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Table 1 The main characteristics of the studies included

From: Effects of different ascorbic acid doses on the mortality of critically ill patients: a meta-analysis

Author Year Design Patients(n intervention/n control) Ascorbic acid dose Other antioxidant Time of treatment initiation Duration of treatment Mortality at final follow-up (N intervention/N control) Other clinical parameters
Ferrón-Celma 2009 RCT Undergoing abdominal surgery and postoperative mortality risk > 30% (10/10) 450 mg/d None 12 h post-surgery From 12 h post-surgery to d6 post-surgery 6 days: 6/4 Caspase-3↓, PARP proteins↓ and Bcl-2 levels ↑in treatment group
Fowler III 2014 RCT Severe sepsis (16: high dose 8 and low dose 8)/8 50 or 200 mg/kg/d None 2–4 h following randomization 96 h 28 days: 7(low dose: 3, high dose 4)/5 SOFA scores↓(high dose was the most remarkable); CRP ↓in treatment group; PCT↓ only in the high-dose group; The TM↑ in control group, while treatment group remained the same.
Zabet 2016 RCT Post-operation patients with septic shock and need a vasopressor (14/14) 25 mg/kg q6 h None Unavailable 72 h 28 days: 2/9 Less vasopressor
Kahn 2011 Observational Burn covering greater than 20% of TBSA (17/16) 66 mg/kg/hr None At a mean time of 52 ± 26 min after admission Unavailable Hospital mortality: 4/3 Mean PaO2/FiO2 during the study period: ascorbic acid group: 201.32 ± 32.22; control group: 221.23 ± 13.87
Tanaka 2000 Quasi-RCT Burn covering greater than 30% of TBSA (19/18) 66 mg/kg/h None After admission The initial 24-h Hospital mortality: 9/7 Edema ↓ body weight gain ↓ in treatment group
Lin 2018 Observational During burn shock resuscitation (38/42) 66 mg/kg/h None Mean time: 4.01 ± 15 h Unavailable Hospital mortality: 10/10 Acute renal failure↑ in high-dose group
Marik 2017 Observational Severe sepsis or septic shock and a PCT level ≥ 2 ng/ml (47/47) 1.5 g q6 h None Unavailable 4 days Hospital mortality: 4/19 The median 72-h PCT ↓,the 72-h SOFA score ↓in treatment group
Razmkon 2011 RCT GCS ≤ 8 with diffuse axonal injury(49/27) 500 mg/d or 10 g/d None Within 24 h 7 days Hospital mortality: 14 (low dose: 7, high dose: 7)/8 No promise for short- and long-term neurological outcome in treatment group
Sandesc 2017 Observational Injury severity score > 16(35/32) 3000 mg/d N-Acetylcysteine 1200 mg/d Unavailable Unavailable Hospital mortality: 5/11 Possibility to develop into Sepsis or MODS↓;at discharge/until death the APACHE II score ↓
Palli 2017 RCT Needs for contrast-enhanced CT(60/64) 2 g/d N-Acetylcysteine 1200 mg/d 2 h before and at 10 and 18 h after contrast agent 18 h Hospital mortality: 15/11 Failed to reduce the incidence of CIN;
Galley 1997 Quasi-RCT Septic shock and need a vasopressor(16/14) 1 g/d N-Acetylcysteine and vitamin E Unavailable Unavailable Hospital mortality: 11/8 Beneficial hemodynamic changes.
Nathens 2002 RCT Undergoing general surgery/trauma (301/294) 1000 mg q8 h α-Tocopherol 1000 IU q8 h At a mean time of 11.3 ± 6 h 28 days 28 days: 4/7 Multiple organ failure↓, concentrations of TNF-α, IL-1β, IL-6↓, ICU and hospital stay ↓,ventilator-free days ↑ in treatment group.
  1. A quasi-RCT uses quasi-random method of allocating participants to different interventions, such as allocation by date of birth, day of the week, medical record number, month of the year, or the order in which participants are included in the study