Renal function modifies the association between hemoconcentration and outcomes in hospitalized heart failure patients

Evidence-based management of decongestion is lacking in hospitalized heart failure (HHF) patients, especially in patients with impaired renal function. Hemoconcentration is an objective measure of decongestion that portends a favorable prognosis and guides management in HHF patients with preserved renal function. We aim to investigate whether it remains a prognosticator in patients with renal impairment, and to refine the identification of subpopulations who will benefit from hemoconcentration-guided therapy. HHF patients admitted to Heart Failure Center of Fuwai Hospital were consecutively included from December 2006 to June 2018. Patient characteristics were depicted. Relationships between in-hospital hemoconcentration, worsening renal function (WRF), and one-year all-cause mortality were investigated in the total population and compared between renal function groups using survival analysis and cubic splines, with a special focus on renal function-based interactions. The association was further validated in sensitivity analyses. Clinically relevant cut-offs and subpopulations were identified by subpopulation treatment effect pattern plots (STEPP) and subgroup analysis. 3661 participants (30.4% with impaired renal function) were included. Hemoconcentration, reflected by an in-hospital increase in hemoglobin, hematocrit, or a relative reduction in estimated plasma volume from baseline to discharge, was predictive of decreased one-year mortality in the total cohort despite its correlation with higher WRF incidence. The prognostic value of hemoconcentration differed in patients with impaired and preserved renal function. Hemoconcentration was related to a favorable prognosis in patients with preserved renal function (HR, 0.69; 95% CI, 0.53-0.90; P = 0.007), especially in young male patients with New York Heart Association functional class III-IV, reduced ejection fraction, and baseline eGFR > 75 mL/min/1.73m². Contrarily, impaired renal function patients experienced a higher incidence of WRF, and hemoconcentration was no longer related to outcome (HR, 0.90; 95% CI, 0.64-1.26; P = 0.545), with findings consistent in all clinically relevant subgroups. In HHF patients, the prognostic value of hemoconcentration differs by renal function, and the clinical utility of hemoconcentration is contingent on preserved renal function.