Effects of comparative information when communicating personalized risks of treatment outcomes: an experimental study

Figures & data

Figure 1. Structure of stimulus material within the 3 [comparative risk information: personalized risk-only, personalized risk above average, and personalized risk below average] × 2 [format: numerical-only, numerical + visual) between-subject design, shown for male participants receiving risks about neuropathy after chemotherapy for colon cancer. Participants either received their personalized risk without comparative data, or they received their personalized risk together with a lower generic risk or together with a higher generic risk.

Figure 2. Flowchart of the data collection process.

Table 1. Sociodemographic characteristics of respondents and non-respondents.

Characteristics	Respondents (n = 1807)		Non-respondents (n = 602)		p-value
	n	%	n	%
Gender
Female	980	54	333	55
Male	827	46	269	45	.644
Age, mean (SD)	53.9 (18.3)		40.7 (17.0)		<.001
15–24 years	142	8	104	17
25–34 years	199	11	156	26
35–44 years	213	12	124	21
45–54 years	277	15	85	14
55–64 years	356	30	68	11
>65 years	620	34	65	11	<.001
Education^a
Lower^b	472	26	130	22
Medium^c	600	33	214	36
Higher^d	729	41	256	42	.084

Note. ^a = Missing data for nine participants; ^b = Primary education, preparatory secondary vocational education; ^c = higher secondary general education or pre-university education, secondary vocational education; ^d = higher vocational education, university; SD = standard deviation.

Table A1. Sociodemographic characteristics and individual difference scores by experimental condition.

	Personalized risk-only		Personalized risk above average		Personalized risk below average		p-value
	Numerical-only (n = 299)	Numerical + visual (n = 288)	Numerical-only (n = 297)	Numerical + visual (n = 312)	Numerical-only (n = 320)	Numerical + visual (n = 291)
Gender (%)
Female	157 (53)	154 (54)	170 (57)	169 (54)	178 (56)	152 (52)
Male	142 (47)	134 (46)	127 (43)	143 (46)	142 (44)	139 (48)	.817
Age, M (SD)	52.7 (18.5)	54.2 (17.7)	54.6 (18.7)	53.4 (18.4)	55.1 (18.3)	53.5 (18.0)	.662
15–24 years	29 (10)	21 (7)	24 (8)	23 (7)	22 (7)	23 (8)
25–34 years	35 (12)	25 (9)	35 (12)	41 (13)	32 (10)	31 (11)
35–44 years	35 (12)	38 (13)	26 (9)	37 (12)	42 (13)	34 (12)
45–54 years	45 (15)	42 (15)	46 (16)	49 (15)	43 (13)	52 (18)
55–64 years	56 (18)	71 (24)	55 (18)	54 (18)	70 (22)	50 (18)
>65 years	98 (33)	91 (32)	111 (47)	108 (35)	111 (35)	101 (35)	.802
Education (%)
Lower^a	80 (27)	81 (28)	73 (25)	80 (26)	80 (25)	78 (27)
Medium^b	100 (33)	85 (30)	102 (35)	105 (34)	108 (34)	100 (35)
Higher^c	119 (40)	121 (42)	121 (40)	126 (40)	131 (41)	111 (38)	.980
Numeracy^d, M (SD)	4.01 (1.12)	4.20 (1.01)	4.13 (1.10)	4.19 (1.10)	4.09 (1.04)	4.15 (1.07)	.688
Health literacy^d, M (SD)	9.56 (2.76)	9.38 (2.82)	9.59 (2.88)	9.53 (2.63)	9.57 (2.70)	9.62 (2.97)	.935
Graph literacy^d, M (SD)	2.01 (1.06)	1.98 (1.06)	2.06 (1.01)	2.01 (1.05)	2.10 (1.05)	2.09 (1.14)	.590

Note. ^a = Primary education, preparatory secondary vocational education; ^b = higher secondary general education or pre-university education, secondary vocational education; ^c = higher vocational education, university; ^d Missing data for twenty-five patients; M = Mean; SD = standard deviation.

Figure 3. Risk estimates as a function of comparative risk strategy, shown for all three health scenarios.

Table 2. Participants’ mean scores on the primary and secondary outcomes in the colon cancer scenario across all experimental conditions.

Outcomes	Personalized risk-only			Personalized risk above average			Personalized risk below average
	Numerical-only	Numerical + visual	Total	Numerical-only	Numerical + visual	Total	Numerical-only	Numerical + visual	Total
Primary outcomes
Risk estimates	42.4 (17.9)	40.7 (16.4)	41.5 (17.2)	38.0 (15.5)	39.9 (17.1)	39.0 (16.3)^a***	42.8 (16.6)	43.0 (17.0)	42.9 (16.8)
Risk perception	3.04 (0.81)	3.04 (0.82)	3.04 (0.81)	3.04 (0.85)	3.11 (0.81)	3.08 (0.83)	3.09 (0.76)	3.03 (0.82)	3.06 (0.79)
Affective evaluation	3.23 (0.96)	3.16 (0.94)	3.20 (0.95)	3.22 (0.97)	3.22 (0.96)	3.22 (0.96)	3.21 (0.94)	3.28 (0.92)	3.24 (0.93)
Secondary outcomes
Perceived personal relevance	2.97 (0.95)	2.92 (0.86)	2.95 (0.90)	2.97 (0.96)	3.09 (0.97)	3.04 (0.96)	3.07 (0.92)	3.00 (0.90)	3.04 (0.91)
Treatment intention	3.63 (1.13)	3.55 (1.03)^b*	3.59 (1.08)	3.53 (1.07)	3.47 (1.09)^b*	3.50 (1.08)	3.62 (1.10)	3.47 (1.03)^b*	3.55 (1.07)

Note. Standard deviations within parentheses; Control variables include age, gender, education, subjective numeracy, health literacy, and graph literacy; ^a Mean differs significantly compared to total personalized risk-only and personalized below average conditions; ^b Total numerical + visual format differs significantly compared to total numerical-only format; *p < .05, **p < .01, ***p < .001.

Table B1. Main and interaction effects on primary outcome measures resulting from a 3 × 2 MANCOVA and on the secondary outcome variables resulting from two separate 3 × 2 ANCOVAs for the colon cancer scenario.

Main/interaction effects	Primary outcome variables									Secondary outcome variables
	Risk estimates			Risk perception			Affective evaluation			Perceived personal relevance			Treatment intention
	F	p	ηp^2	F	p	ηp^2	F	p	ηp^2	F	p	ηp^2	F	p	ηp^2
Comparative risk information^a	8.27	<.001	.009	0.16	.854	.000	0.22	.801	.000	1.71	.182	.002	1.60	.202	.002
Message format^b	0.00	.952	.000	0.01	.925	.000	0.02	.896	.000	0.04	.834	.000	4.04	.045	.002
Comparative risk information × Message format^a	1.88	1.53	.002	0.94	.389	.001	0.90	.406	.001	2.12	.120	.002	0.32	.728	.000

Note. ^adf = 2, 1741; ^bdf = 1, 1741; Covariates include age, gender, education, subjective numeracy, health literacy, and graph literacy; Significant results are given in bold.

Table 3. Participants’ mean scores on the primary and secondary outcomes in the increased cholesterol scenario across all experimental conditions.

Outcomes	Personalized risk-only			Personalized risk above average			Personalized risk below average
	Numerical-only	Numerical + visual	Total	Numerical-only	Numerical + visual	Total	Numerical-only	Numerical + visual	Total
Primary outcomes
Risk estimates	31.4 (18.8)	29.6 (18.1)	30.5 (18.4)	27.7 (16.8)	29.2 (17.9)	28.4 (17.4)^a*	31.3 (18.6)	31.0 (18.8)	31.2 (18.7)
Risk perception	2.60 (0.88)	2.44 (0.85)^b*	2.52 (087)	2.51 (0.80)	2.50 (0.85)^b*	2.50 (0.83)	2.57 (0.88)	2.46 (0.90)^b*	2.52 (0.89)
Affective evaluation	2.41 (0.98)	2.33 (0.90)^b*	2.47 (1.01)	2.40 (0.98)	2.35 (0.96)^b*	2.37 (0.94)	2.50 (1.03)	2.43 (0.97)^b*	2.38 (0.97)
Secondary outcomes
Perceived personal relevance	2.80 (0.98)	2.72 (0.95)	2.76 (0.97)	2.79 (0.94)	2.93 (1.02)	2.86 (0.98)	2.95 (0.96)	2.87 (1.00)	2.91 (0.98)^c*
Treatment intention	3.38 (1.15)	3.46 (1.18)	3.42 (1.16)	3.34 (1.15)	3.27 (1.16)	3.31 (1.16)	3.32 (1.21)	3.34 (1.21)	3.33 (1.21)

Note. Standard deviations within parentheses; Control variables include age, gender, education, subjective numeracy, health literacy, and graph literacy; ^a Mean differs significantly compared to total personalized risk-only and personalized below average conditions; ^b Total numerical + visual format differs significantly compared to total numerical-only format; ^c Mean differs significantly compared to total personalized risk-only condition; *p < .05, **p < .01, ***p < .001.

Table B2. Main and interaction effects on primary outcome measures resulting from a 3 × 2 MANCOVA and on the secondary outcome variables resulting from two separate 3 × 2 ANCOVAs for the increased cholesterol scenario.

Main/interaction effects	Primary outcome variables									Secondary outcome variables
	Risk estimates			Risk perception			Affective evaluation			Perceived personal relevance			Treatment intention
	F	p	ηp^2	F	p	ηp^2	F	p	ηp^2	F	p	ηp^2	F	p	ηp^2
Comparative risk information^a	3.65	.026	.004	0.04	.960	.000	1.32	.267	.004	3.73	.024	.004	1.41	.244	.002
Message format^b	0.11	.741	.000	5.47	.019	.003	4.20	.041	.002	0.17	.681	.000	0.03	.854	.000
Comparative risk information × Message format^a	1.36	.258	.002	1.16	.314	.001	0.91	.404	.001	2.50	.083	.003	0.62	.540	.001

Note. ^adf = 2, 1741; ^bdf = 1, 1741; Covariates include age, gender, education, subjective numeracy, health literacy, and graph literacy; Significant results are given in bold.

Table 4. Participants’ mean scores on the primary and secondary outcomes in the skin cancer scenario across all experimental conditions.

Outcomes	Personalized risk-only			Personalized risk above average			Personalized risk below average
	Numerical-only	Numerical + visual	Total	Numerical-only	Numerical + visual	Total	Numerical-only	Numerical + visual	Total
Primary outcomes
Risk estimates	24.4 (18.7)	22.3 (16.9)	23.4 (17.9)	22.0 (16.8)	24.0 (19.5)	23.0 (18.2)	24.1 (16.8)	25.0 (19.1)	24.5 (17.9)
Risk perception	2.16 (0.85)	2.06 (0.77)	2.11 (0.81)	2.18 (0.79)	2.09 (0.89)	2.13 (0.84)	2.14 (0.77)	2.13 (0.90)	2.14 (0.83)
Affective evaluation	2.45 (0.98)	2.25 (0.89)^c**	2.36 (0.94)	2.37 (0.99)	2.23 (0.99)^c**	2.30 (0.99)	2.44 (1.00)	2.35 (1.04)^c**	2.40 (1.02)
Secondary outcomes
Perceived personal relevance	2.71 (1.00)	2.59 (0.96)	2.65 (0.98)	2.68 (0.96)	2.79 (1.07)	2.73 (1.02)	2.80 (1.02)	2.78 (1.02)	2.79 (1.02)^a*
Treatment intention	3.74 (1.17)	3.82 (1.14)	3.78 (1.16)	3.69 (1.18)	3.72 (1.18)	3.70 (1.18)	3.69 (1.20)	3.76 (1.14)	3.72 (1.17)

Note. Standard deviations within parentheses; Control variables include age, gender, education, subjective numeracy, health literacy, and graph literacy; ^a Mean differs significantly compared to total personalized risk-only condition; ^b Total numerical + visual format differs significantly compared to total numerical-only format; *p <. 05, **p < .01, ***p < .001.

Table B3. Main and interaction effects on primary outcome measures resulting from a 3 × 2 MANCOVA and on the secondary outcome variables resulting from two separate 3 × 2 ANCOVAs for the skin cancer scenario.

Main/interaction effects	Primary outcome variables									Secondary outcome variables
	Risk estimates			Risk perception			Affective evaluation			Perceived personal relevance			Treatment intention
	F	p	ηp^2	F	p	ηp^2	F	p	ηp^2	F	p	ηp^2	F	p	ηp^2
Comparative risk information^a	1.28	.279	.001	0.22	.803	.000	1.30	.272	.001	3.26	.039	.004	1.05	.351	.001
Message format^b	0.03	.853	.000	3.50	.062	.002	10.15	.001	.006	0.20	.653	.000	1.03	.310	.001
Comparative risk information × Message format^a	2.32	.099	.003	0.35	.702	.000	0.47	.628	.001	1.60	.202	.002	0.04	.965	.000

Note. ^adf = 2, 1741; ^bdf = 1, 1741; Covariates include age, gender, education, subjective numeracy, health literacy, and graph literacy; Significant results are given in bold.

Data availability statement

The data can be accessed via https://tiu.nu/osf/q2dcz.