Selenium supplementation for critically ill adults.
BACKGROUND
Selenium is a trace mineral essential to human health, which has an important role in the immune response, defence against tissue damage and thyroid function. Improving selenium status could help protect against overwhelming tissue damage and infection in critically ill adults.


OBJECTIVE
This review assessed the effects of selenium supplementation including the selenium-containing compound, ebselen, on adults recovering from critical illness.


METHODS
We searched CENTRAL (The Cochrane Library, Issue 2, 2003), MEDLINE, (1966 to July 2003), EMBASE (1980 to Week 30 2003),CAB NAR (1973 to March 2003), BIOSIS (1985 to July 2003), CINAHL (1982 to July 2003), HEALTHSTAR (1975 to September 2002), Current Controlled Trials, and reference lists. We contacted investigators, and handsearched four journals. Date of the most recent search: December 2003.


METHODS
Randomized trials of selenium or ebselen supplementation by any route, in adults with critical illness (including burns, head injury, brain haemorrhage, cerebrovascular accident and surgery).


METHODS
Two reviewers independently extracted data and assessed trial quality. We sought additional information as required from trialists. We also undertook pooling of data for outcomes and selected exploratory analyses were undertaken.


RESULTS
Seven randomized trials involving813participants were included. The quality of trials, as reported, was poor, particularly for allocation concealment. The availability of outcome data was limited and trials involving selenium supplementation, were small. Thus the results must be interpreted with caution. Because of heterogeneity, results are presented for the random effects models. Four selenium trials showed no statistically significant difference in mortality (relative risk (RR) 0.52, 95% confidence interval (CI) 0.20 to 1.34). Three trials of ebselen also showed no statistically significant difference in mortality (RR 0.83, 95% CI 0.51 to 1.35). One trial of selenium found no statistically significant difference between groups for participants developing infection (RR 1.33, 95% CI 0.55 to 3.24). Three trials of ebselen provided data for participants developing infections (pyrexia, respiratory infections or meningitis), which was not statistically significant (RR 0.60, 95% CI 0.36 to 1.02). No clear evidence emerged for the benefits of selenium or ebselen supplementation for the outcomes of days on a ventilator, length of intensive care unit stay, length of hospital stay or quality of life.


CONCLUSIONS
There is insufficient evidence to recommend supplementation of critically ill patients with selenium or ebselen. Trials are required which overcome the defects of the reviewed studies, particularly inadequate size and methodology. This review will be updated when four ongoing trials are completed.
Avenell
A
A
Health Services Research Unit, University of Aberdeen, Polwarth Building, Foresterhill, Aberdeen, Scotland, UK, AB25 2ZD. a.avenell@abdn.ac.uk
Noble
D W
DW
Barr
J
J
Engelhardt
T
T
D000328:Adult; D000975:Antioxidants / Q000009:adverse effects / Q000627:therapeutic use*; D001393:Azoles / Q000009:adverse effects / Q000627:therapeutic use*; D016638:Critical Illness / Q000401:mortality / Q000628:therapy*; D019587:Dietary Supplements; D006801:Humans; D054833:Isoindoles; D016566:Organoselenium Compounds / Q000009:adverse effects / Q000627:therapeutic use*; D016032:Randomized Controlled Trials as Topic; D012643:Selenium / Q000009:adverse effects / Q000627:therapeutic use*
D000975:Antioxidants; D001393:Azoles; D054833:Isoindoles; D016566:Organoselenium Compounds; C042986:ebselen; D012643:Selenium