The Global Outcomes Score

Achieving a high quality health care system is the holy grail in medicine these days. A novel way of viewing quality requires analysis of the reduction in risk of severe adverse events expected from health care interventions.

We all can agree that quality in health care should be measured and promoted. Up for debate, is the best way to accomplish this complex task. Until recently, methods of quality measurement have largely relied on performance measures based on processes or treatment goals.

while possibly neglecting others. As a response to current measures, researchers have attempted to create a “Global Outcomes Score” which is designed to “represent the extent to which current levels of care are reducing the risk of bad outcomes in a population.”

The Global Outcomes Score for heart attack would be defined as follows: there is a rate of bad outcomes (heart attack) in three scenarios – no care, current care, and target care. If there were 500 heart attacks per 100,000 population under no care, 300/100,000 under current care, and an expected 100/100,000 under target care, the Global Outcomes Score would be calculated as the current risk reduction divided by the target risk reduction (i.e. (500-300)/(500-100) = 50 percent). In different terms, current care is preventing half of the heart attacks that could be prevented under ideal situations. Stringing together various outcomes for a multitude of conditions, and  incorporating quality-adjusted life years into the equation, a composite score can be formulated to compare overall quality for clinicians, patient populations, and even the nation as a whole.

To validate the Global Outcomes Score, the researchers applied it to a study population from the Atherosclerosis Risk in Communities study conducted from 1987 to 1998. They looked at treatment for high blood pressure (based on JNC7 guidelines) and high cholesterol (based on ATP III guidelines). Additionally, the researchers looked at adverse events defined as the number of strokes and heart attacks during the five year study period.

At the initiation of the study,  the “no care” cohort would have had 386 heart attacks and strokes over the 5 years study period based on mathematical modeling. With “target care”  (100 percent guideline adherence), the number of heart attacks and strokes would have been reduced to 281 events. The actual number of events (i.e. current care) was 344. Thus the Global Outcomes Score was 40 percent ((386-344)/(386-281)). Interpretation of the score means that 40 percent of adverse cardiovascular events were prevented at the initiation of the study compared to immediate adherence to the JNC7 and ATPIII guidelines.

The researchers proposed the Global Outcomes Score as a way to convert traditional process measures and treatment outcome measures into a measurement of risk for adverse clinical events. Instead of determining the percentage of patients a clinician or health plan has been successful in lowering LDL cholesterol or systolic blood pressure, the Global Outcomes Score estimates the relative risk reduction of adverse events that those patients might enjoy.

The Global Outcomes Score also converts dichotomous outcomes that likely have limited clinical significance into a continuous numerical score that places critical inspection on the marginal benefits of treatments. For instance, a traditional performance measure of obtaining systolic  blood pressure <140 would be largely impacted if an individual patient’s blood pressure went from 142 to 138. With the Global Outcomes Score, such marginal benefits would less likely reduce adverse event risk and therefore not influence the score. However, (as well as clinical guidelines) would incentivize physicians to intensify therapy at a significant monetary cost to the patient and society with questionable clinical benefit. The Global Outcomes Score would compliment current techniques in quality measurement.

Commentary

Achieving the maximum quality in health care represents the latest search for the holy grail in medicine. Current techniques – which include measuring performance on processes and intermediate outcomes (blood pressure control, cholesterol levels, or HbA1C) -focus the efforts of clinicians on obtaining specific numerical values without concern for disease prevention. Yet, many of these intermediate outcomes are related to the prevention of severe diseases such as heart attack and stroke. Unfortunately, the current data on pay-for-performance has yielded mixed results.

The Global Outcomes Score represents a novel way of classifying quality measurement with a focus on preventing the long term sequelae of disease. The scores obtained can be used to form a rational comparison for composite quality in the primary care setting or for population health. The score relies heavily on evidence-based medicine to conclude risk reduction of specific interventions and would be largely inappropriate in the absence of such prospective data.

Policy makers will continue their search for the holy grail but must keep physicians on the expedition.

Eddy, DM, et al. “The ‘global outcomes score’: a quality measure, based on health outcomes, that compares current care to a target level of care.” Health Affairs. 2012; 31 (11): 2441-2450.

by

Cedric Dark, MD, MPH