Dictionary

L

Label ExtensionTermIndication Extension, Approved-Use Extension, Label Expansion

An expansion of a drug's officially approved use to cover an additional population, indication, or dosing regimen not in its original approval.

Laboratory DataTermLab Data, Lab Test Results

Information derived from clinical laboratory testing, such as blood chemistry or biomarker assays, used to assess physiological status or treatment response.

Laboratory Information SystemTermLIS, Lab Information System

A specialist software system managing laboratory testing workflows, from sample tracking through result reporting, integrated with health records.

Laboratory OutcomeTermLab Outcome, Lab-Based Outcome, Biochemical Response, Biochemical Marker Response, Laboratory Response

A clinical outcome derived from laboratory testing of blood, urine, or other biological samples, assessing physiological status or treatment response.

Labour EfficiencyTermLabor Efficiency, Staff Efficiency

A measure of how effectively an organisation uses staff time and effort to generate patient care activity, avoiding wasteful workforce use.

Landmark AnalysisConceptLandmark Method, Landmark Survival Analysis

Landmark analysis is a survival method that starts follow-up at a set time, keeps only patients still event-free then and groups them by their status then.

Language BarrierTermLinguistic Barrier, Communication Barrier

An obstacle to healthcare arising from a mismatch between a patient's primary language and that used by providers or health materials.

Language BiasConcept

Language bias is a reporting bias in which a study's language of publication depends on its results, so reviews limited to English can misstate effects.

Large Group MarketTermLarge Employer Market, Large Group Insurance

The insurance market segment serving employers above a defined size threshold, often with greater flexibility in plan design and pricing.

Large Simple TrialConcept

A large simple trial randomises thousands of patients with simple entry rules and minimal data to detect moderate effects on death or serious disability.

Last Observation Carried ForwardConceptLOCF, Carry-Forward Imputation

Last observation carried forward (LOCF) fills missing trial follow-up values with each participant's last observed value, assuming no change after dropout.

Last-Line TreatmentTermLast-Line Therapy, End-of-Line Treatment

The final treatment option considered after all other appropriate therapies have been exhausted or have failed to control disease.

Late AdopterTermLaggard, Late Majority

An individual or organisation beginning to use a new innovation relatively late in its diffusion, often facing greater scepticism or barriers.

Late EffectsTermLong-Term Sequelae, Delayed Treatment Effects

Health problems arising months or years after cancer treatment ends, resulting from the lasting impact of the disease or its treatment.

Latent Class AnalysisConceptLCA, Mixture Modelling

Latent class analysis (LCA) finds unobserved patient subgroups from patterns in categorical data, such as recorded conditions or diagnostic test results.

Latent Class ModelConceptLCM

A statistical model that assumes a population consists of unobserved subgroups with distinct preferences, estimating both each subgroup's traits and individual membership probability.

Latent Growth ModelConceptLatent Growth Curve Model, Growth Trajectory Model

A latent growth model is a structural equation model treating each patient's starting level and rate of change in repeated health scores as latent factors.

Latent PeriodTermLatency Period, Pre-Infectious Period

The interval between exposure to an infectious agent and the point an infected person becomes capable of transmitting it to others.

Latent Transition AnalysisConcept

Latent transition analysis (LTA) is a longitudinal latent class method that estimates how patients move between unobserved health or behaviour states.

Latent VariableConceptLatent Construct, Unobserved Variable

A latent variable is an unobserved quantity, such as health-related quality of life or preference class membership, estimated from observed indicators.

Latin Hypercube SamplingConcept

Latin hypercube sampling is a stratified Monte Carlo design that draws each input to a health economic model once from each of n equally likely intervals.

Launch PriceTerm

The initial price at which a manufacturer introduces a new drug to a specific market, shaping both initial access and later reference pricing.

Launch PricingTerm

The overall strategy and process by which a manufacturer determines a new treatment's initial market price across its target markets.

Launch SequencingTermLaunch Timing

The strategic planning of the order a manufacturer introduces a treatment across national markets, influenced by international reference pricing linkages.

Launch StrategyTermProduct Launch Strategy, Go-to-Market Strategy, Launch Plan

The comprehensive plan a manufacturer develops for introducing a new treatment to market, covering pricing, market access, and evidence generation activities.

Law of Large NumbersConceptLLN, Law of Averages

The law of large numbers says the average of independent patient costs or simulation draws settles on the true mean as more are added.

Lead IdentificationTerm

An early drug discovery stage in which promising compounds from initial screening are characterised and prioritised for further development based on potency and selectivity.

Lead OptimisationTermLead Optimization

A drug discovery stage in which chemists modify a promising compound's structure to improve potency, selectivity, and pharmacokinetics before preclinical testing.

Lead Time BiasTerm

A bias in screening evaluations where earlier diagnosis appears to extend survival but only lengthens awareness of diagnosis, without delaying underlying disease progression.

League TableTerm

A table from a network meta-analysis displaying every treatment's estimated relative effect against every other treatment, organised for pairwise lookup.

League Table ConstructionTermICER Ranking, League Table Assembly

The process of assembling and ranking incremental cost-effectiveness ratios from multiple separate studies into a single comparative table to guide resource allocation.

Leakage RateTermBenefit Leakage, Targeting Leakage

The proportion of a targeted programme's total benefits that reach individuals outside its intended eligible population.

Lean HealthcareTerm

The application of lean management principles, from manufacturing, to healthcare process improvement, systematically identifying and eliminating waste in care delivery.

Lean MethodologyTermLean, Lean Management

A management approach, from manufacturing, focused on maximising value for the end customer while systematically minimising waste within a process.

Least Squares ApproximationConceptLeast Squares, Ordinary Least Squares

Least squares approximation estimates the coefficients of a chosen model by minimizing the sum of squared residuals between observed or target values and the corresponding model values.

Leave-One-OutConcept

Leave-one-out cross-validation tests a cost or risk prediction model by refitting it without each observation in turn and predicting the one left out.

Left CensoringConcept

Left censoring occurs when a patient's event, such as disease onset, is known only to have happened before the first observation, at an unknown time.

Left TruncationConceptDelayed Entry, Late Entry

Left truncation (delayed entry) occurs when people join a survival analysis risk set after time zero and are observed only if still event free at entry.

Legal EvidenceTermLegal Documentation, Legal-Implications Evidence

Documentation addressing the legal implications of an assessment decision, such as compliance with anti-discrimination or procedural fairness law.

Legal FeasibilityTermLegal Viability, Legal-Framework Feasibility

An assessment of whether a proposed policy is consistent with existing legal frameworks, or would require new legislative authority to implement.

Legal ReviewTermLegal Examination, Legal Compliance Review

An examination of a proposed assessment decision or process to assess compliance with applicable legal requirements.

Length BiasTerm

A bias in screening evaluations arising because screening preferentially detects slower-growing cases that stay detectable longer, while aggressive cases are more often missed.

Length of StayTermLOS, Hospital Stay Duration

The total duration of a single patient's hospital admission, from the date of admission to the date of discharge.

Length Of Stay ManagementTermLOS Management, Stay Reduction

Strategies used to appropriately manage and, where clinically suitable, reduce hospitalisation duration, through care coordination and discharge planning.

Length of Stay ReviewTermLOS Review, Stay Duration Audit

An evaluation of a hospitalisation's duration relative to what would typically be expected, identifying efficiency opportunities or investigating prolonged stays.

LevelTerm

A specific value an attribute can take within a discrete choice experiment, such as a waiting time of two weeks versus six.

Level of DetailTermDetail Level, Model Resolution

The degree of granularity with which a decision-analytic model represents disease states, events, and population characteristics.

Level of EvidenceTermEvidence Level, Evidence Hierarchy Rank, Hierarchy of Evidence, Evidence Hierarchy

A classification ranking a study design's strength based on its susceptibility to bias, placing randomised trials above case reports or opinion.

Levels of CareTermCare Levels, Tiers of Care

In health systems, the tiers at which care is organised and accessed, from primary through secondary and tertiary to quaternary care, structuring referral pathways and resource use.

Leverage PointConceptLeverage Observation, Unusual Predictor Point

An observation with an unusual combination of predictor values, distinct from the bulk of the data, capable of disproportionately influencing a regression model.