Low-normal serum potassium is associated with an increased risk of cardiovascular and all-cause death in community-based elderly.

Background/purpose: Several studies have already reported that serum potassium (SK) correlated inversely with adverse events among patients with preexisting cardiovascular disease and impaired renal function; less is known about the prognostic value of SK at the normal range in community-based elderly individuals. This study aimed to examine whether low normal SK value was associated with cardiovascular and all-cause mortalities in elderly people.

Methods: A prospective study was conducted using two independent elderly Taiwanese community cohorts that included 2065 individuals with relatively normal SK values (2.8-5.6 mmol/L). The participants were grouped as follows: low (2.8-3.4 mmol/L), low-normal SK (3.5-3.8 mmol/L), normal (3.9-4.4 mmol/L), and high-normal SK (4.5-5.6 mmol/L). Proportional hazards model was applied to compare the association between SK concentration groups and mortality.

Results: The relationship between baseline SK and all-cause and cardiovascular mortality was U-shaped, with the lowest mortality rates observed in patients with SK levels of 3.9-4.4 mmol/L. The low-normal SK group had significantly higher risks of all-cause (hazard ratio, 1.3; 95% confidence interval, 1.0-1.6) and cardiovascular mortality (hazard ratio, 1.6; 95% confidence interval, 1.1-2.3) than the normal SK group. The high-normal SK group had higher but nonsignificant risk compared to the normal group.

Conclusion: Our findings suggest that low-normal SK may be used as a marker of poor survival for elderly outpatient cares.