value forgone elsewhere in a system when resources are allocated to a specific intervention.

Opportunity Cost AssessmentTermOpportunity-Cost Evaluation, Displacement Assessment

The process of estimating what health benefits or other value are displaced when a health system commits resources to a new intervention.

Opportunity Cost CriterionTermOpportunity-Cost Decision Rule, Health-Maximising Criterion

A decision rule stating that an intervention should only be adopted if the value it produces exceeds the value of resources it displaces elsewhere.

Opportunity LossTermEOL, Loss from Wrong Decision

The difference in value between the outcome of the optimal decision and the outcome of the decision actually made under uncertainty.

Opt-Out OptionTermPresumed Consent, Automatic Enrolment

An alternative in a discrete choice experiment letting respondents select neither presented option, representing a choice to keep current circumstances.

Optimal Sample SizeConceptENBS-Based Sample Size, Efficient Sample Size Choice

A study sample size selected to meet a stated design objective, such as adequate power or precision, or to maximise the expected value of information after accounting for research costs and decision delays.

Optimal Study DesignTermVOI-Optimal Design, Efficient Research Design, Study Design Optimisation

The combination of research characteristics, such as sample size and follow-up duration, that maximises the expected net benefit of sampling for a budget.