Final agreed methodological quality assessment results for all included studies*
| Author | Year | Question 1 | Question 2 | Question 3 | Question 4 | Question 5 | Question 6 | Question 7 | Question 8 | Question 9 | Question 10 | Total score† | Quality category‡ |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| All-cause | |||||||||||||
| Antonopoulos32 | 2005 | 0 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 1 | 1 | 6 | Moderate |
| Currie24 | 1998 | 1 | 0 | 0 | 1 | 0 | 0 | 1 | 0 | 1 | 1 | 5 | Moderate |
| Donnan33 | 2000 | 1 | 0 | 0 | 1 | 0 | 0 | 1 | 0 | 1 | 1 | 5 | Moderate |
| Gottrup34 | 2013 | 1 | 1 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 3 | Poor |
| Gruen35 | 1997 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 0 | 0 | 1 | 6 | Moderate |
| Henke36 | 2005 | 1 | 0 | 0 | 1 | 0 | 0 | 1 | 0 | 1 | 0 | 4 | Moderate |
| Lacroix37 | 2008 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 8 | Good |
| Morgan38 | 2010 | 1 | 0 | 0 | 1 | 0 | 0 | 1 | 0 | 1 | 1 | 5 | Moderate |
| Diabetes-related | |||||||||||||
| Ajayi39 | 2009 | 0 | 0 | 0 | 1 | 0 | 0 | 1 | 0 | 0 | 1 | 3 | Poor |
| Asumanu40 | 2010 | 0 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 1 | 0 | 5 | Moderate |
| Chijioke41 | 2010 | 0 | 0 | 0 | 1 | 0 | 0 | 1 | 0 | 1 | 0 | 3 | Poor |
| Daultry42 | 2011 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 4 | Moderate |
| Hurd43 | 2009 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 0 | 0 | 6 | Moderate |
| Leichter44 | 1982 | 0 | 0 | 0 | 1 | 0 | 0 | 1 | 0 | 0 | 0 | 2 | Poor |
| Mahe45 | 2006 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 0 | 0 | 1 | 6 | Moderate |
| Masson46 | 1992 | 1 | 1 | 0 | 1 | 0 | 0 | 1 | 0 | 0 | 0 | 4 | Moderate |
| Mohammad Akther47 | 2011 | 0 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 1 | 0 | 5 | Moderate |
| Mottini48 | 2003 | 0 | 0 | 0 | 1 | 0 | 0 | 1 | 0 | 0 | 0 | 2 | Poor |
| Nason49 | 2013 | 1 | 0 | 0 | 1 | 0 | 0 | 1 | 0 | 0 | 0 | 3 | Poor |
| Ogbera50 | 2006 | 1 | 0 | 0 | 1 | 0 | 0 | 1 | 0 | 0 | 0 | 3 | Poor |
| Ogbera51 | 2007 | 0 | 1 | 0 | 1 | 0 | 0 | 1 | 0 | 0 | 1 | 4 | Moderate |
| Otu52 | 2013 | 0 | 0 | 0 | 1 | 1 | 0 | 1 | 0 | 1 | 0 | 4 | Moderate |
| Sjoberg53 | 2007 | 0 | 0 | 0 | 1 | 0 | 0 | 1 | 0 | 0 | 1 | 3 | Poor |
| Tait54 | 2007 | 1 | 1 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 3 | Poor |
| Unachukwu55 | 2007 | 0 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 4 | Moderate |
| Wallymahmed56 | 2005 | 1 | 1 | 0 | 1 | 0 | 0 | 1 | 0 | 0 | 0 | 4 | Moderate |
| Williams57 | 1985 | 1 | 0 | 0 | 1 | 0 | 0 | 1 | 0 | 0 | 0 | 3 | Poor |
| Pressure ulcer-related | |||||||||||||
| Alja’afreh58 | 2013 | 0 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2 | Poor |
| Allcock59 | 1994 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 0 | 0 | 0 | 5 | Moderate |
| Amlung60 | 2001 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 5 | Moderate |
| Barczak61 | 1997 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 1 | 6 | Moderate |
| Barrois62 | 1995 | 1 | 1 | 0 | 1 | 1 | 0 | 0 | 0 | 0 | 1 | 5 | Moderate |
| Barrois63 | 2008 | 1 | 1 | 0 | 1 | 1 | 0 | 1 | 0 | 1 | 1 | 7 | Good |
| Bours64 | 1999 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 1 | 7 | Good |
| Bours65 | 2002 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 1 | 7 | Good |
| Brito66 | 2013 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 1 | 6 | Moderate |
| Charlier67 | 2001 | 1 | 1 | 1 | 0 | 0 | 0 | 1 | 0 | 0 | 1 | 5 | Moderate |
| Clark68 | 1992 | 1 | 1 | 0 | 1 | 1 | 0 | 1 | 0 | 0 | 0 | 5 | Moderate |
| Cole69 | 2004 | 1 | 1 | 1 | 0 | 1 | 0 | 1 | 0 | 0 | 0 | 5 | Moderate |
| da Silva Cardoso70 | 2010 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 5 | Moderate |
| Dealey71 | 1991 | 1 | 1 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 3 | Poor |
| Dealey72 | 1994 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 0 | 0 | 6 | Moderate |
| Ek73 | 1982 | 1 | 1 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 3 | Poor |
| Gallagher74 | 2008 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 8 | Good |
| Galvan-Martinez75 | 2012 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 0 | 1 | 7 | Good |
| Gawron76 | 1994 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 8 | Good |
| Gethin77 | 2005 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 0 | 1 | 7 | Good |
| Gosnell78 | 1992 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 8 | Good |
| Groeneveld79 | 2004 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 8 | Good |
| Gunningberg80 | 2005 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 8 | Good |
| Gunningberg81 | 2006 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 8 | Good |
| Gunningberg82 | 2008 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 8 | Good |
| Gunningberg83 | 2013 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 1 | 6 | Moderate |
| Hopkins84 | 2000 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 5 | Moderate |
| House85 | 2011 | 1 | 1 | 1 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 4 | Moderate |
| Inan86 | 2012 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 1 | 1 | 8 | Good |
| Jenkins87 | 2010 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 5 | Moderate |
| Lahmann88 | 2006 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 0 | 1 | 7 | Good |
| Langemo89 | 1990 | 1 | 1 | 1 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 4 | Moderate |
| Lepisto90 | 2001 | 1 | 1 | 1 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 4 | Moderate |
| Meehan91 | 1990 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 1 | 0 | 6 | Moderate |
| Meehan92 | 1994 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 1 | 0 | 6 | Moderate |
| Nyquist93 | 1987 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 5 | Moderate |
| O’Brien94 | 1998 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 5 | Moderate |
| Pearson95 | 2000 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 0 | 0 | 6 | Moderate |
| Soldevilla96 | 2006 | 1 | 1 | 0 | 1 | 1 | 0 | 1 | 0 | 0 | 0 | 5 | Moderate |
| Thoroddsen97 | 1999 | 0 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 6 | Moderate |
| Tubaishat98 | 2011 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 8 | Good |
| Tubaishat99 | 2013 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 0 | 1 | 7 | Good |
| Uzun100 | 2007 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 1 | 1 | 8 | Good |
| Vanderwee101 | 2007 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 1 | 7 | Good |
| Vanderwee102 | 2011 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 8 | Good |
| Vangilder4 | 2008 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 1 | 1 | 7 | Good |
| Vangilder103 | 2010 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 1 | 1 | 7 | Good |
| Wann-Hansson104 | 2008 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 1 | 1 | 8 | Good |
| Whittington105 | 2004 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 4 | Moderate |
| Young106 | 2002 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 8 | Good |
| Zhao107 | 2010 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 0 | 1 | 7 | Good |
| Total (n) | 65 | 65 | 53 | 69 | 52 | 17 | 46 | 0 | 20 | 39 | 426 | ||
| Total (%) | 83.3 | 83.3 | 67.9 | 88.5 | 66.7 | 21.8 | 60.0 | 0 | 25.6 | 50.0 | 54.6 | ||
*Please see online supplementary table S3 for descriptions of each question; score: 1, ‘yes’; 0, ‘no’ or ‘not reported’.
†Total score, total agreed study quality score from the methodological assessment performed (total possible score is 10).
‡Quality category, total study quality score was classified as either ‘poor’ (total score=0–3), ‘moderate’ (total score=4–6) or ‘good’ (total score=7–10) study quality score.
Author, primary author of included study; Year, year included study was published.