Efficacy refers, in the context of clinical trials, to the demonstrated effectiveness of a medicinal product or medical device under controlled study conditions. It is the central authorisation criterion for new therapies and is systematically measured and statistically demonstrated in controlled clinical trials \u2013 typically in Phase II and Phase III. Efficacy is to be distinguished from effectiveness, which describes the effect under real-world, everyday conditions. This distinction is fundamentally important for study design, regulatory assessment, and the subsequent benefit assessment carried out by payers.<\/p>\n
Efficacy is measured under ideal, controlled conditions: a strictly selected study population, optimal participant compliance, close medical supervision, and fully standardised treatment procedures. Confounding factors are minimised through randomisation and blinding, so that a direct causal relationship between the intervention and the observed effect can be established. Efficacy therefore answers the question of whether an agent can work under these ideal conditions \u2013 not whether it also does so in an unselected patient population.<\/p>\n
Effectiveness, by contrast, is captured in real-world evidence studies or non-interventional studies and describes how well the medicinal product works in a broad, heterogeneous patient population in everyday clinical practice. The difference between the two measures can be substantial. A medicinal product with high efficacy may show markedly lower effectiveness in practice, for example owing to limited adherence, poor compliance, or the treatment of patients with comorbidities who were excluded from the clinical trial. This distinction is regularly discussed in the early benefit assessment under AMNOG in Germany.<\/p>\n
Regulatory authorities such as the EMA and the FDA require proof of a positive benefit-risk assessment for the approval of a new medicinal product. Demonstration of efficacy is, alongside safety and quality, one of the three pillars of every marketing authorisation dossier. The requirements are set out in detail in guidelines from the ICH, the EMA and the FDA, for example in ICH E8 on general study planning and in indication-specific guidelines, which prescribe different endpoints depending on the therapeutic area.<\/p>\n
Within the Marketing Authorisation Application, applicants must submit comprehensive clinical data demonstrating efficacy in the target population. Not only primary endpoints are assessed, but also secondary and exploratory endpoints as well as subgroup analyses, in order to evaluate the consistency of the demonstration of efficacy across different patient groups. Authorities also examine whether the study population is representative of the later target population and whether the chosen endpoints are clinically relevant. An overly homogeneous study population may increase statistical power but limit the external validity of the results.<\/p>\n
The operationalisation of efficacy takes place via clinical endpoints, which must be defined in advance in the clinical study protocol and published in the study registration. Primary endpoints are the most important measure of efficacy and form the basis for the main statistical analysis. Typical endpoints in oncology are overall survival, progression-free survival and overall response rate. In other indications, validated symptom scores, laboratory values, or functional measurements are used.<\/p>\n
Surrogate endpoints \u2013 for example a biomarker-based laboratory value instead of a clinical outcome \u2013 can be accepted in justified cases, but must be biologically and clinically validated. Statistical analysis generally follows the principle of the intention-to-treat analysis as the primary analysis population, supplemented by a per-protocol analysis as a sensitivity analysis. For confirmatory assessment, a predefined control of the alpha error is required. Where there are multiple primary endpoints, a multiplicity correction must be anchored in the statistical analysis plan.<\/p>\n
In Phase I trials, safety and tolerability are the primary focus; initial indications of efficacy are captured exploratorily. Phase II trials serve dose finding and provide initial efficacy data that are crucial for planning the pivotal Phase III trials. Only in Phase III is efficacy demonstrated confirmatorily with the required statistical power. Inadequate planning of Phase II trials \u2013 particularly regarding the choice of primary endpoint or sample size \u2013 can result in Phase III trials being based on incorrect assumptions and failing. Mediconomics supports sponsors in study planning and endpoint selection from early phases onward, in order to minimise these risks. This includes scientific advice on study design, the selection of valid endpoints in coordination with authorities, and statistical sample-size planning, ensuring that the trial is adequately powered to demonstrate a clinically relevant effect.<\/p>\n
What is the difference between efficacy and effectiveness in German usage?<\/strong><\/p>\n The terms are often used synonymously. In the scientific and regulatory context, efficacy stands for the demonstration of effect under controlled study conditions, while the German term “Wirksamkeit” can encompass both efficacy and effectiveness. In authorisation dossiers, the English term efficacy is generally used to make the distinction clear.<\/p>\n How many trials are required to demonstrate efficacy?<\/strong><\/p>\n The EMA and FDA generally require two independent, pivotal clinical trials with consistent results. For rare diseases or under conditional marketing authorisation, a single, well-controlled trial may also suffice if there is an unmet medical need and the trial data are convincing.<\/p>\n Can efficacy be conclusively proven in a single trial?<\/strong><\/p>\n Formally, efficacy is never conclusively proven, but statistically demonstrated with a defined probability of error \u2013 usually p less than 0.05. Demonstration must be achieved with a predefined primary endpoint in order to prevent data dredging. Exploratory analyses are not considered confirmatory proof of efficacy.<\/p>\n","protected":false},"excerpt":{"rendered":" Efficacy refers, in the context of clinical trials, to the demonstrated effectiveness of a medicinal product or medical device under controlled study conditions. It is the central authorisation criterion for new therapies and is systematically measured and statistically demonstrated in controlled clinical trials \u2013 typically in Phase II and Phase III. Efficacy is to be […]<\/p>\n","protected":false},"author":10,"featured_media":0,"parent":0,"template":"","meta":{"_acf_changed":false,"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"set","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"glossary-cat":[],"class_list":["post-6980","glossary","type-glossary","status-publish","hentry"],"acf":[],"related_terms":"","external_url":"","internal_reference_id":"","_links":{"self":[{"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/glossary\/6980","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/glossary"}],"about":[{"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/types\/glossary"}],"author":[{"embeddable":true,"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/users\/10"}],"version-history":[{"count":1,"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/glossary\/6980\/revisions"}],"predecessor-version":[{"id":6981,"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/glossary\/6980\/revisions\/6981"}],"wp:attachment":[{"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/media?parent=6980"}],"wp:term":[{"taxonomy":"glossary-cat","embeddable":true,"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/glossary-cat?post=6980"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}