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Table 1 Description of the included trials

From: Vitamin C may reduce the duration of mechanical ventilation in critically ill patients: a meta-regression analysis

Trial [ref.] N Setting Vitamin C Length of mechanical ventilation (hours) RoM
Route Dose (g/day) Vitamin C Control  
   Mean SD Mean SD  
Bjordahl et al. [11] 185 Cardiac po 2 28.8 19.2 33.6 24.0 0.86
Amini et al. [12] 137 Cardiac po 3 7.3 6.0 6.7 4.3 1.10
Dehghani et al .[13] 100 Cardiac po 1 13.4 2.0 15.4 14.3 0.87
Habib et al. [14] 100 Sepsis iv 6 110 50 189 72 0.58
Safaei et al. [15] 58 Cardiac iv 2 15.1 5.39 22.9 20.46 0.66
Ebade et al. [16] 40 Cardiac iv 3 2.04 0.35 1.99 0.31 1.02
Tanaka et al. [17] 37 Burns iv 90* 290 211 511 374 0.57
Zabet et al. [18] 28 Sepsis iv 6* 36.6 16.1 46.8 10.1 0.78
Sadeghpour et al. [19]** 290 Cardiac po 1 11.8 3.9 14.1 9.5 0.84
  1. The trials are listed by the number of patients (N). The mean age in the trials ranged from 42 to 64 years, with a median of 60 years. The proportion of males varied from 58% to 75%. Five trials were carried out in Iran [12, 13, 15, 18, 19], two in Egypt [14, 16], one in the USA [11], and one in Japan [17]. For detailed descriptions of the trials, see Additional file 1: Table S1. The Amini trial [12] results are modified as described previously [1]
  2. *Estimated vitamin C dose, see the “Methods” section
  3. **Sadeghpour et al. [19] recruited 500 participants but reported the results for just 290 participants [1]. Because of the high dropout rate (42%), we did not include this trial in our calculations, but we overlay the findings in Fig. 4
  4. iv intravenous, po per oral, RoM ratio of means [22]: e.g., for the Bjordahl trial [11], RoM = 0.86, based on 28.8/33.6, and RoM = 0.86 indicates that ventilation time in the vitamin C group was 14% shorter than in the placebo group