Peritoneal dialysis (PD)-associated peritonitis is a significant source of morbidity, dialysis-related treatment costs, and is the leading cause of permanent transfer to hemodialysis (HD). Here, we sought to understand if the risks of peritonitis and peritonitis-related outcomes differ by country and to identify patient and clinic/facility predictors of peritonitis. Peritonitis infection data from PDOPPS 1 (2015-2018) in Australia/New Zealand, Canada, Japan, Thailand, the UK, and the US were analyzed. Infections occurring within 21 days of a previous case, or infection by the same organism within 50 days of initial presentation were excluded per ISPD guidelines. We investigated several facility and patient factors associated with peritonitis using covariate-adjusted proportional-rates models. We estimated the proportion of events with cure, hospitalization, re-infection, catheter removal, permanent HD transfer, or death within 50 days of initial presentation using covariate-adjusted logistic regression models. Adjustment variables included age, sex, black race (US only), ESRD vintage, serum albumin, residual Kt/V, and 13 summary comorbidities. During 7455 patient-years of observation, we observed 1677 peritonitis events among 4618 patients across 143 facilities. Peritonitis rates (episodes per patient-year) varied from 0.19 in Japan to 0.27 in Australia/ New Zealand (TABLE). Gram-positive peritonitis rates ranged from 0.06 in Thailand to 0.11 in Australia/New Zealand and Canada. Gram-negative peritonitis rates ranged from 0.03 in Japan to 0.07 in Thailand. Culture negative peritonitis rates were highest in Thailand (0.07). The proportion of cases cured with antibiotics ranged from 55% in Thailand to 68% in Japan. The proportion of cases complicated by technique failure or death ranged from 16% in Japan to 27% in Thailand (TABLE). In adjusted analyses, lower peritonitis rates were observed in patients with higher serum albumin (HR=0.89 per 1 g/dl; 95% CI=0.80, 0.98), higher residual Kt/V (HR=0.79; 95% CI=0.65, 0.98); higher peritonitis rates were observed in patients with GI bleeding (HR=1.45; 95% CI=1.04, 2.02). Lower peritonitis rates were associated with facility use of antibiotic prophylaxis during catheter insertion (HR=0.68, 95% CI=0.52, 0.88) and use of exit-site gentamicin prophylaxis (HR=0.86, 95% CI=0.59, 1.25) or exit-site mupirocin prophylaxis (HR=0.83, 95% CI=0.61, 1.12) compared to none.View Large Image Figure ViewerDownload Hi-res image Download (PPT) In the largest international cohort of PD patients to date, we have demonstrated significant variations in peritonitis incidence and outcomes by country. In Thailand, a PD-first country with more limited resources, peritonitis incidence was comparable to other countries. However, a higher culture-negative peritonitis rate and significantly higher peritonitis-related adverse outcomes in Thailand compared to other countries (higher death, lower cure) suggest opportunities to improve peritonitis diagnosis and treatment. As a clinical practice, exit-site antimicrobial prophylaxis remains a mainstay of peritonitis prevention. Further investigation into the optimal exit site antimicrobial agent will be explored in PDOPPS along with other peritonitis prevention strategies.