Table 1

Description of the data: events during index period, control periods and total

Index period*Control period IControl period IIControl periods I and IITotal
Number of events157470120590747
Number of days5924262304363
Mean events/day (95% CI)2.66 (2.19 to 3.13)1.94 (1.77 to 2.12)1.94 (1.60 to 2.27)1.94 (1.78 to 2.10)2.06 (1.91 to 2.21)
SD1.801.401.331.381.48
Median events/day32222
Minimum/maximum0–80–60–60–60–8
  • * Index period: January and February 2007.

  • Control period I: December 2004 to March 2005 and December 2005 to March 2006.

  • Control period II: December 2006 and March 2007.