Association between serum potassium levels and peritonitis in peritoneal dialysis patients: a longitudinal study.

BACKGROUND: Abnormal serum potassium levels are common among peritoneal dialysis (PD) patients. Many studies have shown hypokalemia as a risk factor for peritonitis, but most were cross-sectional and observational. We intended to analyze the longitudinal association between serum potassium levels and peritonitis in those undergoing PD. METHODS: We included 1,288 patients undergoing regular PD at our institution. The endpoint event was peritonitis. Patients were divided into peritonitis and non-peritonitis groups. The relationship between baseline data and the emergence of peritonitis was analyzed through Cox regression analysis. Mixed-effects model was used to analyze the correlation between longitudinal serum potassium and other lab characteristics with peritonitis. Kaplan-Meier survival analysis estimated the median time to peritonitis.Independent samples t-test was used in subgroup analysis to explore the relationship between serum potassium and different pathogenic bacteria. Spearman correlation analysis and scatter plot were used to evaluate the correlation between serum potassium and magnesium. Cochran-Armitage trend chi-square test assessed the trend of peritonitis incidence. RESULTS: COX regression analysis found higher baseline lymphocyte count and female gender were associated with lower peritonitis risk, while older age and higher baseline uric acid levels were linked to higher risk. A mixed-effects model indicated that the peritonitis group’s serum potassium decreased more rapidly and remained low longer. Kaplan-Meier curves estimated the median time to peritonitis to be 4.09 years. The analysis of subgroups found no significant difference in serum potassium levels between the gram-positive and gram-negative bacteria groups. Spearman correlation analysis showed a very weak positive correlation between potassium and magnesium with poor trend consistency but statistical significance. Peritonitis incidence showed a significant linear downward trend from 2011 to 2023. CONCLUSIONS: Rapid declines and long-term low levels of serum potassium after PD initiation increase peritonitis risk. Long-term potassium management in PD patients is crucial in clinic practice, with intensified monitoring advised around 4 years into PD treatment. TRIAL REGISTRATION: 2023BA0125_GC; 2023-10-20.