Table 6. Pain, comorbidity, and psychosocial factors of 4 sensory-clinical phenotypes of patients with previous FMS and CBP diagnoses.
Variable† |
Cluster |
Difference‡ between clusters 1 and 2 and clusters 3 and 4 |
1 (N = 47) |
2 (N = 21) |
3 (N = 58) |
4 (N = 33) |
Age (y) |
49.9 ± 8.9 [22–63] |
48.4 ± 12.9 [23–69] |
50.2 ± 11.3 [23–68] |
47.5 ± 13.7 [18–67] |
n. s. |
Sex (f/m) |
45/2 |
19/2 |
39/19 |
20/13 |
χ2(1,4); P < 0.001*** |
Chronicity§ |
|
|
|
|
|
Duration (mo) |
50 ± 27 [60 ± 18] |
50 ± 28 [60 ± 9] |
48 ± 27 [60 ± 18] |
48 ± 34 [60 ± 18] |
n. s. |
CPG |
3.1 ± 1.2 [3.5 ± 1.0] |
2.8 ± 1.1 [3.0 ± 1.0] |
2.2 ± 1.2 [2.0 ± 1.0] |
2.2 ± 1.4 [1.0 ± 1.5] |
P < 0.001***d = 0.650 |
Pain characteristics|| |
|
|
|
|
|
WPI |
12.1 ± 3.7 [13.0 ± 3.0] |
11.2 ± 4.1 [11.0 ± 3.0] |
6.2 ± 3.0 [5.0 ± 1.6] |
5.0 ± 3.2 [4.0 ± 2.0] |
P < 0.001***d = 1.773 |
Intensity |
3.3 ± 1.24 [3.0 ± 0.5] |
3.4 ± 1.3 [4.0 ± 0.5] |
2.9 ± 1.17 [3.0 ± 1.0] |
3.1 ± 1.46 [3.0 ± 1.0] |
P = 0.012*d = 0.395 |
Severity |
3.8 ± 1.1 [3.7 ± 0.9] |
3.9 ± 1.1 [4.0 ± 1.2] |
3.2 ± 1.1 [3.0 ± 0.9] |
3.6 ± 1.1 [3.5 ± 0.7] |
P = 0.005*d = 0.462 |
Pain impact¶ |
|
|
|
|
|
FM impact |
56.6 ± 18.6 [55.8 ± 13.4] |
53.7 ± 14.3 [56.3 ± 12.7] |
42.9 ± 14.8 [42.4 ± 12.9] |
39.9 ± 19.8 [34.4 ± 14.9] |
P < 0.001***d = 0.797 |
Interference |
3.5 ± 1.4 [3.8 ± 1.2] |
3.3 ± 1.4 [3.6 ± 0.9] |
2.4 ± 1.2 [2.5 ± 0.9] |
3.4 ± 1.4 [3.6 ± 1.2] |
P = 0.008*d = 0.504 |
Functional capacity |
54.5 ± 16.9 [54.2 ± 13.4] |
57.5 ± 15.2 [58.3 ± 11.5] |
74.6 ± 17.3 [75.0 ± 10.4] |
68.3 ± 20.0 [70.8 ± 13.5] |
P < 0.001***d = 0.967 |
Pain cognitions# |
|
|
|
|
|
Catastrophizing |
2.6 ± 1.1 [2.6 ± 0.9] |
2.3 ± 0.6 [2.3 ± 0.3] |
1.8 ± 0.9 [1.9 ± 0.8] |
1.7 ± 1.1 [1.6 ± 0.6] |
P < 0.001**d = 0.826 |
Return to work |
12.9 ± 9.8 [12.0 ± 9.5] |
9.6 ± 8.8 [7.0 +7.5] |
6.9 + 9.1 [5.0 ± 4.5] |
9.9 ± 8.0 [11.5 ± 8.4] |
P = 0.061 |
Somatic symptoms†† |
|
|
|
|
|
GBB sum |
46.9 ± 16.8 [50.0 ± 12.0] |
38.0 ± 10.3 [38.0 ± 6.0] |
30.1 ± 14 [26.0 ± 10.5] |
24.6 ± 15.5 [19.0 ± 9.8] |
P < 0.001***d = 1.273 |
GBB exhaustion |
14.6 ± 5.8 [15.0 ± 4.8] |
12.2 ± 4.6 [12.0 ± 4.8] |
9.5 ± 5.8 [9.0 ± 4.0] |
7.8 ± 6.6 [6.0 ± 4.3] |
P < 0.001***d = 0.849 |
GBB gastrointest. |
7.6 ± 5.6 [7.0 ± 4.1] |
5.0 ± 3.0 [5.0 ± 2.5] |
4.1 ± 3.4 [3.0 ± 2.5] |
3.3 ± 4.0 [2.0 ± 3.0] |
P < 0.001***d = 0.674 |
GBB cardiovascul. |
7.0 ± 4.3 [6.5 ± 3.1] |
5.4 ± 3.5 [5.0 ± 3.0] |
3.9 ± 3.6 [3.0 ± 2.5] |
2.7 ± 3.6 [2.0 ± 2.0] |
P < 0.001***d = 0.794 |
GBB musc.-skeletal |
17.3 ± 4.5 [17.0 ± 3.1] |
15.2 ± 4.1 [16.0 ± 2.3] |
12.6 ± 4.4 [12.0 ± 3.0] |
10.8 ± 4.2 [11.0 ± 3.8] |
P < 0.001***d = 1.072 |
SF-12 physical |
29.6 ± 7.2 [29.1 ± 5.2] |
35.2 ± 9.9 [32.4 ± 5.7] |
38.4 ± 9.0 [38.8 ± 7.0] |
35.6 ± 9.2 [38.1 ± 8.1] |
P < 0.001***d = 0.690 |
PSQI sleep |
10.3 ± 4.3 [11.0 ± 2.8] |
11.7 ± 3.8 [12.0 ± 2.4] |
9.0 ± 4.4 [8.0 ± 3.2] |
7.9 ± 4.8 [8.0 ± 3.5] |
P = 0.028 |
FGID [N (%)] |
18 (38.3) |
9 (42.9) |
12 (20.7) |
1 (3.0) |
P = 0.006*d = 0.390 |
Comorbidity with mental disorder‡‡ |
|
|
|
|
|
Anxiety |
48.3 ± 12.5 [47.0 ± 10.5] |
50.7 ± 10.8 [51.5 ± 9.4] |
43.7 ± 9.5 [41.0 ± 7.5] |
42.2 ± 11.2 [39.0 ± 6.8] |
P = 0.012 |
Depression |
22.3 ± 12.3 [21.0 ± 9.0] |
20.3 ± 12.3 [20.0 ± 5.0] |
19.6 ± 9.8 [17.5 ± 6.1] |
19.6 ± 13.0 [16.0 ± 7.5] |
P = 0.262 |
Psychosoc. factors§§ |
|
|
|
|
|
Stress perception |
34.2 ± 15.8 [34.0 ± 12.8] |
36.7 ± 13.5 [35.0 ± 12.0] |
30.8 ± 12.9 [28.5 ± 11.4] |
25.7 ± 10.7 [25.5 ± 8.6] |
P = 0.067 |
Social support |
3.6 ± 1.7 [3.8 ± 1.3] |
3.3 ± 1.8 [4.0 ± 1.5] |
2.8 ± 1.7 [3.0 ± 1.4] |
3.2 ± 1.7 [3.5 ± 1.1] |
P = 0.076 |
Solicitous response |
3.2 ± 1.6 [3.2 ± 1.5] |
3.0 ± 1.6 [3.4 ± 1.4] |
2.5 ± 1.4 [2.6 ± 1.2] |
2.7 ± 1.5 [2.8 ± 1.2] |
P = 0.030 |
†Mean ± SD, medians ± 0.5 interquartile distances in brackets; frequencies and range for categorical variables.
‡Exact probabilities of the ex-post t test (or U test if required); effect sizes according to scale levels: Cohen's d (interval), z values transformed to η2 (ordinal) or phi coefficient (nominal) of the cluster-pair difference between clusters 1 and 2 and clusters 3 and 4 after a significant H-test or contingency test. Significance levels Bonferroni–Holm corrected, familywise for the independent domains pain characteristics and chronicity (k = 7), pain impact (k = 4), pain cognitions and coping (k = 7), comorbidity (k = 12), psychosocial factors, and stress (k = 13). *P < 0.05; **P < 0.01; ***P < 0.001 after correction; variables with differences P > 0.10 not shown but included in correction.
§CPG,43 Md ± 0.5 IQD, and frequencies of individual grades, expected frequencies in parentheses.
||WPI: range 0–19 according to the FSQ,28 the survey version of the FS scale.71 Intensity: item #1 of the MPI-D;17 Severity: MPI-D = scale value.
¶FM Impact: Fibromyalgia Impact Questionnaire (German version51; original version8); Interference: MPI-D scale; Functionality: FFbH-R.42
#Catastrophizing: PRSS;16 Belief return to work: FABQ.53
††GBB sum: total somatic load, sum score of the Giessen Subjective Complaints List (GBB-24);6 GBB subscales: exhaustion; gastrointestinal, musculoskeletal complaints; SF-12 physical: somatic component of the Health-Related Quality of Life Questionnaire—Short Version (SF-12)7; PSQI sleep: sum score of the Pittsburgh Sleeping Quality Index;9 FGID [N (%)]: absolute/relative frequency of functional g. i. t. disorders according to the self-report questionnaire for functional gastrointestinal disorders (functional dyspepsia/nonulcer dyspepsia and/or irritable bowel syndrome).31
‡‡STAI-T44 Center for Epidemiological Studies Depression Scale—German Version (ADS).30
§§Stress load: subjective global strain load according to the BSS (German "Kurzer Fragebogen zur Erfassung von Belastungen")15; Social support: MPI-D17; Solicitous resp.: MPI-D scale solicitous response of spouse.
BSS, Brief Stress Scale; CBP, chronic primary back pain; CPG, Chronic Pain Grade; FAPQ, Fear-Avoidance-Beliefs Questionnaire; FFbH, Hannover Functional Ability Questionnaire; FGID, functional gastrointestinal disorders; FMS, fibromyalgia syndrome; FS scale, Fibromyalgia Symptom scale; FSQ, Fibromyalgia Survey Questionnaire; IQD, interquartile distance; MPI, Multidimensional Pain Inventory; PRSS, Pain-Related Self-Statements Scale; PSQI, Pittsburgh Sleep Quality Index; STAI-T, Trait Anxiety Scale of the State-Trait Anxiety Inventory; WPI, Widespread Pain Index.