Methods: In the EQUAL study, a European prospective cohort study, patients with advanced CKD of ≥65 years and a kidney function that dropped below 20 mL/min/1.73m2 were followed for one year. Linear mixed effects models were used to assess the association between kidney function decline and symptom development. The sum score for symptom number ranged from 0-33 and for overall symptom severity from 0-165, using the Dialysis Symptom Index.
Results: At least one kidney function estimate with symptom number or overall symptom severity was available for 1109 and 1019 patients, respectively. The mean (95%-confidence interval) annual kidney function decline was 1.70 (1.32; 2.08) mL/min/1.73m2. Mean overall increase in symptom number and severity was 0.73 (0.28; 1.19) and 2.93 (1.34; 4.52) per year, respectively. A cross-sectional association between level of kidney function and symptoms was lacking. Furthermore, kidney function at cohort entry was not associated with symptom development. However, each mL/min/1.73m2 of annual kidney function decline was associated with an extra annual increase of 0.23 (0.07; 0.39) in the number of symptoms and 0.87 (0.35; 1.40) in overall symptom severity.
Conclusions: A faster kidney function decline was associated with a steeper increase in both symptom number and severity. Considering the modest association, our results seem to suggest that repeated thorough assessment of symptom development during outpatient clinic visits, in addition to the monitoring of kidney function decline, is important for clinical decision-making.
- chronic kidney disease
- clinical epidemiology
- kidney function
- kidney function decline