Timing of testing and treatment for asymptomatic diseases

Optimal cholesterol treatment plans and genetic testing strategies for cardiovascular diseases

Atherosclerotic cardiovascular disease (ASCVD) is among the leading causes of death in the US. Although research has shown that ASCVD has genetic elements, the understanding of how genetic testing influences its prevention and treatment has been limited. To this end, we model the health trajectory of patients stochastically and determine treatment and testing decisions simultaneously. Since the cholesterol level of patients is one controllable risk factor for ASCVD events, we model cholesterol treatment plans as Markov decision processes. We determine whether and when patients should receive a genetic test using value of information analysis. By simulating the health trajectory of over 64 million adult patients, we find that 6.73 million patients undergo genetic testing. The optimal treatment plans informed with clinical and genetic information save 5,487 more quality-adjusted life-years while costing $1.18 billion less than the optimal treatment plans informed with clinical information only. As precision medicine becomes increasingly important, understanding the impact of genetic information becomes essential.

Population-level intervention and information collection in dynamic healthcare policy

We develop a general framework for optimal health policy design in a dynamic setting. We consider a hypothetical medical intervention for a cohort of patients where one parameter varies across cohorts with imperfectly observable linear dynamics. We seek to identify the optimal time to change the current health intervention policy and the optimal time to collect decision-relevant information. We formulate this problem as a discrete-time, infinite-horizon Markov decision process and we establish structural properties in terms of first and second-order monotonicity. We demonstrate that it is generally optimal to delay information acquisition until an effect on decisions is sufficiently likely. We apply this framework to the evaluation of hepatitis C virus (HCV) screening in the general population determining which birth cohorts to screen for HCV and when to collect information about HCV prevalence.

Pre-clinical Crohn's disease: diagnosis, treatment and six year follow-up

Diagnosis of Crohn's disease is usually made at a symptomatic stage. However diagnosis at a pre-clinical stage might provide valuable information on etiology/pathogenesis and allow early intervention to alter its natural history. We describe here the case of a 27 year old woman who was diagnosed with Crohn's disease at a completely asymptomatic stage and followed up for more than six years. She was part of an ongoing screening study in first degree relatives of Crohn's disease patients. At diagnosis, colonoscopy showed modest inflammation and few superficial ulcerations and erosions in the ileo-cecal valve and the terminal ileum. Fecal calprotectin was only modestly elevated. Intestinal permeability was also increased. During follow-up and while still asymptomatic the patient was sequentially treated with therapeutic doses of 5-ASA, budesonide, azathioprine and infliximab in an attempt to stop disease progression. Only infliximab appeared capable of inducing profound mucosal healing-however the disease recurred several months after the medication was ceased. Over time, quantification by immunohistochemistry of a number of cell types and cytokines revealed a positive correlation between CD4-CD25-FOXP3 (Treg) cell number and inflammation, a finding potentially consistent with tissue resistance to Tregs' activity.