Variable | Description | IRR | 95% CI | P-value |
---|---|---|---|---|
Year | 2006 | Referent | Â | Â |
 | 2007 | 1.12 | 0.73 – 1.72 | 0.607 |
 | 2008 | 0.89 | 0.57 – 1.39 | 0.611 |
 | 2009 | 1.63 | 1.08 – 2.46 | 0.021 |
 | 2010 | 2.62 | 1.76 – 3.89 | < 0.001 |
 | 2011 | 2.14 | 1.13 – 4.06 | 0.020 |
Month | January | Referent | Â | Â |
 | February | 1.09 | 0.70 – 1.71 | 0.689 |
 | March | 1.63 | 1.04 – 2.57 | 0.035 |
 | April | 1.88 | 1.22 – 2.91 | 0.005 |
 | May | 1.33 | 0.83 – 2.15 | 0.234 |
 | June | 0.89 | 0.53 – 1.51 | 0.664 |
 | July | 1.27 | 0.79 – 1.06 | 0.320 |
 | August | 1.44 | 0.92 – 2.26 | 0.111 |
 | September | 1.37 | 0.87 – 2.17 | 0.177 |
 | October | 1.33 | 0.84 – 2.10 | 0.221 |
 | November | 1.34 | 0.85 – 2.12 | 0.207 |
 | December | 1.42 | 0.91 – 2.23 | 0.122 |
Service | Medicine1 | Referent | Â | Â |
 | Surgery | 0.95 | 0.30 – 2.96 | 0.924 |
 | Other2 | 0.42 | 0.17 – 1.05 | 0.064 |