Objective: To investigate the
association of early
serum potassium level with all-cause
mortality in
adult maintenance hemodialysis (MHD)
patients .
Methods: It was a retrospective
cohort study . The data of
patients newly entered MHD in the registration system of Zhejiang province
dialysis quality control center from January 1, 2010 to December 31, 2019 were collected. Follow-up was conducted until December 31, 2020. The average value of predialysis
serum potassium within the first 3 months starting
hemodialysis was defined as early
serum potassium , and
patients were divided into 6 groups according to their early
serum potassium levels.
Death within 1 year of MHD
patients was defined as short-term
death . Kaplan-Meier
method was used to compare the long-term and short-term
survival rates of the six groups. Cox regression model was used to analyze the
association of different
serum potassium levels with the short-term all-cause
mortality of
adult MHD
patients .
Results: A total of 27 362
patients aged (61.2±14.4) years old were included, including 16 775
males (61.3%), 1 303
patients (4.8%) with
hypokalemia (
serum potassium <3.5 mmol/L) and 10 034
patients (36.7%) with
hyperkalemia (
serum potassium ≥5.0 mmol/L). Among them, there were 5 145
patients (18.8%) with
serum potassium ≥5.5 mmol/L. According to the early
serum potassium levels, the
patients were divided into group 1 (
serum potassium <3.5 mmol/L), group 2 (3.5≤
serum potassium <4.0 mmol/L), group 3 (4.0≤
serum potassium <4.5 mmol/L), group 4 (4.5≤
serum potassium <5.0 mmol/L), group 5 (5.0≤
serum potassium <5.5 mmol/L) and group 6 (
serum potassium ≥ 5.5 mmol/L), respectively. Until the end of follow-up, the follow-up
time was (40.7±27.8) months and 5 400
patients died. Cardiovascular and
cerebrovascular diseases [1 551 cases (28.7%)] and
infections [366 cases (6.8%)] were the main
causes of death . Kaplan-Meier
survival analysis showed that the long-term and short-term
cumulative survival rates in the
serum potassium <3.5 mmol/L group were the lowest among the 6 groups (Log-rank test, χ2=119.0, P<0.001; χ2=74.6, P<0.001, respectively). Multivariate Cox
regression analysis showed that early
serum potassium <3.5 mmol/L was an independent influencing factor for short-term all-cause
death in MHD
patients (with 4.5≤
serum potassium <5.0 mmol/L as reference, HR=1.54, 95% CI 1.26-1.89, P<0.001). In the subgroup of age≥65 years, multivariate Cox regression model showed that
serum potassium <4.5 mmol/L was independently associated with short-term
death in MHD
patients (with 4.5≤
serum potassium < 5.0 mmol/L as reference,
serum potassium <3.5 mmol/L, HR=2.16, 95% CI 1.69-2.75, P<0.001; 3.5≤
serum potassium <4.0 mmol/L, HR=1.40, 95% CI 1.14-1.72, P=0.001; 4.0≤
serum potassium < 4.5 mmol/L, HR=1.46, 95% CI 1.21-1.75, P<0.001), while in the subgroup of age<65 years,
serum potassium level was not significantly associated with short-term
mortality risk in MHD
patients . The early
serum potassium level was associated with the
risk of short-term all-cause
death in a "U" shape, and both low and high
potassium levels increased the
risk of short-term all-cause
death . The optimal early
blood potassium level was about 4.75 mmol/L.
Conclusions: The
prevalence of
hypokalemia at early stage of
dialysis in
adult MHD
patients is about 4.8%. There is a U-shaped
association between early
serum potassium level and short-term (1 year) all-cause
mortality risk , and early
serum potassium <3.5 mmol/L is an independent
risk factor for long-term and short-term all-cause
mortality in MHD
patients .