Table 2.

Characteristics of studies associated with favourable incremental cost effectiveness ratios according to three threshold values. Values are odds ratios (95% confidence intervals)

Study characteristic	Crude OR (95% Cl)			Adjusted OR (95% Cl)*
	<$20 000/QALY	<$50 000/QALY	<$100 000/QALY	<$20 000/QALY	<$50 000/QALY	<$100 000/QALY
Publication year
1976-91	1.6 (0.98 to 2.7)	1.4 (0.80 to 2.4)	1.2 (0.67 to 2.3)	1.6 (0.96 to 2.7)	1.3 (0.76 to 2.3)	1.2 (0.61 to 2.2)
1992-6	1.3 (0.94 to 1.9)	1.4 (0.93 to 2.3)	1.1 (0.68 to 1.6)	1.3 (0.87 to 1.8)	1.3 (0.87 to 1.9)	1.0 (0.64 to 1.6)
1997-2001	1.0	1.0	1.0	1.0	1.0	1.0
Journal impact factor†
<2	1.0	1.0	1.0	1.0	1.0	1.0
2-4	0.62 (0.42 to 0.91)	0.62 (0.41 to 0.94)	0.59 (0.38 to 0.94)	0.75 (0.50 to 1.1)	0.82 (0.53 to 1.3)	0.77 (0.47 to 1.2)
>4	0.60 (0.42 to 0.86)	0.56 (0.38 to 0.82)	0.83 (0.53 to 1.3)	0.95 (0.63 to 1.4)	0.81 (0.52 to 1.3)	1.1 (0.66 to 1.9)
Disease category
Cardiovascular	1.0	1.0	1.0	1.0	1.0	1.0
Endocrine	1.3 (0.68 to 2.6)	1.2 (0.58 to 2.5)	1.3 (0.58 to 3.0)	1.2 (0.56 to 2.4)	1.1 (0.52 to 2.3)	1.2 (0.53 to 2.7)
Infectious	1.1 (0.66 to 1.7)	0.79 (0.48 to 1.3)	0.74 (0.43 to 1.3)	1.0 (0.64 to 1.7)	0.75 (0.44 to 1.3)	0.71 (0.39 to 1.3)
Musculoskeletal	1.4 (0.60 to 3.3)	1.3 (0.51 to 3.1)	1.4 (0.50 to 3.7)	1.1 (0.43 to 2.7)	0.89 (0.34 to 2.3)	1.1 (0.37 to 3.1)
Neoplastic	0.91 (0.56 to 1.5)	0.79 (0.46 to 1.3)	0.77 (0.42 to 1.4)	0.78 (0.47 to 1.3)	0.64 (0.37 to 1.1)	0.69 (0.36 to 1.3)
Neurological/psychiatric	0.76 (0.40 to 1.5)	0.78 (0.40 to 1.5))	0.66 (0.31 to 1.4)	0.75 (0.39 to 1.4)	0.70 (0.34 to 1.4)	0.61 (0.27 to 1.4)
Other	1.2 (0.75 to 1.8)	0.67 (0.42 to 1.1)	0.52 (0.31 to 0.88)	1.0 (0.63 to 1.6)	0.53 (0.31 to 0.88)	0.49 (0.27 to 0.86)
Study funding source‡
Non-industry	1.0	1.0	1.0	1.0	1.0	1.0
Industry	2.2 (1.4 to 3.4)	3.5 (2.0 to 6.1)	3.4 (1.6 to 7.0)	2.1 (1.3 to 3.3)	3.2 (1.8 to 5.7)	3.3 (1.6 to 6.8)
Not specified	1.3 (0.95 to 1.9)	1.5 (1.1 to 2.2)	1.4 (0.93 to 2.1)	1.3 (0.89 to 1.8)	1.5 (1.0 to 2.1)	1.5 (0.97 to 2.2)
Region of study
Europe	0.50 (0.28 to 0.89)	0.43 (0.21 to 0.87)	0.46 (0.21 to 1.0)	0.59 (0.33 to 1.1)	0.42 (0.21 to 0.86)	0.43 (0.19 to 0.96)
United States	0.35 (0.21 to 0.57)	0.29 (0.16 to 0.55)	0.33 (0.16 to 0.66)	0.44 (0.26 to 0.76)	0.35 (0.18 to 0.67)	0.33 (0.16 to 0.68)
Other§	1.0	1.0	1.0	1.0	1.0	1.0
Methodological quality¶
1.0-4.0	1.0	1.0	1.0	1.0	1.0	1.0
4.5-5.0	0.92 (0.64 to 1.3)	0.95 (0.64 to 1.4)	0.96 (0.62 to 1.5)	1.0 (0.70 to 1.5)	1.1 (0.70 to 1.6)	1.0 (0.63 to 1.6)
5.5-7.0	0.48 (0.33 to 0.70)	0.57 (0.39 to 0.83)	0.82 (0.52 to 1.3)	0.58 (0.37 to 0.91)	0.72 (0.45 to 1.2)	0.90 (0.51 to 1.6)

QALY, quality adjusted life year.

^*Adjusted for all other study characteristics.

^†Impact factor in the year before publication.

^‡Funding by a pharmaceutical or medical device manufacturer.

^§Canada 41 (59%), Australia 18 (26%), Japan 2 (3%), New Zealand 2 (3%), South Africa 2 (3%), other 5 (7%).

^¶Mean score from two reviewers.