Proportional-assist ventilation with load-adjustable gain factors for mechanical ventilation: a cost-utility analysis

Abstract

Background: Mechanical ventilation is an important component of patient critical care, but it adds expense to an already high-cost setting. This study evaluates the cost-utility of 2 modes of ventilation: proportional-assist ventilation with load-adjustable gain factors (PAV+ mode) versus pressure-support ventilation (PSV).

Methods: We adapted a published Markov model to the Canadian hospital-payer perspective with a 1-year time horizon. The patient population modelled includes all patients receiving invasive mechanical ventilation who have completed the acute phase of ventilatory support and have entered the recovery phase. Clinical and cost inputs were informed by a structured literature review, with the comparative effectiveness of PAV+ mode estimated via pragmatic meta-analysis. Primary outcomes of interest were costs, quality-adjusted life years (QALYs) and the (incremental) cost per QALY for patients receiving mechanical ventilation. Results were reported in 2017 Canadian dollars. We conducted probabilistic and scenario analyses to assess model uncertainty.

Results: Over 1 year, PSV had costs of $50 951 and accrued 0.25 QALYs. Use of PAV+ mode was associated with care costs of $43 309 and 0.29 QALYs. Compared to PSV, PAV+ mode was considered likely to be cost-effective, having lower costs (-$7642) and increased QALYs (+0.04) after 1 year. In cost-effectiveness acceptability analysis, 100% of simulations would be cost-effective at a willingness-to-pay threshold of $50 000 per QALY gained.

Interpretation: Use of PAV+ mode is expected to benefit patient care in the intensive care unit (ICU) and be a cost-effective alternative to PSV in the Canadian setting. Canadian hospital payers may therefore consider how best to optimally deliver mechanical ventilation in the ICU as they expand ICU capacity.

Figure 1:

Structure of adapted Markov cohort cost-utility model. The clinical stages of mechanical ventilation (MV) are shown in (A). The model begins once the patient has completed the acute phase of ventilatory support and enters the recovery phase. The model is shown in (B). Patients receiving MV are either synchronous or asynchronous with the ventilator. Those who are synchronous can become asynchronous and vice versa. Patients receiving MV are at risk for ventilator-associated pneumonia (VAP). From MV, patients undergo a spontaneous breathing trial (SBT), which, if successful, results in liberation (extubation and removal from invasive MV). After liberation, patients are transferred to lower-acuity care (general ward [GW]) and later discharged home. If there is patient compromise after extubation (extubation failure), the endotracheal tube is reinserted and MV reinstituted. At any stage, patients may die. Note: ICU = intensive care unit, PAV+ mode = proportional-assist ventilation with load-adjustable gain factors, PSV = pressure-support ventilation.

Figure 2:

Cost-effectiveness plane for proportional-assist ventilation with load-adjustable gain factors (PAV+ mode) versus pressure-support ventilation (PSV). The dashed green line (reference) indicates a willingness-to-pay threshold of $50 000 per quality-adjusted life year (QALY) gained. Points underneath this line are considered cost-effective. Simulations in the lower right quadrant (increase in QALY, decrease in cost) are considered dominant. Costs are in 2017 Canadian dollars.

Figure 3:

Cost-effectiveness acceptability curve at 2 time horizons for proportional-assist ventilation with load-adjustable gain factors versus pressure-support ventilation. The proportion of simulations is shown according to varying thresholds of cost-effectiveness for a 1-year hospital-payer perspective and a 20-year public-payer perspective. Cases where the result was dominant (a decrease in costs accompanied by an increase in quality-adjusted life years) are counted among the cost-effective scenarios, hence the curves’ indicating nonzero proportions of simulations as cost-effective even at a willingness-to-pay threshold of $0. Costs are in 2017 Canadian dollars.