Case Volume and Hospital Compliance With Evidence-based Processes of Care
Case Volume and Hospital Compliance With Evidence-based Processes of Care
Background: For many complex cardiovascular procedures the well-established link between volume and outcome has rested on the underlying assumption that experience leads to more reliable implementation of the processes of care which have been associated with better clinical outcomes. This study tested that assumption by examining the relationship between cardiovascular case volumes and the implementation of twelve basic evidence-based processes of cardiovascular care.
Method and Results: Observational analysis of over 3000 US hospitals submitting cardiovascular performance indicator data to The Joint Commission on during 2005. Hospitals were grouped together based upon their annual case volumes and indicator rates were calculated for twelve standardized indicators of evidence-based processes of cardiovascular care (eight of which assessed evidenced-based processes for patients with acute myocardial infarction and four of which evaluated evidenced-based processes for heart failure patients). As case volume increased so did indicator rates, up to a statistical cut-point that was unique to each indicator (ranging from 12 to 287 annual cases). t-Test analyses and generalized linear mixed effects logistic regression were used to compare the performance of hospitals with case volumes above or below the statistical cut-point. Hospitals with case volumes that were above the cut-point had indicator rates that were, on an average, 10 percentage points higher than hospitals with case volumes below the cut-point (P < 0.05).
Conclusion: Hospitals treating fewer cardiovascular cases were significantly less likely to apply evidence-based processes of care than hospitals with larger case volumes, but only up to a statistically identifiable cut-point unique to each indicator.
It has been well established that for many complex medical and surgical procedures, patients receiving services in high-volume hospitals have reduced risks of mortality and complications compared to patients receiving these same services in lower-volume hospitals. While this relationship between volume and outcome has been consistently documented in the medical literature, the underlying causal factors have been less well understood. Despite this relative lack of understanding, many health care purchasers, led by the Leapfrog Group, have sought to take advantage of the presumed correlation between volume and outcome by initiating 'evidence-based referral' processes. Through evidence-based referral, patients are directed towards high-volume centers (and away from low-volume centers) using case volume thresholds as an indicator of quality for certain cardiovascular procedures. Recent analyses, however, suggest that this approach may be of questionable benefit, is difficult to implement, and comes with its own potential risks to patients.
This should not be surprising. It has been observed that 'volume' is not an indicator of quality, but rather a structural characteristic that has been associated with quality. Surgical volume, for example, is generally assumed to reflect institutional and surgeon experience with a procedure, which is further assumed to be related to better surgical technique and more reliable implementation of the processes of care which have been associated with superior clinical outcomes. While the relationship between certain processes of care and outcomes has been well established through randomized controlled trials and qualitative research, the assumed relationship between hospital volume and the reliable implementation of specific evidence-based processes of care has never been confirmed. Building upon the well established link between volume and outcome for cardiovascular procedures, we hypothesized that hospitals with higher cardiovascular case volumes (i.e. greater experience) would also be more likely to implement evidence-based cardiovascular processes of care.
Abstract and Introduction
Abstract
Background: For many complex cardiovascular procedures the well-established link between volume and outcome has rested on the underlying assumption that experience leads to more reliable implementation of the processes of care which have been associated with better clinical outcomes. This study tested that assumption by examining the relationship between cardiovascular case volumes and the implementation of twelve basic evidence-based processes of cardiovascular care.
Method and Results: Observational analysis of over 3000 US hospitals submitting cardiovascular performance indicator data to The Joint Commission on during 2005. Hospitals were grouped together based upon their annual case volumes and indicator rates were calculated for twelve standardized indicators of evidence-based processes of cardiovascular care (eight of which assessed evidenced-based processes for patients with acute myocardial infarction and four of which evaluated evidenced-based processes for heart failure patients). As case volume increased so did indicator rates, up to a statistical cut-point that was unique to each indicator (ranging from 12 to 287 annual cases). t-Test analyses and generalized linear mixed effects logistic regression were used to compare the performance of hospitals with case volumes above or below the statistical cut-point. Hospitals with case volumes that were above the cut-point had indicator rates that were, on an average, 10 percentage points higher than hospitals with case volumes below the cut-point (P < 0.05).
Conclusion: Hospitals treating fewer cardiovascular cases were significantly less likely to apply evidence-based processes of care than hospitals with larger case volumes, but only up to a statistically identifiable cut-point unique to each indicator.
Introduction
It has been well established that for many complex medical and surgical procedures, patients receiving services in high-volume hospitals have reduced risks of mortality and complications compared to patients receiving these same services in lower-volume hospitals. While this relationship between volume and outcome has been consistently documented in the medical literature, the underlying causal factors have been less well understood. Despite this relative lack of understanding, many health care purchasers, led by the Leapfrog Group, have sought to take advantage of the presumed correlation between volume and outcome by initiating 'evidence-based referral' processes. Through evidence-based referral, patients are directed towards high-volume centers (and away from low-volume centers) using case volume thresholds as an indicator of quality for certain cardiovascular procedures. Recent analyses, however, suggest that this approach may be of questionable benefit, is difficult to implement, and comes with its own potential risks to patients.
This should not be surprising. It has been observed that 'volume' is not an indicator of quality, but rather a structural characteristic that has been associated with quality. Surgical volume, for example, is generally assumed to reflect institutional and surgeon experience with a procedure, which is further assumed to be related to better surgical technique and more reliable implementation of the processes of care which have been associated with superior clinical outcomes. While the relationship between certain processes of care and outcomes has been well established through randomized controlled trials and qualitative research, the assumed relationship between hospital volume and the reliable implementation of specific evidence-based processes of care has never been confirmed. Building upon the well established link between volume and outcome for cardiovascular procedures, we hypothesized that hospitals with higher cardiovascular case volumes (i.e. greater experience) would also be more likely to implement evidence-based cardiovascular processes of care.
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