In this cluster, apart from defining ‘Effectiveness’, we also give the definitions for ‘Effective care’ and ‘Efficacy’.


The effectiveness of an intervention, from single treatments through to services including the professionals within them, is the degree to which the desired outcomes are achieved in clinical practice.

Source: Gray M (2009) Evidence-Based Healthcare and Public Health. How to make decisions about health services and public health. 3rd edition. Churchill Livingstone Elsevier. Page 193.

Two examples of the term in use:

In summary, the evidence suggests that home care is a service that is highly valued by many carers. In addition, the more rigorous research evidence also suggests that home care contributes to caregiver welfare, although it may not be the most effective form of intervention for this purpose.

Pickard L (2004) The effectiveness and cost-effectiveness for support and services to informal carers of older people. A review of the literature prepared for the Audit Commission. Personal Social Services Research Unit, London School of Economics.

The effectiveness and cost effectiveness of population based dietary approaches to prevention of cardiovascular disease in the UK are less clear.

Barton P, Andronis L, Briggs A et al (2011) Effectiveness and cost-effectiveness of cardiovascular disease prevention in whole populations: modelling study. BMJ 2011; 343 doi: (Published 28 July 2011) Cite this as: BMJ 2011;343:d4044

Effective care

Effective care comprises services whose use is supported by well-articulated medical theory and strong evidence for efficacy, as determined by clinical trials or valid cohort studies. The category is further restricted to interventions that virtually all patients should want as part of the contract they make with their health care systems.

Source: Wennberg JE, Fisher ES, Skinner JS (2002) Geography And The Debate Over Medicare Reform. Health Affairs Web Exclusive.

Example of the term in use:

Effective care … includes evidence-based services (such as haemoglobin A1c testing for diabetic patients) where variations will reflect failure to deliver needed care.

Appleby J, Raleigh V, Frosini F et al (2011) Variations in health care. The good, the bad and the inexplicable. The King’s Fund. Page 5.


The magnitude of the benefit demonstrated in the research setting is sometimes referred to as the efficacy of an intervention.

Source: Gray M with Bevan G, Cripps M, Jani A, Ricciardi W (2017) How To Get Better Value Healthcare. Third edition. Offox Press, Oxford. Page 23.

Example of the term in use:

BCG vaccine has been the subject of numerous efficacy trials and epidemiological studies conducted over several decades. These trials indicate that BCG has 60-80% protective efficacy against severe forms of tuberculosis in children, particularly meningitis, and its efficacy against pulmonary diseases varies geographically.

Roy A, Eisenhut M, Harris RJ et al (2014) Effect of BCG vaccination against Mycobacterium tuberculosis infection in children: systematic review and meta-analysis. BMJ 2014; 349 doi: (Published 05 August 2014) Cite this as: BMJ 2014;349:g4643