RESUMEN
Donor-derived cell-free DNA (dd-cfDNA%) is a biomarker of early acute lung allograft dysfunction (ALAD), with a value of ≥1.0% indicating injury. Whether dd-cfDNA% is a useful biomarker in patients >2 y posttransplant is unknown. Our group previously demonstrated that median dd-cfDNA% in lung recipients ≥2 y posttransplant without ALAD was 0.45%. In that cohort, biologic variability of dd-cfDNA% was estimated by a reference change value (RCV) of 73%, suggesting that change exceeding 73% may be pathologic. In this study, we aimed to determine whether dd-cfDNA% variability or absolute thresholds are optimal for detecting ALAD. Methods: We prospectively measured plasma dd-cfDNA% every 3 to 4 mo in patients ≥2 y post-lung transplant. ALAD was defined as infection, acute cellular rejection, possible antibody-mediated rejection, or change in forced expiratory volume in 1 s >10%, and was adjudicated retrospectively. We analyzed area under the curve for RCV and absolute dd-cfDNA% and reported performance of RCV ≥73% versus absolute value >1% for discriminating ALAD. Results: Seventy-one patients had ≥2 baseline measurements of dd-cfDNA%; 30 developed ALAD. RCV of dd-cfDNA% at ALAD had a greater area under the receiver operator characteristic curve than absolute dd-cfDNA% values (0.87 versus 0.69, P = 0.018). Test characteristics of RCV >73% for ALAD diagnosis were sensitivity 87%, specificity 78%, positive predictive value 74%, and negative predictive value 89%. In contrast, dd-cfDNA% ≥1% had sensitivity 50%, specificity 78%, positive predictive value 63%, and negative predictive value 68%. Conclusions: Relative change in dd-cfDNA% has improved test characteristics for diagnosing ALAD compared with absolute values.
RESUMEN
Donor-derived cell-free DNA (dd-cfDNA) is a useful biomarker for the diagnosis of acute allograft injury within the first 1 to 2 y after lung transplant, but its utility for diagnosing chronic lung allograft dysfunction (CLAD) has not yet been studied. Understanding baseline dd-cfDNA kinetics beyond the initial 2 y posttransplant is a necessary first step in determining the utility of dd-cfDNA as a CLAD biomarker. We seek to establish baseline dd-cfDNA% levels in clinically stable lung allograft recipients who are >2 y posttransplant. Methods: We performed a prospective, single-center, observational study to identify plasma dd-cfDNA levels in clinically stable lung allograft recipients >2 y posttransplant. Results: Fifty-one subjects were enrolled and ≥3 baseline dd-cfDNA measurements were acquired during a median of 252 d. The median baseline percent dd-cfDNA level in our cohort was 0.45% (interquartile range [IQR], 0.26-0.69). There were statistically significant differences in dd-cfDNA based on posttransplant duration (≤5 y posttransplant median 0.41% [IQR, 0.21-0.64] versus >5 y posttransplant median 0.50% [IQR, 0.33-0.76]; P < 0.02). However, the clinical significance of this small change in dd-cfDNA is uncertain because this magnitude of change is within the biologic test variation of 73%. Conclusions: This study is the first to define levels of dd-cfDNA in clinically stable patients who are >2 y post-lung transplant. These findings lay the groundwork for the study of dd-cfDNA as a possible biomarker for CLAD.
RESUMEN
BACKGROUND: Epoprostenol significantly improves function and survival in patients with pulmonary arterial hypertension (PAH) but is associated with many risks and side effects. Furthermore, effective oral therapy is now available. We report our long-term experience with 13 patients from among 118 treated with epoprostenol who were able to be weaned to oral therapy, including 6 with persistently abnormal hemodynamics (mean pulmonary artery pressure > or = 35 mm Hg). METHODS: Oral therapy with bosentan (n = 11) or sildenafil (n =2) was started before weaning epoprostenol in all but 1 patient. Right heart catheterization was performed when patients reached a dose of 2 ng/kg/min, and epoprostenol was discontinued with hemodynamic monitoring. Functional class and 6-minute walk test were assessed at regular intervals. Repeat right heart catheterization was performed 1 year after discontinuation of epoprostenol. RESULTS: Nine patients remained on oral therapy alone for up to 46 months. Four patients deteriorated in functional class, and 2 of them resumed epoprostenol therapy. Inhaled iloprost was started in another patient. One additional patient died, unrelated to PAH. Twelve patients underwent right heart catheterization at the time of epoprostenol discontinuation. Hemodynamic evaluation 13.2 +/- 0.9 months later showed that the 5 patients with normal or nearly normal hemodynamics at the time of discontinuation of epoprostenol had no deterioration, whereas 4 of the 7 patients with abnormal hemodynamics had worsened. The 6-minute walk test at last follow-up was not significantly changed from maximal distance on epoprostenol (420 +/- 94 vs 412 +/- 95 meters). CONCLUSION: Weaning from epoprostenol to sildenafil or bosentan with sustained clinical improvement is possible, even with persistent pulmonary hypertension; however, patients with persistently abnormal hemodynamics are at risk for hemodynamic and clinical deterioration and require close follow-up.
