In patients with heart failure, kidney dysfunction and abnormalities are associated with serum electrolyte levels are associated with poor clinical outcomes. However, how does visit-to-visit variability in kidney function affect long-term outcomes is unclear. This study aims to examine the association of visit-to-visit variability in kidney function and serum electrolyte with the risk of adverse clinical outcomes.

This cohort analysis included a total of 3,445 participants aged 68-69 years with 3 or more serial laboratory measurements, which were event-free for the first 4 months of enrollment. The primary outcome of this study was the adjusted association between indexes of variability in serum laboratory measurements and adverse cardiovascular outcomes.

The findings suggested that patients with higher laboratory variability in kidney function were older, had more severe symptoms of HFpEF, and had more comorbidities. Higher visit-to-visit variability in BUN and creatine was independently associated with a higher risk of primary composite outcome and mortality. The prevalence of primary outcome and mortality was independent of changes in medication dosages, changes in kidney function, and other baseline cofounders.

 The research concluded that HFpEF, serum electrolytes, and visit-to-visit variability in kidney function were independently associated with all-cause mortality and other adverse clinical outcomes.