Essays on Decision Analytic Modeling for Hypertension and Frailty

Abstract

This dissertation uses decision analytic modeling to evaluate two clinical conditions prevalent in the United States: hypertension and frailty. In the first chapter, I study the value of intensive systolic blood pressure (SBP) targets in settings with different levels of SBP measurement error. Clinical trials have found that intensive SBP targets (i.e., targeting a SBP mm Hg) are effective at reducing cardiovascular event rates for patients with high cardiovascular disease risk. However, major clinical guidelines recommend higher targets of mm Hg and mm Hg. This is in large part due to concerns that SBP measurement error in routine practice combined with an intensive target would lead to overtreatment. To evaluate the value of intensive targets in routine practice, I developed a disease simulation model of hypertension that simulates different levels of SBP measurement error. I find that an intensive target would be cost-effective in settings with average or better levels of error. However, there is greater uncertainty with high levels of error, and a mm Hg target may be cost-effective. This work suggests that recommendations for SBP targets for patients with high cardiovascular risk should consider SBP measurement accuracy and that an intensive target may be cost-effective in many clinical settings. In the second chapter, I evaluate methods frequently used in disease simulation models to simulate the effect of SBP changes. Trials of SBP-lowering interventions frequently use SBP change as the primary outcome. As a result, cost-effectiveness analyses of these interventions must make assumptions about how SBP changes will affect long-term health outcomes, such as cardiovascular events and medication-related serious adverse events. In the first part of this chapter, I evaluate commonly used methods for projecting cardiovascular event rates based on SBP change. In the second part, I estimate rates of intervention-related serious adverse events as a function of SBP and standardized antihypertensive doses using an instrumental variables analysis. Both parts of this chapter can be used to inform and strengthen the validity of future economic evaluations of SBP-lowering interventions. In the third chapter, I study the health and financial burden of frailty and fall-related injuries among people with HIV. People with HIV experience age-related comorbidities, such as frailty and falls, at higher rates than people of the same age without HIV. In this work, I developed a disease simulation model of frailty and fall-related injuries among people with HIV, and I use this model to estimate the life years lost, quality-adjusted life-years (QALYs) lost, and costs attributable to frailty and falls. I find that pre-frailty and frailty are associated with 2.7 million life-years lost, 2.4 million QALYs lost, and $21.5 billion in spending. Fall-related injuries and fractures are associated with 261,300 life-years lost, 209,400 QALYs lost, and $6.9 billion in spending. Describing these costs and health losses may motivate future work to inform decisions about how to provide high value care to prevent and treat frailty and fall-related injuries.