Factors explaining the heterogeneity of effects of patient decision aids on knowledge of outcome probabilities: a systematic review sub-analysis

Table 1 Study-level covariate values, observed effect size measures and pooled heterogeneity estimates listed in order of increasing relative risk

Study	Type of control^a	IPDASi, probability dimension score/32	Rescaled IPDASi, probability dimension score (%)	CER	Logit control	ln(OR)	OR^b	RR^b
Lerman et al.[28]	A	16	33	0.66	0.65	0.37	1.46	1.12
Johnson et al. [32]	A	16	33	0.77	1.17	0.96	2.86	1.17
Wolf and Schorling [24]	B	19	46	0.54	0.16	0.73	2.08	1.31
Whelan et al. [25]	A	17	38	0.58	0.32	0.91	2.52	1.34
McBride et al. [27]	A	23	63	0.30	−0.85	0.49	1.64	1.37
Schapira and Vanruiswyk [23]	B	28	83	0.47	−0.10	0.89	2.45	1.45
Dodin et al. [31]	B	26^c	75	0.43	−0.28	0.82	2.32	1.48
O’Connor et al. [8]	C	26^c	75	0.46	−0.14	1.05	2.91	1.54
Whelan et al. [21]	B	22	58	0.37	−0.53	0.82	2.29	1.55
Kuppermann et al. [36]	C	NA	NA	0.32	−0.76	1.35	3.88	2.03
Vandemheen et al. [37]	B	30	92	0.29	−0.88	1.52	4.67	2.26
McAlister et al. [29]	A	29^d	88	0.16	−1.62	1.11	3.06	2.29
Mathieu et al. [34]	B	31	96	0.22	−1.29	1.54	4.71	2.62
Man-Son-Hing et al., [30]	A	29^d	88	0.24	−1.16	1.83	6.32	2.80
Weymiller et al. [35]	B	32	100	0.18	−1.48	1.88	6.94	3.38
Laupacis et al. [33]	A	24	67	0.08	−2.34	1.50	4.88	3.72
Gattellari and Ward [22]	B	21	54	0.10	−2.14	2.29	10.26	5.28
Chi-squared (heterogeneity)						55.75	56.41	120.19
I ²						71%	72%	87%

a A, no standardized information; B, standardized generic information (no outcome information); C, simple decision aid (no standardized probability information).
b No continuity correction was applied to match Review Manager’s output.
c Same decision aid for both trials.
d Same decision aid for both trials.
CER, control event rate; IPDASi, International Patient Decision Aid Standards instrument; NA, full decision aid not available for rating; OR, odds ratio; RR, relative risk.

ISSN: 2046-4053