The effect of pulmonary artery catheter use on costs and long-term outcomes of acute lung injury

Abstract

Background: The pulmonary artery catheter (PAC) remains widely used in acute lung injury (ALI) despite known complications and little evidence of improved short-term mortality. Concurrent with NHLBI ARDS Clinical Trials Network Fluid and Catheters Treatment Trial (FACTT), we conducted a prospectively-defined comparison of healthcare costs and long-term outcomes for care with a PAC vs. central venous catheter (CVC). We explored if use of the PAC in ALI is justified by a beneficial cost-effectiveness profile.

Methods: We obtained detailed bills for the initial hospitalization. We interviewed survivors using the Health Utilities Index Mark 2 questionnaire at 2, 6, 9 and 12 m to determine quality of life (QOL) and post-discharge resource use. Outcomes beyond 12 m were estimated from federal databases. Incremental costs and outcomes were generated using MonteCarlo simulation.

Results: Of 1001 subjects enrolled in FACTT, 774 (86%) were eligible for long-term follow-up and 655 (85%) consented. Hospital costs were similar for the PAC and CVC groups ($96.8k vs. $89.2k, p = 0.38). Post-discharge to 12 m costs were higher for PAC subjects ($61.1k vs. 45.4k, p = 0.03). One-year mortality and QOL among survivors were similar in PAC and CVC groups (mortality: 35.6% vs. 31.9%, p = 0.33; QOL [scale: 0-1]: 0.61 vs. 0.66, p = 0.49). MonteCarlo simulation showed PAC use had a 75.2% probability of being more expensive and less effective (mean cost increase of $14.4k and mean loss of 0.3 quality-adjusted life years (QALYs)) and a 94.2% probability of being higher than the $100k/QALY willingness-to-pay threshold.

Conclusion: PAC use increased costs with no patient benefit and thus appears unjustified for routine use in ALI.

Trial registration: www.clinicaltrials.gov NCT00234767.

Figure 1. Quorum chart of the EA-PAC cohort.

Figure 2. Survival by treatment arm.

Trends seen in the FACTT trial persist to one year of follow-up. Although patients with CVC have higher cumulative survival, the difference is not significant (p = 0.33, log-rank).

Figure 3. Utility by treatment arm.

Median Health-related quality-of-life, measured by the Health Utilities Index, is uniformly low in the EA-PAC cohort, although the inter-quartile range is wide and individual values spread the entire 0–1 interval. Utilities are lowest at 90 days and improved by 9 months. Subjects assigned to the PAC were no different than those assigned to the CVC.

Figure 4. Post-discharge resource use.

Overall post-discharge costs were significantly higher in patients assigned to the PAC. There was a trend in most categories of costs favoring CVC, but only post-discharge rehabilitation costs were significantly different. Of note, the difference was most apparent at the 9 and 12 month follow-up point (data not shown).

Figure 5. Cost-effectiveness of the Pulmonary Artery Catheter.

The mean estimate of incremental costs and effects suggest that the PAC is both more expensive and less effective (panel A). The 95% confidence ellipse only marginally dips below the 50 k/QALY willingness-to-pay threshold with the vast majority of trials agreeing with the mean estimate that the PAC is an inferior strategy. The corresponding cost-effectiveness acceptability curve conveys the probability of the PAC to be cost-effective at various willingness-to-pay thresholds (Panel B, x-axis). Even if willingness-to-pay was unlimited, there is only a 20.8% probability of the PAC to be cost effective (Panel B, dotted line). The PAC displays a better cost-effectiveness profile in subjects treated with a conservative fluid strategy (panel C) than those receiving a liberal strategy. A similar trend is seen in subjects where the study protocol was instituted early after enrolment (panel D). Yet, for both subgroups, there was a high probability for the PAC to be an ineffective strategy.