Critique of the ARDSNetwork Experimental Design, Implementation, and Reporting

John H. Noble, Jr., Ph.D
AHRP Board Member

Table 1. Theoretical Distribution of Tidal Volume Changes, Pre- to Post- Random Assignment of 861 Patients Who Were Receiving Medical Care and Adjunctive Ventilator Therapy at 10 ARDSNet University Centers for ARDS-Precipitating Conditions and Their Complications, March 1996-March 1999
Pre-Value1 6 Minus Pre-Value2 Percent Change4 12 Minus Pre-Value3 Percent Change4
4.5 1.5 +33.3 7.5 +166.7
5.0 1.0 +20.0 7.0 +140.0
5.5 0.5 +9.1 6.5 +118.2
6.0 0 0 6.0

+100.0
6.5 -0.5 -7.7 5.5 +84.6
7.0 -1.0 -14.3 5.0 +71.4
7.5 -1.5 -20.0 4.5 +60.0
8.0 -2.0 -25.0 4.0 +50.0
8.5 -2.5 -29.4 3.5 +41.2
9.0 -3.0 -33.3 3.0 +33.3
9.5 -3.5 -36.8 2.5 +26.3
10.0 -4.0 -40.0 2.0 +20.0
10.5 -4.5 -42.9 1.5 +14.3
11.0 -5.0 -45.5 1.0 +9.1
11.5 -5.5 -47.8 0.5 +4.4
12.0 -6.0 -50.0 0 0
12.5 -6.5 -52.0 -0.5 -4.0
13.0 -7.0 -53.9 -1.0 -7.7
13.5 -7.5 -55.6 -1.5 -11.1
14.0 -8.0 -57.1 -2.0 -14.3
14.5 -8.5 -58.6 -2.5 -17.2
15.0 -9.0 -60.0 -3.0 -20.0
15.5 -9.5 -61.3 -3.5 -22.6
16.0 -10.0 -62.5 -4.0 -25.0
16.5 -10.5 -63.6 -4.5 -27.3
17.0 -11.0 -64.7 -5.0 -29.4
17.5 -11.5 -65.7 -5.5 -31.4

1 Tidal volumes before ARDSNet randomization as reported by Eichacker, Banks, & Natanson (2003).

2 Possible difference in tidal volume value associated with the corresponding pre-randomization value after randomization into ARDSNet low (6 mL per kg. PBW) experimental group.

3 Possible difference in tidal volume value associated with the corresponding pre-randomization value after randomization into ARDSNet high (12 mL per kg. PBW) experimental group.

4 Possible post- minus pre-randomization tidal volume difference divided by pre-randomization tidal volume.

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