INFORMING ADVANCE DIRECTIVES BY EXPLICITLY SIMULATING CARE TRAJECTORIES

Advance directives describe the choices patients would make in the event of critical illness in order to facilitate surrogate decision making. However, these directives are often under-informed due to a lack of disease-specific prognostic information, including outcomes beyond in-hospital survival. A decision model that explicitly simulates probable care trajectories with alternate treatments may inform these decisions.

Purpose: To inform advance directive decisions for patients with severe COPD by comparing probable care trajectories

Methods: We designed a Markov model of patients with severe COPD hospitalized for acute respiratory failure, to estimate the probable trajectories resulting from two alternative advance directives, Do Not Intubate (DNI, no invasive mechanical ventilation) vs. Full Code (all treatments permitted, including invasive mechanical ventilation). We included 5 Markov states: hospitalized with acute respiratory failure; living in the community; living in long-term care extended care facilities (long-term ECF); living in a short term ECF and dead. Outcome measures were 1-year survival, place of discharge, number of re-hospitalizations and a proxy for place of death. Variable estimates were based on published data or expert opinion. Homogeneous data (Q-statistic of >0.10, I-statistic of <25% and p-value <0.05, with no significant outliers on Forest plot) were pooled using Dersimonian and Laird random effects model. One-way and multi-way probabilistic sensitivity analyses were performed to test the model’s robustness and to identify influential variables.

Results: Patients endorsing the Full Code directive had marginally increased 1-year survival (Full Code vs. DNI, 46% vs. 43%). However, Full Code patients were more likely to be residing in a long-term ECF (Full Code vs. DNI, 15% vs. 4%) and to be re-hospitalized (DNI vs. Full Code, 48% vs. 39%). Full Code patients were also more likely to die while living in a long-term ECF (Full Code vs. DNI, 14% vs. 1%). Trajectories were sensitive to the probability of complications of invasive mechanical ventilation and the probability of failing non-invasive mechanical ventilation.

Conclusions: Choosing a Full Code directive may result in a tradeoff between survival versus increased likelihood of recurrent hospitalizations and institutionalization. Making these alternate care trajectories explicit using modeling may better inform advance directive choices for patients with severe COPD.