HSR&D Home » Research » RRP 08-250 – HSR&D Study
Using System Dynamics Tools to Integrate Evidence into VA Stroke Care
Hayden B Bosworth, PhD
Durham VA Medical Center, Durham, NC
Funding Period: October 2008 - March 2009
The prevalence, morbidity, impact, and cost of stroke make it a critical health problem in the United States and a major concern for the VA. In Fiscal Year (FY) 05, approximately 17,000 patients were treated by the VA for stroke, with an average total cost of treatment over $18,000/patient. Within the VA, there are major opportunities to reduce the burden of stroke through prevention, acute treatment, and rehabilitation. Because of its profound importance within the VA, stroke has been identified as one of the conditions for which a Quality Enhancement Research Initiative (QUERI) has been established. While the Stroke QUERI has identified evidence-based strategies to improve stroke care, the challenge of how best to further translate evidence into practice remains. In particular, key questions include: (1) How do we decide among evidence-based options? (2) How do we allocate limited resources to have the most substantial effect? (3) How do we mobilize expertise to maximize impact? (4) How do we tailor interventions to meet the specific needs of veteran populations?
The goal of this RRP is to use System Dynamics methodology to begin to map and simulate the stroke care system in the VA. The goal of investing in the development of this simulation model is to use it as a decision support tool to assist the Stroke QUERI in prioritizing its activities. The pilot model will be used to help the group identify the possible areas of focus that are most likely to have the biggest impact on key stroke outcomes in the VA enrollee population, including: disability adjusted life years, the number of strokes, the number of stroke-related deaths, and VA system costs.
This project uses System Dynamics simulation modeling to help key stakeholders of the Stroke QUERI establish strategic actionable priorities. We met with key system stakeholders represented on the Stroke QUERI Executive Committee to establish a shared conceptual framework of the continuum of stroke in the VA and to identify the key classes of interventions under consideration. The framework was transformed into a stock and flow simulation model in Vensim software (www.vensim.com) and simulates the population of veteran enrollees between 2008 and 2028, separating enrollees into mutually exclusive stocks based on whether or not they have experienced an event (TIA or stroke, with post-stroke enrollees separated by modified Rankin score) or are in a high or low risk group for having an event (high risk is defined as having one or more risk factor, including: smoking, diabetes, hypertension, high cholesterol or atrial fibrillation). The model was evaluated for a range of possible input values to consider which potential leverage points were most promising in terms of their potential to reduce stroke burden in terms of years of disability or death (disability adjusted life years, DALYs).
Key identified leverage points included: community awareness, first event (TIA, stroke) prevention, tPA use, recurrent event (TIA, stroke) prevention, office MD response to non-hospitalized TIA, and stroke rehabilitation. Preliminary results suggest that each leverage point except recurrent event prevention is cost-effective based on traditional criteria that anything costing less than $50,000/DALY is cost-effective. In terms of the impact on reduction in overall stroke burden, only first event prevention, rehabilitation, MD response to TIA and recurrent event prevention can independently be expected to generate an increase in DALYs of 100,000 in the next 20 years. Based on absolute shifts in practice, the smallest change would be needed in first event prevention (as measured by both percent of veterans reached with prevention efforts and the quality of prevention efforts that are received improving from 40 to 42%). That said, this class of interventions is not the most cost-effective, largely because of the scale at which efforts would need to be rolled out (more than 4.5 million veterans constitute the high-risk target population. More targeted efforts to reduce risk after veterans experience a TIA may prove much more cost-effective.
The model provides a framework for considering the potential impact of VA policy actions on the burden of stroke. This preliminary exercise reinforced the cost effectiveness of interventions aimed at primary prevention. Notably, while the needed improvement in primary prevention is apparently small, the needed effort likely represents substantial overall effort given the size of the target population. Based on costs alone, enhancing MD response to TIA seems likely to affect the same increase in DALYs at a much lower cost, while preventing more strokes and stroke-attributable fatalities. Though community awareness and tPA are not independently capable of increasing DALYs by 100,000 over the next 20 years, they do seem to be cost saving.
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Keywords: Informatics, Stroke
MeSH Terms: none