Advanced age | 2 positive studies [14, 27], 5 negative studies [12, 18, 22, 26, 28+] | Inconclusive: 1 large study in each side | 1 positive study [37], 4 negative studies [3, 41, 43§, 44] | Inconclusive: 1 large study found an association; another large study and four small studies did not |
Elevated APACHE score | 3 positive studies [12, 14, 18], 3 negative studies [17, 26, 27ƒ] | Large studies report a significant association | 1 positive study [3], 2 negative studies [43§, 44] | Inconclusive: studies with small sample size |
Histology showing diffuse alveolar damage# | 3 studies [12, 13, 21] | Small studies report high mortality in the univariate analysis; not enough data to assess for an association | 3 studies [29, 31, 34] | Small studies report high mortality in the univariate analysis; not enough data to assess for an association |
Hypoxaemia | 3 positive studies [14, 22##, 27¶¶], 1 negative study [18ƒ] | Large studies report a significant association | 3 negative studies [41+, 43§, 44] | No association was found; 2 studies with <20 patients each |
Mechanical ventilation¶ | 6 positive studies [12, 14++, 17, 18, 26, 27], 2 negative studies [22, 28] | Multiple studies report high mortality in the univariate analysis; 6 studies report a significant association | | Multiple studies report high mortality in the univariate analysis; not enough data to assess for an association |
Steroids | 3 negative studies [14, 26§§, 28+] | No association was found in 3 studies; 1 reported use of steroids was a protective factor | 1 negative study [41] | Inconclusive: only 1 study with a small sample size is available |