MA. Published online April 15, 2019. doi:10.1001/jama.2019.4310
This weeks blog is brought to you by: Professor Sir Muir Gray, Founding Director
“The rationale for using HbA1c level as a surrogate for diabetes outcomes is predicated on the assumption of its direct correlation with outcomes that patients ultimately value, including clinical microvascular disease (eg, ESKD and need for dialysis, blindness, neuropathic pain, amputation), macrovascular disease (eg, myocardial infarction, stroke, painful neuropathy), quality of life, and death. Yet, the strength of this relationship has been called into question. Meta-analyses revealed a null association between intensive glycemic control and these patient-important outcomes, with the sole exception of a 10% to 15% relative risk reduction of nonfatal myocardial infarction……
Although potentially more challenging to measure or difficult to change, other measures of the quality of diabetes care may better represent the outcomes that are truly meaningful to people living with diabetes, including immediate symptoms of hypoglycemia or hyperglycemia, burden of treatment, to quality of life, and long-term sequelae of inadequately controlled diabetes…..
To improve the quality and value of diabetes care, it will be necessary for patients and all those involved in their care to focus on what truly matters to the people living with diabetes—improving their lives, not their laboratory numbers.”
3VH – Implications for value
Our Bottom Line – “Surrogate, proxy or process measures are necessary for assessing progress in the management of long term conditions, but if you’re interested in higher value healthcare for populations (in other words improving outcomes that matter for all people we serve from the resources available), you must be mindful that proxy measures are not the same as outcomes that matter”.
The clinical outcome of care for a long term condition , reduction in mortality or in the rate of complication may take years to become apparent so intermediate measures of outcome are necessary. However these measures are surrogates and it is essential to assess how well they relate to the real clinical outcomes and as this paper shows HbA1C may be better than random blood glucose measurements but is not perfect.
Of even greater importance is the fact that focusing on the biochemical results may distract attention from the problem that is bothering the person who is affected most so there is always a need to complement the biochemical with the personal. In addition unthinking adherence to the pursuit of the perfect surrogate outcome may also result in significant waste not only of health cervices resources but also patient time, adding to what the team in which Rozalina McCoy works, has termed ‘the burden of treatment.
Here is what another of their papers concludes
“In this US cohort of adults with stable and controlled type 2 diabetes, more than 60% received too many HbA1c tests, a practice associated with potential overtreatment with hypoglycemic drugs. Excessive testing contributes to the growing problem of waste in healthcare and increased patient burden in diabetes management.” (1)
This is the US of course but we cannot assume the results would be significantly different in the UK and criticism of the overuse of HbA1C has also been published from the UK with the article also having a telling title, asking explicitly “whose agenda?” (2)
1. HbA1c overtesting and overtreatment among US adults with Controlled type 2 diabetes, 2001-13: observational population based study Rozalina G McCoy R.G. et al (2015)
Cite this as: BMJ 2015;351:h6138 doi: 10.1136/bmj.h6138 Accepted: 30 October 2015
2. Judkin J.S. et al (2011)Intensified glucose control in type 2 diabetes – whose agenda Lancet 377; 1220-1222