Table 2 Internal validity of included studies
Study | Prospective design | Multicenter enrollment | Selection bias | Performance bias | Attrition bias | Detection bias | Multivariate adjustment for potential confounders |
|---|---|---|---|---|---|---|---|
Norikazu Masuda 2017 [7] | ● | ○ | B | C | B | C | none reported |
David Miles 2017 [8] | ● | ○ | A | A | B | A | probably adequate |
Christoph Rochlitz 2016 [20] | ● | ● | B | B | B | C | none reported |
Christoph Zielinski 2016 [13] | ● | ● | A | A | B | A | probably adequate |
A. Welt 2016 [17] | ● | ● | A | A | A | A | probably adequate |
O. Trédan 2016 [21] | ● | ● | B | C | B | C | none reported |
Denise A. Yardley 2015 [18] | ● | ○ | B | C | A | C | none reported |
Veronique Dieras 2015 [19] | ● | ● | B | C | A | C | none reported |
Hans-Joachim Luck 2015 [16] | ● | ○ | A | A | A | B | probably adequate |
S.W. Lam 2014 [14] | ● | ● | A | A | A | B | probably adequate |
Joseph Gligorov 2014 [15] | ● | ● | A | A | B | B | probably adequate |
Istvan Lang 2013 [12] | ● | ● | A | A | B | A | probably adequate |
Adam M. Brufsky 2011 [22] | ● | ● | A | B | A | A | probably adequate |
Miguel Martin 2011 [23] | ● | ● | A | B | A | B | probably adequate |
David W. Miles 2010 [9] | ● | ● | A | A | A | A | probably adequate |
Robert Gray 2009 [10] | ● | ● | A | A | A | A | probably adequate |