Evidence-Based Drug Selection: Efficacy, Safety, and Cost

Evidence-based drug selection is the practice of choosing among therapeutic options by weighing the best available evidence of how well a medicine works, how safe it is, and what it costs, alongside the patient's own circumstances and preferences. It applies the framework of evidence-based medicine to the specific question of which drug, if any, to use.

Definition

Evidence-based drug selection is the process of choosing a medication by integrating the best available research evidence on efficacy and safety with clinical judgement, patient values, and considerations of cost, to identify the option whose expected benefit best justifies its risks and resources for the situation at hand.

Scope

This entry covers the conceptual structure of comparing medicines: appraising efficacy and effectiveness evidence, characterizing the harm side of the ledger, and bringing cost and value into the decision. It frames these as appraisal concepts within pharmacy practice and does not provide prescribing recommendations for any drug or condition.

Core questions

• What is the best available evidence that a drug improves outcomes that matter to patients?
• How are the harms of a therapeutic option identified, quantified, and weighed against its benefits?
• How do cost and value enter the choice among comparable options?
• How are population-level evidence and an individual patient's values reconciled in a single decision?

Key concepts

• Efficacy versus effectiveness
• Patient-important outcomes
• Benefit-harm balance
• Adverse drug reactions
• Cost-effectiveness and value
• Formulary and therapeutic interchange
• Deprescribing

Key theories

Evidence-based medicine

The integration of the best available external research evidence with individual clinical expertise and the patient's values and circumstances, applied here to the question of which medicine to choose rather than continuing on tradition or unsystematic experience alone.

Mechanisms

Evidence-based selection proceeds by framing an answerable clinical question, finding and appraising the relevant evidence, and applying it with attention to the individual patient (Sackett, 1996). The benefit side rests on efficacy and effectiveness data, ideally for outcomes that matter to patients. The harm side requires recognizing that adverse drug reactions are common and consequential, and that their definition, diagnosis, and attribution are themselves analytic tasks (Edwards & Aronson, 2000); pooled estimates indicate adverse reactions are a frequent cause of harm among hospitalized patients (Lazarou et al., 1998). Optimization also includes recognizing when a previously appropriate medicine should be stopped, a process formalized as deprescribing (Reeve et al., 2014).

Clinical relevance

The appraisal skills described here are central to clinical pharmacy, therapeutics committees, and formulary work, and to teaching critical evaluation of the drug literature. This entry explains how the comparison among medicines is reasoned and is reference and educational material; it is not a basis for selecting, prescribing, or dosing any drug for an individual.

Epidemiology

Adverse drug reactions are a substantial and partly preventable contributor to morbidity. A meta-analysis of prospective studies estimated that serious adverse drug reactions occur in a meaningful fraction of hospitalized patients, underscoring why the harm side of selection cannot be treated as negligible (Lazarou et al., 1998).

Evidence & guidelines

Evidence-based medicine supplies the overarching method for selection (Sackett, 1996), and condition-specific clinical practice guidelines operationalize it for particular diseases. The systematic literature on deprescribing illustrates how the same evidence-based logic applies to stopping as well as starting therapy (Reeve et al., 2014). Specific formulary and prescribing recommendations are maintained by professional and regulatory bodies and fall outside this reference entry.

History

Although weighing the merits of remedies is ancient, the explicit, systematized appraisal of medicines is recent. The articulation of evidence-based medicine in the 1990s reframed therapeutic choice as the deliberate integration of appraised evidence with clinical expertise and patient values (Sackett, 1996). Growing recognition of adverse drug reactions as a major harm (Lazarou et al., 1998; Edwards & Aronson, 2000) and, later, the formalization of deprescribing (Reeve et al., 2014) broadened selection from a one-time choice into an ongoing optimization.

Debates

How heavily should cost weigh against efficacy and safety?

Integrating cost and value into selection is widely accepted in principle, but how explicitly cost should constrain choices for an individual patient, versus at the formulary or policy level, remains a contested judgement.

Key figures

• David Sackett
• R. Brian Haynes
• Jeffrey Aronson

Seminal works

• sackett-1996
• lazarou-1998
• edwards-2000

Frequently asked questions

What is the difference between efficacy and effectiveness in drug selection?

Efficacy refers to how well a drug works under the controlled conditions of a trial, while effectiveness refers to how well it works in ordinary practice; both inform selection, and a gap between them can change which option is preferred for real-world use.

Does evidence-based drug selection ignore the individual patient?

No. Evidence-based medicine explicitly combines the best research evidence with clinical expertise and the individual patient's values and circumstances, so population evidence informs but does not by itself dictate the choice.