Fear of pain potentiates nocebo hyperalgesia

Figures & data

Figure 1 Overview of the experimental procedure.

Table 1 Pain ratings in each trial and change scores

Group	Nocebo group			Natural History group
	(N=57, 40 females)			(N=54, 33 females)
Trial	Mean/median	SD	Min–Max	Mean/median	SD	Min–Max	U	P
Pretest	37.04/36	18.92	10 to 80	40.43/35.5	21.02	10 to 89	1,565	0.88
Posttest 1	60.20/62	19.66	20 to 96	48.37/48	21.05	7 to 98	2,183	<0.001
Posttest 2	53.16/49	20.21	14 to 98	36.97/28.5	20.73	7 to 96	2,368	<0.001
ΔPretest − Posttest 2	−16.13/−14	9.85	−36 to −8	5.73/1.5	8.33	−8 to 32	55.5	<0.001

Notes: P-values denote the difference between the groups as shown by the Mann–Whitney test. Δ = change score (Pretest − Posttest 2). N=111.

Abbreviations: SD, standard deviation; Min, minimum; Max, maximum; U, Mann–Whitney U-test.

Table 2 Stress reports in each trial and change scores

Group	Nocebo group			Natural History group
	(N=57, 40 females)			(N=54, 33 females)
Trial	Mean/median	SD	Min–Max	Mean/median	SD	Min–Max	U	P
Pretest	3.65/3	2.13	0 to 9	3.70/4	2.01	0 to 8	1,505	0.89
Posttest 1	2.56/2	1.35	1 to 9	1.82/1	1.86	0 to 7	2,128.5	<0.001
Posttest 2	2.39/2	1.25	0 to 7	1.79/2	1.57	0 to 6	1,937	0.016
ΔPretest − Posttest 2	1.08/1	2.13	−5 to 6	1.65/2	1.98	−2 to 8	1,207.5	0.045

Notes: P-values denote the difference between the groups as shown by the Mann–Whitney test. Δ = change score (Pretest − Posttest 2). N=111.

Abbreviations: SD, standard deviation; Min, minimum; Max, maximum; U, Mann–Whitney U-test.

Table 3 Big-Five Inventory-10 (BFI-10) and the Fear of Pain Questionnaire III (FPQ-III)

Measure	Mean/median	SD	Min–Max	U	P
BFI-10 personality
Extraversion	3.76/4	0.98	1.5–5	1,453	0.62
Agreeableness	3.43/3.5	1.12	1–5	1,423	0.51
Conscientiousness	3.47/3.5	0.97	1–5	1,230.5	0.08
Neuroticism	2.91/3	1.03	1–5	1,421	0.50
Openness	3.47/3.5	1.04	1.5–5	1,170	0.07
FPQ-III
FPQ severe pain	33.62/35	8.05	7–50	1,267.5	0.12
FPQ minor pain	20.19/20	6.11	10–43	1,514.5	0.91
FPQ medical pain	24.91/26	5.97	11–44	1,246.5	0.11

Notes: P-values denote the difference between the Nocebo group and the Natural History group computed from Mann–Whitney test N=111.

Abbreviations: SD, standard deviation; Min, minimum; Max, maximum; U, Mann–Whitney U-test.

Table 4 Spearman correlations between the factors of the Fear of Pain Questionnaire III (FPQ-III) and the factors of the Big-Five Inventory-10 (BFI-10) for all participants

	FPQ severe pain	FPQ minor pain	FPQ medical pain	BFI-10 extraversion	BFI-10 agreeableness	BFI-10 conscientiousness	BFI-10 neuroticism
FPQ severe pain
FPQ minor pain	0.14
FPQ medical pain	0.13	0.54**
BFI-10 extraversion	0.007	−0.13	−0.02
BFI-10 agreeableness	0.35**	−0.20*	−0.19*	0.08
BFI-10 conscientiousness	0.29**	−0.16	−0.20*	0.15	0.51**
BFI-10 neuroticism	0.12	0.34**	0.31**	−0.23*	−0.17	−0.22*
BFI-10 openness	0.19*	−0.13	−0.17	−0.08	0.32**	−0.004	−0.07

Notes:

* P<0.05;

** P<0.01; N=111. Bold values indicate significant correlations.

Figure 2 Overview of the mediation analysis for the Nocebo group.

Notes: B = regression coefficient. Pain change = Pretest − Posttest 2.