Table 2. Specific characteristics of studies included in the review.

Author	Placebo controlled trial	Provided sources of unit costs in each country	Currency used
			Pounds	Euro	US dollar	Other
Canoui-Piotrine et al 2009 [25]	✗	✗		✓
Glasziou et al 2010 [26]	✓	✗				✓
Marcoff et al 2009 [27]	✗	✗			✓
Mittman et al 2009 [28]	✗	✗			✓
Reed et al 2004 [29]	✓	✗			✓
Simon et al 2006 [31]	✓	✗			✓
Lubell et al 2009 [32]	✗	✗			✓
Sullivan et al. 2003 [33]	✗	✗			✓
Briggs et al 2006 [34]	✗	✗	✓
Briggs et al 2010 [35]	✓	✗			✓
Lofdal et al 2005 [36]	✓	✗		✓
Bachert et al 2007 [37]	✓	✓		✓
Canonica et al 2007 [38]	✓	✓		✓
Fernandez et al 2005 [39]	✗	✗		✓
Manca et al 2003 [40]	✗	✗	✓
Garry et al. 2004 [41]	✗	✗	✓
Nasser et al. 2008 [42]	✓	✗	✓
Bracco et al 2007 [43]	✓	✗		✓
Knapp et al 2008 [44]	✗	✗	✓
Buxton et al 2004 [46]	✓	✓			✓
Rutten Von Molken et al 2007 [47]	✓	✗		✓
Willan et al 2006 [48]	✓	✓	✓			✓
Ra✓deva et al 2005 [49]	✗	✗			✓
Edbrooke et al 2011 [50]	✗	✗		✓
Lamy et al 2004 [51]	✓	✗	✓	✓	✓	✓
Drummond et al 2003 [52]	✗	✗		✓
Gomes et al. 2010 [53]	✗	✗	✓
Lorgelly et al 2010 [55]	✗	✗	✓
Price et al 2002 [57]	✗	✗	✓
Weintraub et al 2005 [58]	✓	✗			✓
Wade et al 2008 [59]	✗	✗	✓
Kolm 2007 [60]	✓	✗			✓
Jowett et al 2009 [61]	✗	✗		✓
Dukhovny et al 2011 [62]	✓	✗			✓
Annemans et al 2003 [81]	✗	✗		✓
Aspelin et al 2005 [82]	✗	✗		✓
Bakhai et al. 2003 [83]	✗	✗			✓
Brown et al. 2003 [84]	✗	✗				✓
Janzon et al 2003[85]	✓	✗	✓			✓
Lamy et al 2003 [86]	✓	✗			✓
Lindgren et al. 2005 [87]	✗	✗		✓
Martin et al 2003 [88]	✓	✗	✓
Reed et al. 2004 [89]	✓	✗			✓
Welsch et al 2009 [90]	✓	✗			✓