Kidney failure risk equation and health inequalities in routine care
The identification of individuals with chronic kidney disease (CKD) with the greatest risk of progressing to end-stage kidney disease (ESKD), and thus the greatest potential benefit of receipt of specialist nephrology services, is challenging. Prediction models, such as the kidney failure risk equation (KFRE), aim to estimate an individual’s risk of ESKD using clinical and demographic information. In 2021, NICE incorporated the KFRE into its guidelines for referral of patients with CKD to secondary care.
One of the variables used by the KFRE is urine albumin–creatinine ratio (uACR), testing of which has historically been low. The present retrospective cohort study used data collected from 2013 to 2022 on approximately 1.4 million people in the Greater Glasgow & Clyde area in Scotland. It set out to discover which demographic variables were associated with availability of uACR results; if referral criteria that included KFRE identified those at high risk of ESKD earlier than historic criteria based on eGFR; and the predictive performance of KFRE (for individuals who had uACR results).
Analysis found that a uACR measurement was available in 44.5% of 10,874 adults with CKD (G3–5). Characteristics independently associated with a lack of uACR testing were being female (aOR, 0.86 [95% CI, 0.79–0.93; P<0.001]), older age (age >80 years [0.75 (0.51–1.10)], versus those of 18–39 years) and a diagnosis of hypertension (0.69 [0.63–0.77; P<0.001]). Those associated with being tested were a diagnosis of diabetes (2.35 [2.14–2.58; P<0.001]) and living in the least deprived areas (1.11 [1.00–1.23; P<0.014]).
Of 1352 people with incident kidney failure during the study period, the 2021 NICE criteria (incorporating the KFRE) identified 116 people for referral earlier than the previous 2014 criteria. These individuals were more likely to meet the criteria ≥365 days before experiencing kidney failure (HR, 0.11 [0.02–0.83; P=0.032]). The mean time for meeting the criteria prior to kidney failure was 6.2 (SD, 2.3) years for NICE 2021, compared to 3.9 (SD, 2.5) years for NICE 2014.
The analysis of the predictive performance of the KFRE included 4838 adults with CKD. The highest values were found in males, adults aged 40–50 years, people with diabetes and people from the most deprived areas. KFRE produced good discrimination at predicting kidney failure at 5 years, with an area under the curve of 0.81.
The study highlights that the KFRE effectively predicts the risk of kidney failure in people with CKD and can be used to guide referrals to renal clinics. However, uACR testing rates are low and must be improved so that it can be used effectively. Furthermore, there is an urgent need to optimise screening within disadvantaged populations to prevent inequities in uACR testing impacting appropriate prevention of, and care for, ESKD.
The full article can be read here.
