Impact of worsening renal function in patients with incident heart failure across the spectrum of ejection fraction: a population-based longitudinal study

Abstract Background Renal dysfunction is a common occurrence in patients with heart failure (HF) and may impact on HF treatment and outcomes. HF clinical trial data suggest that worsening renal function (WRF) is associated with worse prognosis, however many of the medications used in HF cause a short-term decline in renal function that may improve in the longer-term. The real-world incidence and implications of WRF following an initial diagnosis of HF across the spectrum of ejection have not been well-characterised. Purpose The present study was designed to establish the incidence and outcomes associated with WRF in patients with incident HF on the risk of mortality and HF hospitalisation (hHF) in a real-world setting. Methods Electronic health records were linked to echocardiography data between 2016 to 2021 to define incident HF with reduced/mildly reduced/preserved EF (HFrEF/HFmrEF/HFpEF). Incidence of WRF at 6 months was determined as a composite endpoint of (i) having two consecutive eGFR declined by 40% or greater; (ii) having an eGFR <15 mL/min/1.73m^2; (iii) on sustained dialysis; or (iv) receiving kidney transplantation. Incidence of hHF and all-cause mortality were compared in HF patients with versus without WRF. We performed a stratified analysis according to baseline renal function (eGFR: >60, 45-59, 30-44, 15-29, or <15 mL/min/1.73m2). Results 4254 individuals were identified, 1100 HFrEF, 650 HFmrEF, 1252 HFpEF, and 1252 HF with unknown EF. Within 6 months of HF diagnosis, 592 patients died and 349 had WRF. Baseline eGFR <60 was present in 32% of individuals with HFrEF, 32% in HFpEF, 27% in HFmrEF, and 37% in HF with unknown EF. The incidence of WRF was similar in HFrEF (20.7 [95% CI: 16.9 – 25.1] per 100 person-years) and in HF with unknown EF (20.9 [17.1 – 25.3]), but was significantly lower in HFmrEF (13.6 [9.8 – 18.4]) and HFpEF (16.8 [13.7 – 20.5]). Patients with WRF were more likely to be female (adjusted hazard ratio [aHR]: 1.32 [1.06 – 1.64], p=0.014), having diabetes (1.34 [1.07 – 1.69], p = 0.012), and with lower baseline renal function (eGFR categories 45-59, 30-44, 15-29, or <15 compared with >60: aHR 1.75 [1.29 – 2.38], p<0.001; 1.64 [1.12 – 2.42], p=0.012; 5.65 [4.06 – 7.87], p<0.001; 90.74 [63.2 – 130.28], p<0.001). Individuals with WRF had significantly higher incidence of subsequent hHF (HR adjusted for age, sex, baseline renal function, and diabetes: 1.79 [1.35 – 2.39], p<0.001) and all-cause death (2.18 [1.66 – 2.88], p<0.001), compared to those without WRF. This was driven by patients diagnosed with HFrEF (2.46 [1.45 – 4.18], p<0.001) or HFpEF (3.45 [2.21 – 5.40], p<0.001), but was not seen in HFmrEF (1.91 [0.91 – 3.99], p=0.086) or HF within unknown EF (1.28 [0.65 – 2.52], p=0.484). Conclusion WRF is an important and common consequence following initial diagnosis of HF across the spectrum of EF with associated severe clinical outcomes in HF. Priority should be given to prevention of WRF in patients with incident HF.Impact of WRF on Clinical Outcomes