Risk factors for death of patients with cystic fibrosis awaiting lung transplantation

Abstract

Rationale: The optimal timing for listing of cystic fibrosis patients for lung transplantation is controversial.

Objectives: We conducted a retrospective cohort study of 343 patients listed for lung transplantation at four academic medical centers to identify risk factors for death while awaiting transplantation.

Methods: Data on possible risk factors were abstracted from medical records.

Measurements: Time to death, patient demographic characteristics, and risk factors for death while awaiting transplantation were assessed. Univariate and multivariate survival analyses were performed using Cox regression.

Results: By univariate analyses, FEV1 < or = 30% predicted (HR, 3.8; 95% CI, 2.0-7.5), Pa(CO2) > or = 50 mm Hg (HR, 1.85; 95% CI, 1.1-3.0), and shorter height (HR, 1.8; 95% CI, 1.1-3.0) were associated with a higher risk of death. Referral from an accredited cystic fibrosis center was associated with a lower risk (HR, 0.53; 95% CI, 0.30-0.92). The final multivariate model included referral from an accredited cystic fibrosis center (HR, 0.5; 95% CI, 0.3-1.0) and listing year after 1996 (HR, 0.4; 95% CI, 0.2-0.7); both were associated with a lower risk of death. FEV1 < or = 30% predicted (HR, 6.8; 95% CI, 2.4-19.3), Pa(CO2) > or = 50 mm Hg (HR, 6.9; 95% CI, 1.5-32.1), and use of a nutritional intervention (HR, 2.3; 95% CI, 1.3-4.1) were associated with increased risk. Patients with FEV1 > 30% predicted had a higher risk of death only when their Pa(CO2) was > or = 50 mm Hg (HR, 7.0; 95% CI, 1.5-32), while the increased risk of death with FEV1 < or = 30% was not further influenced by the presence of hypercapnia.

Conclusions: We identified risk factors for waiting list mortality that could impact on transplant listing and allocation guidelines.

Figure 1.

Kaplan-Meier survival plot of the proportion of patients with cystic fibrosis awaiting lung transplantation, based on a cutoff in FEV₁ of 30% predicted. The p value from the log-rank test is less than 0.01. Solid line, FEV₁ > 30% predicted; dashed line, FEV₁ ⩽ 30% predicted.