The Role of Health Economic Evaluation in National Drug Selection and Decision-Making

Introduction

Health systems worldwide confront an increasingly complex matrix of clinical innovation, economic pressure, and population need. Central to resolving this tension is Health Economic Evaluation (HEE)—a structured methodology that integrates clinical effectiveness with economic rationality. Nowhere is its relevance more pronounced than in the development and stewardship of the National List of Essential Medicines (NLEM). This curated list of medicines serves as the backbone of public pharmaceutical access policies in many countries, including Thailand, where fiscal prudence must align with equity and population health goals.

This article dissects the multifaceted roles of HEE in NLEM decision-making. We explore the conceptual foundations of Health Economics and Outcomes Research (HEOR), delineate its analytic components, and unpack the evidence pipelines that feed policy-level economic appraisal.

I. Foundations of Health Economic Evaluation: Defining the Terrain

1. Health Economics and Outcomes Research (HEOR): Twin Pillars

Health Economics investigates how resources are allocated within the healthcare system, focusing on the costs (inputs) and consequences (outputs) of medical interventions. Outcomes Research, meanwhile, examines how healthcare affects patient-centered outcomes across three domains:

Clinical Outcomes – Measures such as mortality, disease progression, treatment efficacy, and functional recovery.
Economic Outcomes – Include direct (e.g., drug costs, hospitalization) and indirect costs (e.g., productivity loss, caregiver burden).
Humanistic Outcomes – Encompass patient-reported quality of life, satisfaction, and social participation impacts.

Collectively, these domains provide a 360-degree evaluation of a therapy’s real-world value, moving beyond narrow efficacy measures.

II. Rationale and Scope: Why Health Economic Evaluation Is Indispensable

Decision-makers—including health ministries, HTA bodies, and hospital formularies—require more than clinical trial data to make resource allocation decisions. The rationale for HEE stems from several foundational truths:

RCTs offer limited generalizability: Many RCTs are tightly controlled, exclude multimorbidity, and underrepresent marginalized populations.
Clinical endpoints ≠ Patient value: A statistically significant biomarker change (e.g., LDL reduction) may not equate to better survival or function.
Healthcare is resource-constrained: Economic evaluations provide tools like Incremental Cost-Effectiveness Ratios (ICERs) to assess opportunity costs.
Patient-centered metrics matter: Incorporating HRQOL and Patient-Reported Outcomes (PROs) ensures alignment with what patients experience and prioritize.

In short, HEE helps answer not only “Does it work?” but “Is it worth it?”—an essential filter when choosing which medicines enter national formularies.

III. Health Economic Evaluation in the NLEM: Institutional Logic and Criteria

1. Thailand's Three-Fund Architecture

Thailand's universal health system operates through three public insurance schemes:

Universal Coverage Scheme (UCS) – Covers ~75% of the population.
Civil Servant Medical Benefit Scheme (CSMBS) – For government employees (~8%).
Social Security Scheme (SSS) – For formal sector workers (~17%).

All three are anchored by the NLEM, ensuring baseline access to essential drugs. Medicines not on the NLEM may face restricted access, higher patient out-of-pocket costs, or complete exclusion from coverage.

2. NLEM Selection Process: Evidence Meets Governance

The pathway from proposal to listing involves:

Topic nomination: From clinicians, researchers, or health professionals.
Prioritization: Based on public health burden, unmet need, and feasibility.
Health Technology Assessment (HTA): Led by bodies like HITAP or HEWG, which compile evidence on:
- Efficacy and safety (via systematic reviews, meta-analyses)
- Cost-effectiveness (via economic modeling)
- Affordability (budget impact analysis)
- Social and ethical considerations (e.g., equity, vulnerable populations)
Deliberation and listing: The final decision integrates both quantitative metrics (e.g., ICERs) and qualitative deliberations (e.g., feasibility of implementation).

IV. Evidence Inputs to Economic Evaluation: The Data Backbone

Robust economic evaluation hinges on the triangulation of multiple evidence streams:

1. Real-World Evidence (RWE)

Derived from registries, insurance claims, and electronic health records.
Captures actual practice patterns, adherence, and outcomes beyond trial protocols.

2. Clinical Trials (RCTs and Pragmatic Trials)

Provide high internal validity but may lack external validity.
Pragmatic trials score higher on generalizability using tools like the PRECIS-2 framework.

3. Systematic Reviews and Meta-Analyses

Offer consolidated effect sizes and comparative effectiveness insights.

4. Patient-Reported Outcomes (PROs)

Tools like EQ-5D and SF-36 quantify quality of life adjustments for Cost-Utility Analysis (CUA).

5. Budget Impact Analyses (BIAs)

Project the financial impact of adopting a new medicine across population-level use scenarios.

V. Metrics and Methodology: The Language of Economic Evaluation

1. Core Economic Models

Cost-Effectiveness Analysis (CEA): Outcomes in natural units (e.g., life-years gained).
Cost-Utility Analysis (CUA): Outcomes in QALYs; facilitates comparison across diseases.
Cost-Minimization Analysis (CMA): When two interventions are clinically equivalent.
Cost-Benefit Analysis (CBA): Outcomes in monetary terms (e.g., WTP thresholds).

2. The ICER Logic

ICER = \frac{∆ Cost}{∆ Effectiveness (e.g., QALYs)}

Thresholds vary by country. Thailand, for example, uses 1–3× GDP per capita as a cost-effectiveness benchmark, approximately 160,000 THB/QALY.

3. Equity and Ethics Beyond ICER

HEE frameworks in NLEM also embed:

Disease severity weighting
Impact on health equity
Societal burden considerations (e.g., caregiver time, community transmission)

These factors are especially critical when evaluating drugs for rare diseases, pediatric conditions, or marginalized groups.

VI. Practical Example: Inclusion Dynamics in Thai HTA

Stepwise Appraisal in the Thai HTA Ecosystem:

Identification: Clinicians propose a new oncology drug for inclusion.
Review: HITAP evaluates efficacy, safety, and submits cost-utility analysis.
Stakeholder engagement: Involves nine groups, including civil society and economists.
Economic modeling: Combines Thai registry data with global trial outcomes.
Deliberation: Integrates technical analysis with real-world feasibility (e.g., cold chain logistics).
Decision: Final listing with possible use restrictions (e.g., line of therapy, biomarker status).

This iterative, transparent process aligns public spending with maximized health gains.

Conclusion: From Metrics to Meaningful Access

Health economic evaluation is not merely a technical exercise; it is a moral imperative in health governance. By embedding economic, clinical, and humanistic evidence into the decision-making matrix, HEOR ensures that essential medicines policies are both rational and just. As population needs evolve and therapeutic frontiers expand, countries must continually refine their HEOR frameworks to maintain equity, affordability, and scientific integrity in medicine access.

Key Takeaways

HEOR integrates clinical, economic, and patient-centered data to guide national formulary decisions.
Thailand’s NLEM process exemplifies rigorous HTA aligned with UHC principles.
Economic evaluations must combine ICER with affordability, equity, and implementation feasibility.
Real-world data and PROs enhance the external validity and patient relevance of models.
Essential medicines policy is both a scientific and ethical commitment to population well-being.