Twenty-six RCTs (n=2,473) were included in the review.
The authors stated that none of the included studies obtained a maximum quality score of 5 according to the Jadad scale.
Infectious complication rate: the authors stated that they were unable to find any significant effect on the rate of infectious complications, as most of the studies reported the incidence of infection at different locations instead of the overall ratio of infected individuals. No data were given in the report.
Wound infection: based on 15 RCTs, immunonutrition was associated with a significantly reduced likelihood of wound infection compared with the control (OR 0.46, 95% CI: 0.30, 0.69, P=0.003).
Intra-abdominal abscess: based on 6 RCTs, immunonutrition was associated with a significantly reduced likelihood of intra-abdominal abscess compared with the control (OR 0.26, 95% CI: 0.12, 0.58, P=0.0005).
Nosocomial pneumonia: based on 11 RCTs, immunonutrition was associated with a significantly reduced likelihood of nosocomial pneumonia compared with the control (OR 0.54, 95% CI: 0.35, 0.84, P=0.007).
Bacteraemia: based on 9 RCTs, immunonutrition was associated with a significantly reduced likelihood of bacteraemia compared with the control (OR 0.45, 95% CI: 0.29, 0.69, P=0.0002).
Urinary tract infections (UTIs): based on 10 RCTs, no statistically significant difference was shown between the immunonutrition and control groups on the occurrence of UTIs (OR 0.66, 95% CI: 0.43, 1.00, P=0.05).
Sepsis: based on 5 RCTs, no statistically significant difference was shown between the immunonutrition and control groups on the occurrence of sepsis (OR 0.45, 95% CI: 0.14, 1.45, P=0.18).
MODS and ARDS: no statistically significant difference was found between the immunonutrition and control groups on the incidence of MODS (1 RCT), while immunonutrition was associated with a significantly reduced likelihood of ARDS compared with the control (2 RCTs; OR 0.21, 95% CI: 0.09, 0.52, P=0.0007).
Mechanical ventilation duration: based on 7 RCTs, immunonutrition was associated with a significant reduction of 2.25 days (95% CI: -0.5, -3.9, P=0.009) of mechanical ventilation compared with the control.
Intensive care unit (ICU) and hospital length of stay: immunonutrition was associated with mean reductions of 1.6 days (95% CI: -1.2, -1.9, P<0.0001) and 3.4 days (95% CI: 2.7, 4.0, P<0.0001), respectively in ICU (8 RCTs) and hospital (12 RCTs) length of stay. There was evidence of statistical heterogeneity.
Mortality: based on 18 RCTs, no statistically significant difference was shown between the immunonutrition and control groups on in-hospital mortality (OR 1.1, 95% CI: 0.54, 1.42, P=0.5). A subgroup analysis according to patient population did not find a significant effect on mortality. There was no evidence of statistical heterogeneity for either the overall analysis or the subgroup analyses.