In its latest Croakey update, the Primary Health Care Research and Information Service (better known as PHC RIS) highlights concerns about over-reliance on the use of surrogate markers in health research, practice and policy.
Diabetes care reveals the pitfalls of surrogate markers
Christina Hagger writes:
‘What works’ in evidence-influenced health care is being overshadowed by ‘What can be measured’.
In a recent article in the BMJ (extract free, pay for full access), Yudkin and colleagues argue that the quality of medical practice is being infiltrated by an over reliance on surrogates being used as substitute predictors for clinically meaningful endpoints.
The US Institute of Medicine defines surrogates as biomarkers (such as glucose, blood pressure or lipids) that are based on epidemiologic or other scientific evidence and used to predict clinical benefit or harm.
Using diabetes as an example, the authors observe that much of the evidence for clinical interventions is based on results drawn from such surrogate markers rather than outcomes central to the patient experience such as vision loss, amputation or quality of life.
Furthermore, as the surrogate markers are generally more responsive to interventions than such ‘hard’ end points as renal failure, the authors suggest that many of the widely accepted strategies for diabetes may be based on artificially inflated expectations.
Adding to these concerns are their observations that surrogate outcomes, despite their severe limitations as perfect surrogates for patient centred outcomes, are assuming their own mantles of importance as measurable reference points for both clinical research and evaluation of health care.
The findings of such research and evaluations are used to shape policy and practice as well as influence funding.
The result is that patients with diabetes may be treated to achieve target levels of surrogates. While the authors concede such actions are usually made in a patient’s best interests, these decisions carry no information to which patients can relate, thus withdrawing opportunities for personal engagement in their own treatment plans. Such surrogate-centric rather than patient focused strategies are counter-productive to efforts to develop patient centred medicine.
The reliance on surrogate markers sees health care shift back to a disease management approach and away from people, their quality of life and their narratives.
A surrogate is a detached marker, it does not bleed, feel fear or pain. It does not communicate a story to the patient to engage them in their health care.
Yes, evidence-influenced health care is our goal, and we need to know how to measure it but the current over-reliance on surrogates is derailing our successes by diverting our attention to measure, fund and practise only that which can be readily measured and drawing our eye away from the living complexities that are our patients.
What are we really measuring, funding and doing?
• Christina Hagger is a Research Fellow, Primary Health Care Research & Information Service (PHC RIS)
The BMJ article cited is not freely available but Croakey is happy to provide a copy to interested readers. Leave your details below or send an email.
Yudkin JS, Lipska KJ, Montori VM, The idolatry of the surrogate. BMJ 2011;343:d7995. This article features in the 19 January 2012 edition of PHC RIS eBulletin, available at http://www.phcris.org.au/publications/ebulletin/index.php.
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Previous Croakey posts from the PHC RIS