Clinical Pharmacology · MU Sofia

19. Pharmacoeconomics: Definition, principles: perspective, duration, modeling, compliance.

Explains pharmacoeconomics as a way of comparing the costs and consequences of alternative drug treatments under limited resources. Walks through comparison of alternatives, how the choice of perspective changes which costs count, and the time horizon with discounting. Covers decision-tree and Markov modelling with a worked expected-cost example, the effect of patient adherence, and the range of outcome types.

Inside: 2 sections · 1 table · 15 flashcards · 3 min

Topic 19 of 30 in the MU Sofia syllabus for Clinical Pharmacology (Medicine, Year 5). The free AceMed note covers it in 2 sections, about 359 words (3 min of reading), with 15 flashcards.

In this note

  1. Introduction
  2. Key principles

Introduction

Pharmacoeconomics applies economic methods to compare the costs and consequences of alternative drug treatments, to help decide how to use limited healthcare resources. Resources are limited while demand is not, so the aim is the best health outcome for the money available.

Key principles

1. Comparison of alternatives

A pharmacoeconomic evaluation always compares at least two options, counting not only the price of the drug but all related costs: hospital days, tests, devices, treatment of adverse reactions and of treatment failure.

2. Perspective (whose costs?)

The same drug can be cost-saving from one perspective and costly from another, so the perspective must be stated.

3. Duration (time horizon)

  • The analysis must last long enough to capture all important costs and outcomes (for chronic diseases often years or a lifetime).
  • Future costs and benefits are discounted (typically 3–5% a year), because money and health now are valued more than later.

4. Modelling

When trials are too short or do not include all comparators, results are extended with models. The commonest is the decision tree; Markov models are used for chronic diseases.

Example: drug A costs 110 and works in 90% of patients; drug B costs 90 and works in 70%. Treatment failure costs 210 more. Expected cost: A = 0.9 × 110 + 0.1 × 210 = 120; B = 0.7 × 90 + 0.3 × 210 = 126. The dearer drug is the cheaper choice overall.

  • Sensitivity analysis tests how the conclusion changes when uncertain values (prices, efficacy) vary.

5. Compliance (adherence)

Trials report efficacy under ideal adherence. In practice patients often take less than prescribed, so real effectiveness is lower and costs per outcome higher. Simple regimens (once daily, fixed combinations) improve adherence and can be more cost-effective even when the drug is dearer.

6. Outcomes

  • Clinical outcomes (deaths, strokes avoided), surrogate markers (BP, HbA1c, LDL, FEV₁), humanistic outcomes (quality of life) and economic outcomes (costs saved).
  • Data should come from RCTs and meta-analyses; results of pharmacoeconomics are international in method but national in result (prices differ).

A dearer drug can be the cheaper choice once failures, adverse reactions and hospital days are counted: always compare total costs and outcomes.

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