Peritonitis Rate Calculations

The most accurate peritonitis rate is one that is cumulative over a period of 12 months. Measuring peritonitis rates both for the individual patient and PD facility provides insight into the peritoneal dialysis outcomes leading to interventions that may improve results. Knowing peritonitis rates also allows for intercenter comparisons at different time points.

METHOD 1: Peritonitis Rate: One episode per number of patient months1

step 1

Total number CAPD/APD patient days at risk/30.4 days per month =
patient months experience

Example: 2,000 days/30.4 days per month = 65.8 months experience

step 2

Number of patient months/number of episodes of peritonitis = 1 episode per number of patient months

Example: 65.8 months/2 episodes = 32.9 or 1 episode every 32.9 patient months

METHOD 2: Peritonitis Rate: Episodes per patient year1

step 1

Total number CAPD/APD patient days at risk/365 days per year =
patient years experience

Example: 2,000 days/365 days per year = 5.5 years experience

step 2

Number of episodes of peritonitis/number of years experience =
Episodes per patient year

Example: 2 episodes peritonitis/5.5 patient years = 0.36 episodes per patient year

Important points:

  • Include hospital days (once home therapy begins) in total days at risk
  • Include hospital acquired peritonitis (once home therapy begins) in total peritonitis rate2
  • Relapsing episodes of peritonitis are counted as a single episode of peritonitis2
  • Recurrent peritonitis is a new episode of peritonitis and should be counted as an individual occurrence2
  • Peritonitis rates should be no more than 0.5 episodes per year at risk (one episode per 24 patient – months) per ISPD 2016 recommendations2
  • Programs should also be aware of the percentage of patients who are peritonitis free to include in unit’s quality management programs
  • Exit-site infection rates are calculated in the same manner as above