Clinical and psychological moderators of the effect of mindfulness-based cognitive therapy on persistent pain in women treated for primary breast cancer – explorative analyses from a randomized controlled trial

Figures & data

Figure 1. CONSORT study flow diagram.

Table 1. Sociodemographic and clinical characteristics of study sample at baseline^a.

Demographicsb	MBCT group (n = 67)	Control group (n = 62)	pc
Age (years), Mean (SD) [N]	56.8 (9.99)	56.7 (8.10)	0.96
Marital status, N (%)			0.50
Married/cohabiting	47 (70.1)	40 (64.5)
Not cohabiting/single	20 (29.9)	22 (35.5)
Educational level, N (%)c			0.18
Lower (<2 years of further education)	21 (31.3)	28 (45.2)
Medium (2–4 years of further education)	36 (53.7)	29 (46.8)
Long (≥5 years of further education)	9 (13.4)	4 (6.5)
Missing	1 (1.5)	1 (1.6)
Occupational status, N (%)			0.53
Full- or part-time employed	29 (43.3)	22 (35.5)
Unemployed or on sickness benefit	10 (14.9)	8 (12.9)
Retired	24 (35.8)	28 (45.2)
Missing	4 (6.0)	4 (6.5)
CLINICAL CHARACTERISTICS
Time since surgery (months), Mean (SD) [N]	40.0 (24.56) [66]	43.2 (34.82) [62]	0.54
Tumor size, N (%)			0.42
≤20 mm	36 (53.7)	30 (48.4)
>20 mm ≤50 mm	27 (40.3)	31 (50.0)
>50 mm	1 (1.5)	0 (0.0)
Not reported	3 (4.5)	1 (1.6)
Type of surgery, N (%)			0.26
Mastectomy	27 (40.3)	32 (51.6)
Lumpectomy	38 (56.7)	30 (48.4)
Not reported	2 (3.0)	–
Axillary lymph node dissection (ALND), N (%)			0.32
Yes	39 (58.2)	32 (51.6)
No	26 (38.8)	28 (45.2)
Not reported	2 (3.0)	2 (3.2)
ER status, N (%)e			0.29
Positive (≥1%)	55 (82.1)	55 (88.7)
Negative (<1%)	5 (17.9)	7 (11.3)
HER2 status, N (%)			0.48
Positive	6 (9.0)	8 (12.9)
Negative	54 (9.0)	46 (74.2)
Not reported	8 (11.9)	6 (9.7)
Chemotherapy, N (%)			0.47
Yes	38 (56.7)	39 (62.9)
No	29 (43.3)	23 (37.1)
Radiotherapy, N (%)			0.20
Yes	54 (80.6)	48 (77.4)
No	7 (10.4)	12 (19.4)
Not reported	6 (9.0)	2 (3.2)
Endocrine treatment, N (%)			0.26
Yes	46 (68.7)	48 (77.4)
No	21 (31.3)	14 (22.6)
Active endocrine treatment during study period, N (%)			0.42
Yes	41 (61.2)	40 (64.5)
No	5 (7.5)	8 (12.9)
PRIMARY OUTCOME MEASURE
Pain intensity (11-point NRS), Mean (SD) [N]	5.5 (2.09) [60]	5.3 (2.56) [56]	0.57
PSYCHOLOGICAL MEASURES
HADS total score^f, Mean (SD) [N]	16.5 (6.66) [67]	18.1 (7.47) [61]	0.22
ECR-SF^g, Mean (SD) [N]
Anxiety	22.2 (6.87) [67]	23.8 (7.53) [61]	0.21
Avoidance	17.9 (7.67) [66]	19.0 (8.16) [61]	0.41
TAS-20^h, Mean (SD) [N]	44.8 (12.2) [67]	46.6 (11.6) [61]	0.39

^a The total sample consists of 129 women; ^bWhen reporting categorical variables, number of patients and percent are shown. When reporting continuous variables, mean (M), standard deviation (SD), and number of patients [N] are shown; ^cStatistically significant group differences (p < 0.05) are shown in boldface; ^dFurther education refers to years of education further than high school; ^eThe number of women with ER-positive tumors and the number of women receiving endocrine treatment differs slightly. This can be explained by (1) the indication for endocrine treatment was changed in 2010 (from ≥10% to ≥1% ER-positive tumor cells), thus women with 1–9% ER-positive tumor cells treated prior to 2010 were not offered endocrine treatment; (2) a number of patients will have declined receiving endocrine treatment or may have ended their endocrine treatment prematurely due to side effects; ^fThe Hospital and Depression Scale [20]; ^gThe Experiences in Close Relationships Scale Short Form [22]; ^hThe 20-item Toronto Alexithymia Scale [23].

Figure 2. Interaction effects of radiotherapy on pain intensity [11-point numeric rating scale, (NRS)].

Table 2. Results from moderation analyses in mixed linear models.

	F	p^a	95% Confidence intervals (CI)	d
Clinical moderators
Age	0.3	0.582	−0.13–0.23	0.08
Active endocrine treatment during study period	1.1	0.300	−0.36–1.66	0.16
Radiotherapy	3.3	0.075	−0.56–11.45	0.49
Radiotherapy +/− axillary lymph node dissection	2.5	0.113	−0.72–6.64	0.28
Psychological moderators
Psychological distress (HADS^b)	0.8	0.375	−0.33–0.12	0.14
Adult attachment: anxiety (ECR-SF^c)	1.1	0.303	−0.32–0.10	0.17
Adult attachment: avoidance (ECRS-SF^c)	5.1	0.026	−0.42–−0.03	0.36
Alexithymia (TAS-20^d)	0.1	0.707	−0.16–0.11	0.06

^a Statistically significant results are shown in bold face; ^bThe Hospital Anxiety and Depression Scale [20]; ^cThe Experiences in Close Relationships Scale Short Form [22]; ^dThe 20-item Toronto Alexithymia Scale [23].

Figure 3. Interaction effects of attachment avoidance on pain intensity [11-point numeric rating scale, (NRS)].

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