Validation of existing risk scores for worsening renal function in patients with newly diagnosed heart failure: a longitudinal population cohort study

Background
Worsening renal function (WRF) is one of the strongest predictors of outcome in patients with heart failure (HF). The presence of WRF often influences the decision to start, up-titrate, or discontinue disease-modifying HF therapies and is one of the key determinants of suboptimal guideline-directed medical therapy. However, there are now potential cardiovascular pharmacotherapies that have favourable cardiorenal outcomes and reduce the risk of renal decline. It is therefore important to identify patients with HF early in their disease trajectory who are at risk of developing WRF.

Purpose
The aim of this study was to evaluate two existing WRF risk scores (the Forman risk score and the Basel risk score) in a population-based longitudinal cohort diagnosed with incident HF.

Methods
Data for individuals with incident HF between 2016 to 2021 were extracted and analysed from the NELSON study conducted in Tayside, Scotland. WRF was defined as a composite event of (i) having two consecutive eGFRs declined by 40% or greater; (ii) having an eGFR < 15mL/min/1.73m2; (iii) initiation of sustained dialysis; (iv) development of end-stage kidney disease; or (v) receiving kidney transplantation. The primary outcome was the occurrence of WRF within 180 days of diagnosis of HF. Among patients hospitalised with HF, in-hospital WRF was also assessed. The area under the curve (AUC) was used to assess the discrimination performance of the two risk scores in individuals with incident HF diagnosed as either in-patients or out-patients.

Results
4076 individuals (mean age 72.8 ± 13.2; 58% male; 1081 HFrEF, 646 HFmrEF, 1348 HFpEF, and 1001 HF with unknown ejection fraction (EF)) who were WRF-free at incident HF diagnosis were identified. Of these, 2095 (51.4%) were diagnosed as in-patients, and 1981 (48.6%) were diagnosed as out-patients. 285 (7%) patients developed WRF within 180 days post HF diagnosis. Among the 2,095 HF in-patients, 75 (3.6%) developed WRF before discharge. The Forman risk score had an AUC of 0.618 (95% CI: 0.585 – 0.651) in predicting 180-day WRF, and an AUC of 0.650 (0.587 – 0.713) for in-hospital WRF. The Basel risk score showed similar discriminating performance with an AUC of 0.618 (0.585 – 0.651) for 180-day WRF, and 0.656 (0.593 – 0.719) for in hospital WRF.

Conclusions
In a contemporary population, conventional risk scores such as the Forman or Basel risk scores have limited discrimination in predicting WRF in incident HF. New models with better discrimination for WRF prediction are therefore needed.