Combined impact of microalbuminuria and obesity on cardiovascular outcomes in hospitalized heart failure patients: a cohort study

BACKGROUND: Microalbuminuria is proven to be an early indicator of poor prognosis in patients with heart failure (HF), while the role of obesity in predicting progression and outcomes of HF is faced with controversies. Evidence probing into the combined effect of microalbuminuria and obesity on cardiovascular outcomes in hospitalized HF patients is still lacking. METHODS: Consecutive patients hospitalized for HF were retrospectively enrolled from the Heart Failure Care Unit of Fuwai Hospital. The primary outcome was a composite of cardiovascular death and rehospitalization for heart failure. Patients were classified into four categories based on BMI and UACR: (1) Nonobese/nUACR, (2) Nonobese/hUACR, (3) Obese/nUACR, and (4) Obese/hUACR. RESULTS: Ultimately, 2228 patients with HF were enrolled. Cox regression analysis confirmed that microalbuminuria was independently associated with the primary outcome (HR 1.28, 95%CI 1.01-1.62, p = 0.038). Obesity was independently associated with the primary outcome in main analysis (HR 1.42, 95% CI 1.08-1.86, p = 0.013), but the association became insignificant after excluding NT-proBNP from covariates. Using Nonobese/nUACR as reference, Obese/nUACR and Obese/hUACR were related to an equally 61% increase in risk of the primary outcome (HR 1.61, 95% CI 1.1-2.37, p = 0.015; HR 1.61, 95% CI 1.1-2.34, p = 0.014, respectively), higher than Nonobese/hUACR. Component analysis showed that Obese/hUACR was associated with a significantly increased risk of rehospitalization (HR 1.89, 95% CI 1.06-3.4, p = 0.032) but not with cardiovascular death after adjustment. Restricted cubic spline (RCS) demonstrated nonlinear relationships of UACR elevation and risk (p < 0.001). In the subgroup of HFpEF, the association of Obese/hUACR with the primary outcome persisted (HR 3.81, 95% CI 1.87-7.76, p < 0.001, p for interaction = 0.241). CONCLUSIONS: Overlapping of obesity and microalbuminuria is relatively common (8.7%) in hospitalized HF patients. The coexistence of obesity and microalbuminuria is an independent risk factor for poor outcomes but in obese patients, the addition of microalbuminuria may not provide incremental prognostic information. The association with primary composite outcome appears to be primarily driven by rehospitalization rather than cardiovascular death. Subgroup findings in HFpEF population may be valuable but still warrant validation. (NCT02664818).