A new measure for assessing the cost-effectiveness of health care interventions: the SF-6D
The decision about whether to fund new health care interventions is increasingly being informed by evidence of costeffectiveness in terms of the cost per Quality Adjusted Life Years (QALY). The SF6D health index has become widely used internationally for calculating QALYs from patient reported health outcomes collected in clinical trials and other surveys. It contributes to health system efficiency and is used to facilitate decisions about the most efficient use of limited health care resources.
The benefits of SF-6D
The SF-6D was derived from the SF36 (www.sf36.org), a widely used patient reported measure that assesses health across 8 dimensions. The SF36 does not enable trade-offs between them (e.g. pain vs. physical functioning), or between quality and length of life. These are needed to calculate QALYs and assess cost-effectiveness. The SF-6D index was developed in order to overcome these limitations.
These values for comparison are provided by the SF-6D’s single index, making it possible to work out the cost per QALY. Data is collected during clinical trials and other health studies. People report how they feel their health is in areas like mobility, self-care, impact on work and social activities, pain, energy, depression and anxiety. Analysis using the SF-6D software provides an important input into the evaluation of affordability that informs decisions about whether an intervention should be made available in a health system or not.
The main research was published in 2002 and since then the SF-6D has become widely used around the world. The SF-6D has a number of advantages over the previously used main health valuation measure the EQ-5D:
- it has a richer descriptive system (with 18,000 states as opposed to only 243 for the EQ-5D)
- it is more sensitive to health changes particularly for milder states and
- it covers a broader range of health dimensions by including role limitations, social functioning and vitality.
The SF-36 is often used in clinical studies and so this algorithm enables QALYs to be estimated without the need for additional data collection.
Impact on international public policy and services (HTA regulatory authorities)
An important impact of the SF-6D has been its use by HTA regulatory bodies around the world for assessing the costeffectiveness of health technologies. The SF-6D is recommended for use by Health Technology Assessment (HTA) agencies in Ireland and China; it is explicitly named as an accepted measure in Australia, Belgium, Canada, Norway, South Korea and Thailand; it also meets the specific guideline requirements of HTA agencies in 21 other countries whose guidelines are available via the ISPOR website and thus can be used for health care decision making in those countries.
It is also featured in the European Network for Health Technology Assessment (eunethat) Guideline on health-related quality of life and utility measures.
The SF-6D has been used in decision making in the UK by the National Institute for Health and Care Excellence. It has been used as the main health utility measure in important assessments such as pharmacological treatments for Alzheimer’s (NICETA217), gout (NICESTA118301), low platelet count (NICESTA088101) and peripheral arterial disease (NICETA223), and has been used alongside other measures in many other appraisals.
The main commercial users of the SF-6D have been pharmaceutical companies and consultancy companies working on their behalf who wish to examine the cost-effectiveness of new drugs and make submissions to regulatory authorities.
It is available through the Research and Innovation Service at the University of Sheffield, a company specialising in marketing IP owned by the University. The selling of the SF-6D has also been subcontracted to Quality Metric, a US based company specialising in measuring health outcomes who also distribute other SF products including SF-36 and SF-12.
Since 2008, they have together sold over 460 licenses to pharmaceutical and consultancy companies including Novartis, Roche, Pfizer, Novo Nordisk, Astellas, Merck, Sanofi and BMS. Other important commercial users have been health care insurers and providers in the USA. The companies benefit because an accepted generic health measure administered in their clinical trial (the SF-36 or SF-12) can be directly, and easily, translated into a preference based measure that can be used in economic evaluation. The SF-6D enables them to estimate the health-related quality of life benefits of their technology in terms of QALYs, which is a requirement for a submission to regulatory bodies around the world.
How do you access the SF-6D?
Access to the SF-6D is through either a license for commercial applications from the University’s commercialisation partner in the UK, Fusion IP, or from Quality Metric in the US who supply the software for a charge. Non-commercial applications covering all public sector and charitable applications are free of charge and copies of the software can be obtained through ScHARR; 521 non-commercial licenses have been distributed since 2008.
We are developing similar QALY products for specific populations and conditions. These include a measure for children (CHU-9D) and measures for cancer, asthma, overactive bladder and mental health.
The SF-6D is an easy to use single index measure of benefit that you can then compare to the cost. There is a need for alternative methods to standard tools and people are often looking for something else.
Professor John Brazier
For example, following this research we are currently underway with developing a new outcome measure for people who are using mental health services - Recovering Quality of Life (ReQoL).
More information about ReQoL is available here.
Research Excellence Framework 2014, ScHARR’s impact case studies
For further information about the study:
Brazier J, Roberts J, Deverill M (2002) The Estimation of a Preference-Based Measure of Health from the SF-36 Journal of Health Economics, 21(2) 271292. doi: 10.1016/S0167-6296(01)001308  [Awarded the 2002 International Society for Quality of Life Prize for "Outstanding contribution to the study of health related quality of life’’. Andrew Oswald (2009), in his Warwick Economics Research Paper (No.887) “World-leading research and its measurement”, notes this paper as among the top most cited economics papers in the world.