Introduction: Individual patient data metaanalysis has been described as the gold standard for systematic reviews of the effects of health care.

Objective:

To compare results of metaanalyses based on three different sources of information: (a) aggregate data extracted from published reports (ADP); (b) aggregate data supplied by study investigators (ADS); (c) individual patient data supplied by study investigators (IPD).

Methods:

RCTs on Selective Decontamination of the Digestive Tract (SDD) - a form of antibiotic prophylaxis for patients in intensive care units - have been searched and identified starting 1990. A total of 25 RCTs, totalling 4310 patients, was identified. For this analysis 17/25 RCTs for which all the three sources were available have been used to independently calculate the effect of SDD on the odds of developing Respiratory Tract Infection (RTI) and mortality, using the fixed effect model.

Results:

The three meta-analyses are summarized below for RTI (panel A) and mortality (panel 13).

(panel A) Source Events/Pts OR 95%CI ADP 702/3142 0.45 0.38-0.53 ADS 694/3377 0.41 0.35-0.49 IPD 638/3263 0.41 0.34-0.49 (panel B) Source Events/Pts OR 95%CI ADP 762/3142 0.87 0.74-1.03 ADS 975/3564 0.92 0.80-1.08 IPD 829/3357 0.89 0.76-1.05

Discussion:

Despite its advantages, the amount of resources required by IPM and its dependence on time and willingness of investigators to collaborate should not be overlooked. While exclusions after randomization emerged as a limiting factor to the use of meta-analyses based on ADP, ADS can be considered a valid and cheaper alternative to IPD, at least when categorical data are used and time dependent censoring is not relevant.