Presence and outcomes of kidney disease in patients with pulmonary hypertension

Abstract

Background and objectives Pulmonary hypertension is associated with higher mortality rates. The associations of nondialysis-dependent CKD and all-cause mortality in patients with pulmonary hypertension were studied. Design, setting, participants, & measurements The study population included those patients who underwent right heart catheterization for confirmation of pulmonary hypertension between 1996 and January 2011. Pulmonary hypertension was defined as the presence of mean pulmonary artery pressure≥25 mmHg at rest measured by right heart catheterization. CKD was defined as the presence of two measurements of eGFR<60 ml/min per 1.73 m2 90 days apart. The risk factors associated with CKD as well as the association between CKD and death in those patients with pulmonary hypertension using logistic regression and Cox proportional hazard models were examined. Results Of 1088 patients with pulmonary hypertension, 388 (36%) patients had CKD: 340 patients had stage 3 CKD, and 48 (4%) patients had stage 4 CKD. In the multivariable analysis, older age, higher hemoglobin, and higher mean right atrial pressures were independently associated with CKD. During a median follow-up of 3.2 years (interquartile range=1.5-5.6 years), 559 patients died. After adjusting for relevant covariates, presence of stage 3 CKD (hazard ratio, 1.37; 95% confidence interval, 1.14 to 1.66) and stage 4 CKD (hazard ratio, 2.69; 95% confidence interval, 1.88 to 3.86) was associated with all-cause mortality in those patients with pulmonary hypertension. When eGFR was examined as a continuous measure, a 5 ml/min per 1.73 m2 lower eGFR was associated with a 5% (95% confidence interval, 1.03 to 1.07) higher hazard for death. This higher risk with CKD was similar irrespective of demographics, left ventricular function, and pulmonary capillary wedge pressure. Conclusion In a clinical population referred for right heart catheterization, presence of CKD was associated with higher all-cause mortality in those patients with pulmonary hypertension. Mechanisms that may underlie these associations warrant additional studies.