Variation in care and outcome following myocardial infarctionBMJ 2015; 351 doi: https://doi.org/10.1136/bmj.h4133 (Published 07 August 2015) Cite this as: BMJ 2015;351:h4133
- Kumar Dharmarajan, assistant professor of medicine
- 1Section of Cardiovascular Medicine, Yale University School of Medicine, 1 Church Street, Suite 200, New Haven, CT 06510, USA
Research describing variation in hospital treatment and outcomes has improved care for patients with acute myocardial infarction. Studies, particularly from the United States, have shown significant differences in hospitals’ use of evidence based tests and treatments for acute myocardial infarction including aspirin, β blockers, and angiotensin converting enzyme inhibitors.1 In response, major US organizations developed a set of core process measures for treatments considered to be standard of care.2 Hospitals’ performance on these measures were publicly reported and used to guide reimbursement.3 Subsequently, research identified significant variation in hospitals’ outcomes for acute myocardial infarction, including rates of 30 day readmission and mortality.4 The federal government has used hospitals’ performance on these metrics to exact financial penalties on institutions with worse than expected 30 day outcomes.5
It is with this focus on quality of healthcare that Chung and colleagues in the linked paper (doi:10.1136/bmj.h3913) describe variation in guideline recommended treatments and outcomes for patients admitted with acute myocardial infarction in the United Kingdom and Sweden.6 The authors examined nationwide registry data from all hospitals providing care for acute myocardial infarction in both countries between 2004 and 2010. They found that variation in use of many guideline recommended treatments such as primary percutaneous intervention for ST elevation myocardial infarction and β blocker treatment for all infarction subtypes was higher in the United Kingdom than Sweden. They also found that variability in 30 day mortality was greater in UK hospitals after standardization for case mix. Approximately a quarter of variation in 30 day mortality across hospitals was explained by variation in use of guideline based care in both countries. Risk of death was higher in hospitals less likely to provide guideline concordant care.
These results reaffirm the primacy of outcomes measures over process measures for evaluating the care of patients with myocardial infarction in both the United Kingdom and Sweden. As with data from the United States,7 most of the variation in 30 day mortality cannot be explained by differences in guideline recommended care across hospitals. Although this does not diminish the importance of evidence based care,8 which may primarily improve long term outcomes, it does suggest that 30 day outcomes substantially relate to factors beyond the provision of a restricted number of disease specific treatments. These factors may include the values and goals of hospital employees, their manner of communication and coordination, and the overall culture of problem solving and learning within the institution.9 Outcomes may also relate to hospitals’ efforts to provide high quality transitional and post-acute care.10
The new findings also identify specific gaps in care that differ by country. UK hospitals in 2010, for example, exhibited great variation in the proportion of patients receiving revascularization after non-ST elevation myocardial infarction, with an interquartile range of 19.8-50.5%. No “gold standard” exists for the proportion of such patients that benefit from revascularization. However, such large differences in revascularization rates across the middle 50% of hospitals are highly unlikely to be explained by case mix differences alone, especially because patients at both intermediate and high risk with non-ST segment myocardial infarction are known to benefit from revascularization.11
Similarly, 2010 data from Sweden show significant variation across hospitals in statin use at discharge, with an interquartile range of 81.4-91.3%. As the benefits of statins in secondary prevention, including after myocardial infarction, are well established, little reason exists for one in five patients to miss this treatment. These data make clear that each year, many thousands of patients with myocardial infarction do not receive optimal care in both countries.
Ultimately, efforts to reduce variation in the United Kingdom, Sweden, and elsewhere will probably be more successful once its drivers are better understood. Many questions remain for future researchers to consider. For example, are hospitals without standardized protocols, checklists, and care pathways less likely to provide guideline based care? To what extent do patients’ preferences influence decisions about treatment? How does the competency of cardiologists performing invasive procedures at each hospital affect differences in 30 day outcomes? Does the quality of communication among hospital based providers, outpatient providers, and patients’ caregivers influence mortality after discharge? The drivers of variation are likely to be quite complex and diverse, with substantial differences by country and hospital.
Policy makers in both the United Kingdom and Sweden could require that all hospitals submit complete data for all admissions with acute myocardial infarction to national registries.12 13 Both could also make summary data on guideline based treatments and outcomes easily available to patients and researchers interested in comparing individual hospitals, as is done by Hospital Compare (www.medicare.gov/hospitalcompare/search.html) in the United States. Finally, both countries could consider linking hospital reimbursement to quality.
Although voluntary, multi-institutional, and professionally governed collaborations in both countries have stimulated large improvements in care for patients with myocardial infarction,12 13 Chung and colleagues show that important disparities remain. Both the United Kingdom and Sweden are well positioned to measure and reduce these differences, as they can build hospital quality measures by linking data from pre-existing clinical registries with patients’ longitudinal health outcomes. With planning, data collected for these registries can permit accurate adjustment for case mix differences among hospitals.
Patients having a heart attack do not have the time to shop around for high quality care. Differences across hospitals in guideline based treatment and outcomes are therefore particularly concerning. The quantification of this variation in the United Kingdom and Sweden is an essential step towards reducing these disparities in both countries.
Cite this as: BMJ 2015;351:h4133
Funding: I am supported by grant K23AG048331 from the National Institute on Aging and American Federation for Aging Research through the Paul B Beeson Career Development Award Program. The content is solely the responsibility of the author and does not necessarily represent the official views of the National Institutes of Health or the American Federation for Aging Research.
Competing interests: I have read and understood the BMJ policy on declaration of interests and declare the following interests: I work under contract with the Centers for Medicare and Medicaid Services in the United States to develop and maintain performance measures, and I serve on the scientific advisory board of Clover Health.
Provenance: Commissioned; not externally peer reviewed.
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