In examining how to improve patient outcomes we turn to population medicine to develop treatment strategies. A powerful analysis of these efforts should include a Treatment Cascade. The cascade follows a cohort with the target condition to be treated. In the analogy they all start out in kayaks at the top of the cascade and begin to shoot the rapids. Each drop-off in the cascade is defined by significant events that reduces the number of successful paddlers that will make it to the end, the bottom of the cascade – the desired medical outcome. The number of kayakers who begin shooting the rapids define the denominator – the total eligible population. The number remaining at the end of each drop off, the numerators at each point along the cascade. With the numerator at each point and the original denominator a rate of success and loss can be determined. An examination of the events at each cascade drop off can lead to a strategy to reduce the loss at the most effective point(s) along the way and increase the rate of success in the end.
Here is a common example of a treatment cascade in the medical literature for HIV infection in the US as of 2012. Of the people in the US infected with HIV is estimated that 82% are aware of their infection – they have been tested. The other 18% are unaware. This 18% is the first cascade loss. Notable, is the very large drop off seen between individuals diagnosed with HIV, linked to care but not retained in care. An additional 29% of the kayakers are lost at this cascade. So even with the highly effective treatment for HIV infection that is currently available at the end of the cascade of events only 25% of rafters have their HIV suppressed.
Where the 18% at the top of the cascade that do not know if their infection may be an easy target (strategies for more testing), that group of rafters are subject to all of the downstream events that keep them from completing the run. Unless the reduction in the drop off is large the end result may be unimpressive. Targeting the 29% that are lost to follow up care may have more people complete the run if you can arrive at a successful strategy. They have already negotiated the upper cataracts of the cascade without being lost and are left shoot the lower rapids to completion. Remember, targeting this hydraulic hole will not restore the 18% lost at the first fall.
Every medical condition or activity involving a series of sequential actions may be plotted on a treatment cascade. For Partnership HealthPlan medical offices participating in the Quality Improvement Program most all of its population based elements can be plotted on a cascade. By analyzing the way a cascade falls changes could be implemented to increase the number of individuals who successfully shoot the rapids to smooth water.
Marshall Kubota, M.D.