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**Objective: **To evaluate the impact of the "flush before fill" technique on the frequency of peritonitis in children receiving automated peritoneal dialysis (APD). DESIGN: Randomized prospective multicenter study. SETTING: Participating pediatric dialysis programs of the Pediatric Peritoneal Dialysis Study Consortium.

**Year:** 2003

**Source:** Peritoneal Dialysis International

**Link:** http://www.pdiconnect.com/content/23/5/493.short

**Clinical Area: **Nephrology

Sample Size Section in Paper/Protocol: |

“Calculation of the required sample size was based on the assumption that the introduction of the flush-before-fill technique would reduce the peritonitis rate from a baseline study value of 1 infection every 12 patient months to 1 infection every 24 patient months. With a two-sided test, an alpha level of 0.05, and a power of 80%, the analysis required 48 patients per group and 566 patient months per group” |

**Note: **Rates are converted to years rates due to study being for 1 year.

Summary of Necessary Parameter Estimates for Sample Size Calculation:

Parameter |
Value |

Significance Level (2-Sided) | 0.05 |

Expected Placebo Rate | 1 |

Expected Treatment Mean | 0.5 |

Power | 80% |

**Step 1: **

Select the **Two Group Test of Incidence Rates** **using Normal Approximation **table from the Select Test Design & Goal window.

This can be done **using the radio buttons** or alternatively, you can** use the search bar** at the end of the Select Test Design & Goal window.

**Step 2:**Enter the parameter values for sample size calculation taken from the study design.

**Step 3:**Select

This gives a sample size of 48 per group (since study was one year long) with power of 80.7% |

**Step 4:**Once the calculation is completed, nQuery Advanced provides an output statement summarizing the results. It States:

Output Statement: |

A 2 sided comparison of two incidence rates in terms of person years in a fully randomized trial with a sample of 48 person-years per group would achieve 80.74% power at the 0.05 significance level to detect a difference in incidence rates of at least 0.5 if the control group incidence rate was 1. |

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