Originally posted 11/18/2011
Today I’m starting a new series on population health measurement, motivated by the idea that “you can’t manage what you can’t measure.” While there is no shortage of measures and rankings, there’s actually little consensus on what metrics are best suited to assess progress in population health improvement. Last week I urged Triple Aim architects to clarify how population health is defined in their model, but they’re not the only ones with definitional issues.
Metrics can assess a single item, such as infant mortality rates, or be bundled into groups to create summary measures. America’s Health Rankings (AHR) and the County Health Rankings (CHR) both use summary measures to annually rank, respectively, the health of states and counties within states. AHR has been ranking the health of states since 1990 and released its most recent rankings in December 2010. This important national resource informed work by the University of Wisconsin Population Health Institute to rank the health of Wisconsin counties beginning in 2003 and, for the first time in 2010, counties in every state. Dr. Pat Remington and I are proud to serve on AHR’s Scientific Advisory Committee.
The AHR and CHR share a common goal of population health improvement and both projects take pride in their deliberate, systematic, and transparent approaches. Both projects create summary measures for health outcomes (using metrics such as premature death, quality of life, and poor birth outcomes) and health factors or determinants (using metrics that capture health behaviors, clinical care, and social/economic/physical/policy environments). However, while CHR uses the health outcomes summary measure to identify the healthiest counties, AHR creates its overall rankings based on both outcomes and determinants.
So what does this look like in action? From 2009 to 2010, Wisconsin dropped from 11 to 18 in AHR overall rankings. But, a look at separate outcomes and determinants rankings over the same time period tells a slightly different story. Our determinants ranking is identical to the overall ranking (we dropped from 11 to 18). However, our health outcomes ranking improved slightly, from 16 to 15.
Why is this important? In general, we think of outcomes as a reflection of our current health and determinants as a predictor of our future health. The two summary measures often move in the same direction, but not always. When we launched the national CHR in 2010 with support from the Robert Wood Johnson Foundation, some wanted to know why our rankings didn’t have an overall score like AHR. The answer has to do with how the results are communicated and their implications for action. We felt strongly in the value of the two different measures to communicate different but equally important concepts about population health, particularly for policy makers.
Places with determinants better than outcomes are on the right track toward health improvement. But, for those such as Wisconsin with declining determinants, unless we act to reverse the trend, there is cause for concern about potential declines in health outcomes. It is the outcomes we are trying to improve, and the determinants that will get us there.