Analysis of the Lung Allocation Score Estimation of Risk of Death in Patients With Pulmonary Arterial Hypertension Using Data From the REVEAL Registry

Background. Waitlist mortality for patients with pulmonary arterial hypertension (PAH) has not improved after implementation of the lung allocation score (LAS). We analyzed data from patients in the Registry to Evaluate Early and Long-term PAH Disease Management (REVEAL) as a means to compare observed mortality with predicted mortality from the LAS to identify key prognostic parameters that may be incorporated into the LAS to improve waitlist mortality for patients with PAH. Methods. Of the 2967 patients with PAH enrolled in REVEAL, 2327 had all required variables available to compute the LAS. Univariable and multivariable analyses were conducted to compare waitlist survival predicted by the LAS formula with that observed in the REVEAL cohort. Results. Two variables were independently associated with increased mortality compared with that predicted by the LAS in multivariable analysis using a Cox proportional hazards model: mean right atrial pressure (mRAP) more than or equal to 14 mm Hg and 6-min walk test distance (6-MWD) less than or equal to 300 m. A modified LAS system was developed, updating the waitlist survival component of the calculation as follows: modified waitlist exponent equals original waitlist exponent plus 0.7; if mRAP is more than or equal to 14 mm Hg, minus 0.35; for every 100 m of 6-MWD, plus 1.0. Conclusions. The LAS is reevaluated every 6 months after the initial 3-year trial period. Our results suggest that an LAS model that includes both 6-MWD and mRAP better discriminates waitlist urgency for patients with PAH than the current LAS.