Acute asymptomatic C-reactive protein rise predicts short-term adverse events in peritoneal dialysis patients

C-reactive protein (CRP) is an acute inflammatory protein that increases in association with acute and chronic inflammation due to a range of causes, including infectious diseases and noninfectious inflammatory disorders and also in metabolic stresses. The purpose of this work was to determine whether acute CRP elevations above the baseline level in asymptomatic peritoneal dialysis (PD) patients could be associated with future short-term adverse events.

Medical records of chronic PD patients between the years 2012-2022 were reviewed retrospectively. Cases of acutely increased serum CRP during regular patient visits without a clinical picture of inflammation or infection were collected. Follow-up analysis of each such elevated serum CRP test was performed.

Overall 122 cases of acute increased CRP level were identified in patients who presented at regular visits in PD clinics without a clinical picture of infection or inflammation. Thirty-five patients (28.7%) developed an adverse event during the following month. CRP elevations that were associated with adverse events during the following month reached higher values compared to CRP elevations without adverse events, for any event - 58.97 ± 58.29 mg/l versus 31.67 ± 24.57 mg/l (p = 0.004), for severe event - 70.28 ± 62.26 mg/l versus 31.16 ± 24.67 mg/l (p = 0.001), for peritonitis - 54.95 ± 28.28 mg/l versus 37.81 ± 39.96 mg/l (p = 0.024) for hospitalization - 81.03 ± 72.27 mg/l versus 35.79 ± 32.91 mg/l (p = 0.010), and for the need for antibiotic treatment 70.40 ± 64.66 mg/l versus 33.07 ± 27.96 mg/l (p = 0.001). The area under the receiver operating characteristics (ROC) curve for serum CRP was 0.737 (range 0.606-0.869) for prediction of PD-related peritonitis (p = 0.007); 0.771 (range 0.639-0.902) for hospitalization (p = 0.005); 0.665 (range 0.552-0.778) for any adverse event (p = 0.005); 0.768 (range 0.664-0.873) for a severe adverse event (0.000) and 0.749 (range 0.631-0.868) for the need for antibiotic treatment (p = 0.000). Acute asymptomatic CRP elevations to a value above 50 mg/l were associated with increased risk of adverse events: Odd ratio was 3.119 (1.423, 6.836) p = 0.004 for any event, 4.727 (2.049, 10.904) p = 0.000 for severe event, 3.091 (1.064, 8.984) p = 0.038 for PD-related peritonitis, 5.023 (1.333, 18.931) p = 0.017 for hospitalization, and 3.698 (1.606, 8.518) p = 0.002 for antibiotic treatment. Multivariate analysis demonstrated that acutely elevated serum CRP above 50 mg/l was independently associated with any adverse event and severe adverse event during the next month after the elevation. Odd ratio was 2.769 (1.209, 6.343) p = 0.016 for any event and 4.065 (1.669, 9.902) p = 0.002 for severe adverse event.

Acute increase of serum CRP above 50 mg/l among asymptomatic PD patients was associated with future short-term adverse event. Therefore, routine follow-up of CRP may be considered in PD patients.