Thesis (MNutr (Human Nutrition))--Stellenbosch University, 2008. / Background
Critical illness is associated with increased production of reactive oxygen species
and oxidative stress, and low levels of most micronutrients with resultant diminished
endogenous antioxidant defences. Micronutrient supplementation is thought to be
beneficial to the critically ill patient by ameliorating oxidative stress and by improving
clinical outcome.
Objectives
This systematic review assessed the effects of micronutrient supplementation on
adults recovering from critical illness. Primary outcomes included clinical endpoints
[mortality, infectious complications, length of intensive care unit and hospital stay
(LICU and LOS)]. Secondary outcomes included descriptions of practice issues,
micronutrient status, morbidity, course of the acute phase response and oxidative
stress.
Search strategy
An electronic bibliographic database search was carried out, bibliographies of
retrieved articles were reviewed and personal files searched to obtain additional
citations. Databases were searched from inception until 29 February 2008.
Selection criteria
Randomized controlled trials (RCTs) of micronutrient supplementation (by any route)
in adult critically ill patients, given in addition to their routine care, were included.
Data collection and analysis
Two authors independently extracted data and assessed trial quality. For the primary
outcomes the random-effects model was used to estimate overall relative risk /
mean difference and effect size due to the presence of study heterogeneity.
Selected exploratory analyses were undertaken. Differences at the level of p<0.05
was considered to be statistically significant. The secondary outcomes were sparse
and variably recorded such that this data was not formally aggregated.
Main results
Fifteen RCTs involving 1714 participants and 18 RCTs involving 1849 participants were
included for the primary and secondary objectives respectively. The quality of the
RCTs, as reported, was disappointing, particularly for allocation concealment.
Fourteen trials (n=1468) of micronutrient supplementation showed a statistically significant reduction in overall mortality [relative risk (RR) 0.78, 95% confidence
interval (CI) 0.67-0.90, I2=0%, p=0.0009]. An asymmetrical funnel plot necessitates
caution when directly interpreting these results. Six RCTs (n=1194) indicated a
statistically significant reduction in 28 day mortality (RR 0.75, 95% CI 0.63-0.88, I2=0%,
p=0.0006) (symmetrical funnel plot). Micronutrient supplementation in this systematic
review was not associated with a reduction in infectious complications, LICU or LOS.
In sub-group analyses, single nutrients were associated with borderline statistical
significance (RR 0.82, 95% CI 0.66-1.01, I2=0%, p=0.06) in terms of mortality, whist a
sensitivity analysis of combined micronutrients indicated a significant reduction in
mortality (RR 0.69, 95% CI 0.54-0.90, I2=2%, p= 0.006). This review did not find clear
evidence that parenteral is superior to enteral administration in terms of clinical
outcomes. The secondary outcomes confirmed that timing, duration and dosing are
key factors to ensure optimal clinical benefit.
Conclusion
This review does suggest potential benefit of micronutrient supplementation in
critically ill adults for some clinical outcomes (especially mortality), but also highlights
that caution is warranted as nutrient interactions and risk of toxicity are not clearly
defined in critical illness. More large multi-centre randomized trials are necessary to
assess the effects of different types and doses of micronutrient supplementation in
selected groups of patients with different types of critical illness.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/2959 |
| Date | 12 1900 |
| Creators | Visser, Janicke |
| Contributors | Labadarios, D., Blaauw, R., Stellenbosch University. Faculty of Health Sciences. Dept. of Interdisciplinary Health Sciences. Human Nutrition. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Rights | Stellenbosch University |
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