Table 1.
Summary of included studies
| Paper | Country | Study design | Years included | Quality rating |
|---|---|---|---|---|
| Bardsey 2010 [41] | UK | Cross-sectional secondary analysis of administrative data | 2006–08 | Poor |
| Damiani 2009 [29] | Italy | Cross-sectional secondary analysis of administrative data | 2004 | Poor |
| Fernandez 2008 [36] | UK | Cross-sectional secondary analysis of administrative data | 1998–2000 | Good |
| Forder 2009 [35] | UK | Cross-sectional secondary analysis of administrative data | 2004–05 | Good |
| Gaughan 2013 [30] | UK | Cross-sectional secondary analysis of administrative data | 2008–09 | Good |
| Gaughan 2015 [31, 40] | UK | Cross-sectional secondary analysis of administrative data | 2009–13 | Good |
| Herrin 2015 [37] | US | Cross-sectional secondary analysis of administrative data | 2007–10 | Good |
| Holmås 2014 [38] | Norway | Cross-sectional secondary analysis of administrative data | 2007–09 | Fair |
| Hunold 2014 [39] | US | Cross-sectional secondary analysis of administrative data | 2010 | Good |
| Imison 2012 [32] | UK | Cross-sectional secondary analysis of administrative data | 2009–10 | Poor |
| Liotta 2012 [33] | Italy | Cross-sectional secondary analysis of administrative data | 2006 | Poor |
| Reeves 2004 [34] | UK | Cross-sectional secondary analysis of administrative data | 2000 | Good |