Table 1. Characteristics of included studies of meta-analysis.
| Author (year) | Sample size | Mean age, y | Male sex, % | Treatment arms (No.) | Timing from admission/injury to starting of nutrition | Initial GCS | Primary outcomes | Nutritional outcomes | Quality score# |
| Rapp (1983) | 38 | 40 | NA | Early PN (20) vs Delayed EN (18) | Early: within 48 hours after admission; delayed: till the bowel sounds were present and the gastric residual volume was less than 100 ml/hour | Mean: 7.5 | Mortality; GOS | Nitrogen balance; nitrogen intake; caloric intake; nitrogen excretion; serum albumin level; serum transferrin values; lymphocyte count; serum glucose levels | R1B0A1 = 2 |
| Hadley (1986) | 45 | 28 | 88.9 | Early PN (24) vs Early EN (21) | Within 48 hours of admission | ≤10 (mean: 5.8) | Infection rate; GCS; mortality | Nitrogen loss; nitrogen intake; nitrogen balance; nitrogen excretion; serum albumin levels; weight loss | R0B0A1 = 1 |
| Young (1987) | 51 | 33 | 82.4 | Early PN (23) vs Delayed EN (28) | Early: within 48 hours postinjury; delayed: till the termination of low wall suction | 4–10 | GOS; mortality; complication rate | Nitrogen balance; caloric balance; nitrogen intake; lymphocyte counts; albumin levels | R1B0A1 = 2 |
| Grahm (1989) | 32 | 27 | 90.6 | Early jejunal (17) vs Delayed gastric (15) | Nasojejunal: within 36 hours of admission; gastric: after day 3 when gastric function returned | ≤10 | Infection rate; length of ICU stay | Nitrogen balance; caloric intake; nitrogen intake | R0B0A0 = 0 |
| Borzotta (1994) | 49 | 27 | 81.6 | Early PN (21) vs Early EN (28) | Within 72 hours of injury | 3–8 | Complication rate | Measured resting energy expenditure; nitrogen balance; nutrition excretion | R1BOA0 = 1 |
| Minard (2000) | 27 | 33 | 70.4 | Early EN (12) vs Delayed EN (15) | Early: within 60 hours of injury; delayed: when the gastroparesis resolved | 3–11 | Mortality; LOS in ICU and hospital; ventilator days; complication rate | Caloric intake | R1B0A1 = 2 |
| Falcan (2004) | 20 | 27 | 95 | Early EN (10) vs Early EN with glutamine and probiotics (10) | Within 48 hours of admission | Mean: 7 | Infection rate; LOS in ICU; period of mechanical ventilation | Nitrogen balance; caloric intake; protein intake | R1B0A1 = 2 |
| Kostadima (2005) | 41 | 47 | 78 | Gastrostomy (20) vs Nasogastric tube (21) | Within 24 hours of intubation | <6 | Incidence of VAP; length of stay in ICU; duration of mechanical ventilation; mortality | NA | R1B0A1 = 2 |
| Briassoulis (2006) | 40 | 10 | NA | Immune enhancing diet (20) vs Regular formula (20) | Within 12 hours of admission | Mean: 6.2 | Rate of nosocomial infections; LOS; length of mechanical ventilation; mortality | Cytokines concentrations; nitrogen balance | R2B1A1 = 4 |
| Hartl (2008) | 797 | ≥16 | NA | Early nutrition (755) vs Delayed nutrition (42) | Early: within 7 days postinjury; delayed: after 7 days postinjury | 3–8 | Mortality | NA | S4C202 = 8 |
| Khorana (2009) | 40 | 41 | 80 | Standard EN (20) vs Immunonutrient containing EN (20) | Within the first 24 hour after operation | 5–10 | Complication rate; LOS in ICU | IL-6 and IL-10 levels | R2B2A1 = 5 |
| Acosta-Escribano (2010) | 104 | 38 | 86 | Transpyloric feeding (50) vs Gastric feeding (54) | Within the first 24 hour after admission | Mean: 6 | Incidence of VAP; GI complications; length of stay in ICU and hospital; mortality | Efficacious volume of diet | R1B0A1 = 2 |
| Justo Meirelles (2011) | 22 | 31 | 90.9 | Early PN (10) vs Early EN (12) | Early after admission when hemodynamically stable | 9–12 | Mortality; complication rate; LOS in ICU | Calories intake; nitrogen intake; nitrogen balance; urinary nitrogen loss; serum glucose; CRP; albumin | R1B0A1 = 2 |
| Chourdakis (2011)† | 59 | 35 | 79.7 | Early EN (34) vs Delayed EN (25) | Early: Within 24–48 hours after injury; delayed: when the gastroparesis resolved (48 h-5d) | ≥9 | Mortality rate; complication rate; LOS in ICU | TSH, FT3, FT4, cortisol, and testosterone levels | R1B0A1 = 2 |
| Chiang (2012)† | 297 | 0–99 | 72.4 | EN (145) vs Non-EN (152) | Early: within 48 hours postinjury; delayed: no feeding formula added for 7 days | 4–8 | GOS; mortality; LOS in ICU | NA | S4C202 = 8 |
| Dhandapani (2012)† | 95 | 35 | NA | Early EN (64) vs Delayed EN (31) | Early: within 7 days postinjury; Delayed: after 7 days postinjury | 4–8 | GOS | Anthropometric measurements (mid-arm circumference; triceps skin fold thickness); serum albumin levels; urinary creatinine levels; incidence of malnutrition | S4C2O2 = 8 |
†
Non-randomized prospective studies.
#
Jadad score for RCTs: randomization (R0-2), blinding (B0-2) and attrition information (A0-1); Newcastle-Ottawa Scale (NOS) for cohort studies: selection (S0-4), comparability (C0-2), outcome (O0-3).
Abbreviations: EN, enteral nutrition; GCS, Glasgow Coma Scale; GOS, Glasgow Outcome Score; LOS, length of stay; NA, not available; NNG, non-nasogastric feeding; NG, nasogastric feeding; PN, parenteral nutrition; vs, versus; VAP, ventilator-associated pneumonia.