title: The association between peritoneal dialysis modality and peritonitis.
abstract: OBJECTIVE
  There is conflicting evidence comparing peritonitis rates among patients treated with continuous ambulatory peritoneal dialysis (CAPD) or automated peritoneal dialysis (APD). This study aims to clarify the relationship between peritoneal dialysis (PD) modality (APD versus CAPD) and the risk of developing PD-associated peritonitis.
  
  
  METHODS
  This study examined the association between PD modality (APD versus CAPD) and the risks, microbiology, and clinical outcomes of PD-associated peritonitis in 6959 incident Australian PD patients between October 1, 2003, and December 31, 2011, using data from the Australia and New Zealand Dialysis and Transplant Registry. Median follow-up time was 1.9 years.
  
  
  RESULTS
  Patients receiving APD were younger (60 versus 64 years) and had fewer comorbidities. There was no association between PD modality and time to first peritonitis episode (adjusted hazard ratio [HR] for APD versus CAPD, 0.98; 95% confidence interval [95% CI], 0.91 to 1.07; P=0.71). However, there was a lower hazard of developing Gram-positive peritonitis with APD than CAPD, which reached borderline significance (HR, 0.90; 95% CI, 0.80 to 1.00; P=0.05). No statistically significant difference was found in the risk of hospitalizations (odds ratio, 1.12; 95% CI, 0.93 to 1.35; P=0.22), but there was a nonsignificant higher likelihood of 30-day mortality (odds ratio, 1.33; 95% CI, 0.93 to 1.88; P=0.11) at the time of the first episode of peritonitis for patients receiving APD. For all peritonitis episodes (including subsequent episodes of peritonitis), APD was associated with lower rates of culture-negative peritonitis (incidence rate ratio [IRR], 0.81; 95% CI, 0.69 to 0.94; P=0.002) and higher rates of gram-negative peritonitis (IRR, 1.28; 95% CI, 1.13 to 1.46; P=0.01).
  
  
  CONCLUSIONS
  PD modality was not associated with a higher likelihood of developing peritonitis. However, APD was associated with a borderline reduction in the likelihood of a first episode of Gram-positive peritonitis compared with CAPD, and with lower rates of culture-negative peritonitis and higher rates of Gram-negative peritonitis. Peritonitis outcomes were comparable between both modalities.
authors.affiliation: Due to the number of contributing authors, the affiliations are provided in the Supplemental Material. plan1744@uni.sydney.edu.au.
authors.forename: Patrick G
authors.initials: PG
authors.lastname: Lan
authors.affiliation: Due to the number of contributing authors, the affiliations are provided in the Supplemental Material.
authors.forename: David W
authors.initials: DW
authors.lastname: Johnson
authors.affiliation: Due to the number of contributing authors, the affiliations are provided in the Supplemental Material.
authors.forename: Stephen P
authors.initials: SP
authors.lastname: McDonald
authors.affiliation: Due to the number of contributing authors, the affiliations are provided in the Supplemental Material.
authors.forename: Neil
authors.initials: N
authors.lastname: Boudville
authors.affiliation: Due to the number of contributing authors, the affiliations are provided in the Supplemental Material.
authors.forename: Monique
authors.initials: M
authors.lastname: Borlace
authors.affiliation: Due to the number of contributing authors, the affiliations are provided in the Supplemental Material.
authors.forename: Sunil V
authors.initials: SV
authors.lastname: Badve
authors.affiliation: Due to the number of contributing authors, the affiliations are provided in the Supplemental Material.
authors.forename: Kamal
authors.initials: K
authors.lastname: Sud
authors.affiliation: Due to the number of contributing authors, the affiliations are provided in the Supplemental Material.
authors.forename: Philip A
authors.initials: PA
authors.lastname: Clayton
mesh_terms: D000368:Aged; D018572:Disease-Free Survival; D005260:Female; D016905:Gram-Negative Bacterial Infections / Q000209:etiology; D016908:Gram-Positive Bacterial Infections / Q000209:etiology; D006760:Hospitalization; D006801:Humans; D008297:Male; D008875:Middle Aged; D010530:Peritoneal Dialysis / Q000009:adverse effects* / Q000379:methods*; D010531:Peritoneal Dialysis, Continuous Ambulatory / Q000009:adverse effects; D010538:Peritonitis / Q000209:etiology* / Q000382:microbiology / Q000401:mortality; D012307:Risk Factors
keywords: peritoneal dialysis; peritonitis; registry study