Recent military fatalities in Afghanistan: change to 10-weekly reporting

Clive Fairweather and I have reported 20-weekly on a) military fatalities in Afghanistan by cause, and b) fatality rate per 1000-personnel years by nation since 1 May 2006. Prior to 1 May 2006, UK military fatalities in Afghanistan since 2001 had been seven only -  five non-hostile deaths, one by hostile fire, and one by a suicide bomber.

We have now changed our regular reporting cycle: to 10-weekly from 22 February 2010. The first of these regular 10-weekly reports was for the period 22 February to 2 May 2010, in the run-up to the General Election. But the principal reason for the change to ten-week reporting was that the UK's  military fatalities in Afghanistan exceeded 32 per 20-weeks.
The reasons for the high numbers of fatalities are two-fold: i) deployment of more UK troops – see Table, up from 4,500 in Period 1 to at least 10,000 currently - and ii) higher fatality rate per 1000-personnel years. UK military fatality rates in Afghanistan from 1 May 2006 to 2 May 2010 have been as follows:
PERIODS 1+2+3+4:  8.9 per 1,000 pys (95%CI:   7 to 11, based on 76 fatalities in 8,580 pys)
PERIODS 5+6+7+8:   6.5 per 1,000 pys (95%CI:   5 to  8, based on 77 fatalities in 11,896 pys)
PERIODS 9+10+11a:13.6 per 1,000 pys (95%CI: 11 to 16, based on 123 fatalities in 9,039 pys).
Analytically, we characterise major combat as 6 fatalities per 1,000 personnel-years. Thus, it is clear that UK troops have faced major combat (and worse) throughout the past four years in Afghanistan.
The number of fatal Improvised Explosive Device (IED) incidents in Afghanistan has escalated twice – firstly, from PERIOD 4 (which began on 25 June 2007: up from 12 in PERIOD 3 to 27 fatal IED incidents, which caused 22 and 44 coalition deaths respectively). The second escalation was from PERIOD 9 (which began on 18 May 2009: up from 34 in PERIOD 8 to 94 fatal IED incidents, which caused 55 and 136 coalition deaths respectively).
In PERIOD 11b, which ends on 11 July 2010, we shall be better able to compare UK and US military fatalities rates in the same province, Helmand, as US has had 20,000 troops deployed there throughout PERIOD 11b.

Sheila M. Bird is at the  MRC Biostatistics Unit, CAMBRIDGE CB2 0SR