Peritonitis Rates in Capd Patients

1

A COMPARISON OF

PERITONITIS RATES IN CAPD PATIENTS

APRIL 1998 – MARCH 1999

Prepared By:

Nicola AusterberryRenal Audit Facilitator

Dr R. CowardConsultant Nephrologist
INTRODUCTION

1Within the North West Region, peritonitis rates for Continuous Ambulatory Peritoneal Dialysis (CAPD) are being monitored through a continuously running audit which is reported annually.

2This report will present the results for the eighth Peritonitis Audit covering the period April 1998 -March 1999. Where appropriate, the standards detailed in the Renal Association publication November 1997 -‘Treatment of adult patients with renal failure: Recommended standards and audit measures’ (Second Edition) have been utilised.

PURPOSE

3The purpose of the audit is to compare the incidence of peritonitis between the Regions adult renal units. The aims of the audit were to analyse peritonitis rates and treatment response rates in relation to:

• the unit
• the dialysis system
• the organism

PARTICIPATING RENAL UNITS

4The five adult renal units in the North West Region are:

• Withington Hospital
• Hope Hospital
• Manchester Royal Infirmary
• Royal Preston Hospital
• Royal Liverpool University Hospital

Also included is data collected at Furness General Hospital, a satellite of Royal Preston Hospital

METHODOLOGY

5The methodology remains unchanged for this audit. The audit is concurrent in design. When a patient presents with an episode of peritonitis, the data is recorded on a standardised proforma by the nursing staff at each unit.

6All patients on the CAPD programme throughout the audit period are included in the population.

Summary of Results

7The average patient population at each unit has been calculated as the mean number of patients at each unit at the beginning and end of the audit period. Analysis has been carried out using the mean population.

8A mean population of 635 patients were treated with CAPD during this audit period. The distribution between units is shown below:

9Gender of the CAPD population as a whole

10The table below illustrates data about the audit population:

11During this audit period, 297 patients (47% of the total CAPD population) had one or more episodes of peritonitis. 55% were male compared to 45% female.

Peritonitis Occurrence

12The Renal Association standard forthe occurrence of peritonitis is used as a measure for the audit. The Association states:

The recommended minimum standard using the disconnect system is:

Peritonitis rates should be <1-episode/18 patient-months.

(Renal Association November 1997)

Although this standard is for use with the disconnect system it is used as a measure for all CAPD systems in this audit.

13The following table details peritonitis rates expressed as episodes per patient year and patient months per episode:

14Peritonitis rates, expressed as patient months per episode, for this current period are compared to the data for the previous four audits in the table below:

15A total of 422 episodes of peritonitis were reported in 297 patients during the audit period. The distribution of episodes across the units is illustrated in the table below:

16Three CAPD systems continue to be used across the region, standard, disconnect, and sterilisation. The following table displays the mean number of patients reported using the different systems during the audit period:

17The number of peritonitis episodes reported for each system is illustrated below:

18The following table details the peritonitis rates as patient months per episode for each system:

Microbiology

19The negative peritoneal fluid culture rate in patients with clinical peritonitis should be less than 10%

Renal Association November 1997

This standard is the second measure used in this audit. It has been found difficult to comply with over the previous audit periods and continues so during this current period. The Renal Association document (November 1997) gives guidelines for the culture of PD fluid and a recommendation of this report is that each unit reviews its no bacterial growth rate and methods of fluid culture.

20 The following table illustrates the percentage of infection caused by no bacterial growth for this current audit period in comparison to the previous three:

21The organisms responsible for causing the reported episodes of peritonitis are expressed as percentages of all infections in the table below (Staph epidermis is classified CNS):

22The following table shows a break down of causative organisms for peritonitis at each unit:

Outcomes

23The initial cure rate of peritonitis should be more than 80% (without necessity to remove the catheter).

Renal Association November 1997

24Of the 422 reported episodes of peritonitis, 322 (76%) responded to the initial antibiotic therapy. Another 13 episodes responded to further antibiotic therapy. The response rate for each unit is shown in the table below:

RLUH are the unit with the highest use of disconnect systems but the lowest response to treatment rate and the highest failure to respond to treatment.

25The regional average figures for initial cure rate have never reached the 80% recommended by the Renal Association although none of the units show consistently poor performance. The percentage of episodes responding to initial treatment for the current period is compared to the previous three audit periods in the table below:

Response according to microbiological organism

26The percentage of each group of organisms responsible for those episodes not responding to treatment are tabled below:

27The outcome of episodes failing to respond to treatment is detailed in the table below:

2812 episodes were reported as relapsed infections that failed to respond to further treatment. Of these relapsed episodes 11 resulted in catheter removal and 1 in catheter removal and reinsertion.

29The organisms responsible for the relapsing episodes of peritonitis which did not respond to further treatment, are shown in the table below:

30Catheter Removal

In total 54 episodes of peritonitis resulted in the catheter being removed. The following table details the causative organisms for these episodes:

Hospitalisation

31The following table shows the mean number of days (length of stay) per peritonitis episode [total number of days/total number of peritonitis episodes] for the current audit period compared with the previous two:

32174 episodes of peritonitis resulted in the patient being hospitalised.

20 episodes of peritonitis occurred whilst the patients were already in-patients.

33The following table illustrates the total number of admission days as a percentage of the whole CAPD population and the number of bed days per patient per year for each unit and the region as a whole:

34In-patient Episodes

Of the 20 episodes occurring during in-patients stays the following data has been recorded:

Systems being used at time of infection: 8 standard system

2 sterilisation

6 disconnect

4 IPD

Organisms causing infection6 gram negative

6 NBG

2 gram positive

2 Staph Aureus

1 mixed growth

1 CNS

2 Not recorded

Response to Therapy8 failed to respond

2 relapsed and failed to respond

1 relapsed and responded to further treatment

9 responded to treatment

Of the 10 episodes that did not respond to further treatment, 6 resulted in catheter removal and 4 patients died.

Conclusions and Recommendations

Peritonitis Occurrence

• Three out of the five units and the Region as a whole achieved the Renal Association standard for this audit period. Peritonitis rates should be <1-episode/18 patient-months. (Renal Association November 1997)

• Disconnect systems were the only systems to consistently achieve the Renal Association standard achieving one episode in 21.1 months.
• RLUH had the lowest peritonitis rates but also the lowest rates for response to treatment, high admission rates and long lengths of stay.

No Bacterial Growth Culture Rate:

• The Regional average rate over the past four years has never achieved the recommended Renal Association standard of<10%.
• Withington has consistently had the lowest rate of no bacterial growth (6%)
• RLUH with previously the highest rate of NBG continue to show a steady improvement and are now in line with the other units in the Region. (RLUH 22%)

Cure Rate for Peritonitis:

• The Regional average (76%) has never achieved the Renal Association standard of 80%.
• None of the units show consistently poor performance. Yearly variation is reflected by the change of organisms found in these periods of time in individual units.
• The lowest cure rate was 67% by RLUH, the unit with the highest use of the disconnect system, RPH who have a high percentage use of standard system have a 87% cure rate. The regional average is 79%.
• Use of disconnect systems has a low frequency of peritonitis but the organisms are usually more serious. This is illustrated by the lower than average staph aureus culture rate of 7% by RLUH compared to the regional average of 13%.

Hospitalisation

• There has been an increase in admissions in 4 out of 5 units.
• RLUH and SMUH have high admission rates 63% and 58% respectively compared to the regional average of 41% for peritonitis.

• The regional average for length of stay is 2.9 days. RLUH and SMUH have longer than average stays of 3.9 and 4.2 respectively.
• RPH have a high percentage use of standard systems but hospitalisation is 31% and average stay 1.2 days.

• There has been a regional decrease in peritonitis reported on inpatients.

General Summary

• 37% failure to respond was caused by gram negative organisms.
• 16 episodes were reported to relapse and not respond to further treatment.
• Regionally 50% of no response had catheters removed.
• The change to Disconnect Systems at MRI and Hope has improved their peritonitis rates to bring them in line with Renal Association Standards.
• A trend is appearing that use of disconnect systems is reducing incidence of Staph Aureus infection and increasing the percentage of gram-negative organisms. This is illustrated by RLUH whose reported staph aureus infection is 7% compared to the regional average of 13%.
• The increasing use of disconnect systems, though reducing the rates of peritonitis overall has highlighted the fact that when peritonitis occurs, it is usually of a more serious nature with prolonged hospitalisation and lack of cure, whilst the more trivial peritonitis (staphaureus) have been reduced with disconnect.

Recommendations

1. With universal change to disconnect systems throughout the region, the spectrum of organisms is isolated and cure rates need to be reviewed against historical data from the standard systems.
2. Increased emphasis should be put on morbidity and mortality complications of peritonitis rather than frequency of its occurrence as an index of quality of care.

NW Regional Peritonitis Audit/1998/9