Table 4.
Baseline characteristics of the study participants grouped by cluster membership.
| Persistent NCP | Migration from NCP to CRP/CWP | Persistent CRP or migration between CRP and NCP | Migration from CRP to CWP | Persistent CWP | P* | |
|---|---|---|---|---|---|---|
| N | 1052 | 92 | 411 | 184 | 119 | |
| Age group n (%) | ||||||
| 20-29 | 233 (22) | 10 (11) | 41 (10) | 18 (10) | 6 (5) | <0.001 |
| 30-39 | 201 (19) | 20 (22) | 60 (15) | 35 (19) | 11 (9) | |
| 40-49 | 229 (22) | 31 (34) | 90 (22) | 43 (23) | 24 (20) | |
| 50-59 | 215 (20) | 17 (19) | 101 (25) | 44 (24) | 33 (28) | |
| 60-74 | 174 (17) | 14 (15) | 119 (29) | 44 (24) | 45 (38) | |
| Gender n (%) | ||||||
| Female | 543 (52) | 50 (54) | 227 (55) | 119 (65) | 88 (74) | <0.001 |
| Male | 509 (48) | 42 (46) | 184 (45) | 65 (35) | 31 (26) | |
| Problem with sleep: n (%) | ||||||
| Initiating sleep | 138 (14) | 15 (17) | 121 (30) | 60 (33) | 56 (48) | <0.001 |
| Maintaining sleep | 173 (17) | 22 (24) | 186 (47) | 87 (48) | 84 (72) | <0.001 |
| Non-restorative sleep | 183 (18) | 26 (29) | 159 (41) | 98 (55) | 87 (74) | <0.001 |
| Early awakening | 118 (12) | 19 (21) | 128 (33) | 62 (35) | 62 (54) | <0.001 |
| No of sleep problems n (%) | ||||||
| 0 | 678 (67) | 49 (54) | 139 (36) | 53 (30) | 15 (13) | <0.001 |
| 1 | 168 (17) | 18 (20) | 74 (19) | 37 (21) | 11 (10) | |
| ≥2 | 158 (16) | 23 (26) | 172 (45) | 86 (49) | 86 (77) | |
| Socioeconomic status by work n (%) | ||||||
| Nonmanual | 474 (45) | 42 (46) | 155 (38) | 59 (32) | 31 (26) | <0.001 |
| Manual | 431 (41) | 42 (46) | 208 (51) | 110 (60) | 75 (63) | |
| Others† | 147 (14) | 8 (9) | 48 (12) | 15 (8) | 13 (11) | |
| Alcohol n (%) | ||||||
| Never or seldom | 301 (29) | 26 (28) | 152 (37) | 79 (43) | 66 (55) | <0.001 |
| Once a month | 469 (45) | 40 (44) | 162 (40) | 69 (38) | 32 (27) | |
| 1-2 times per week or daily | 278 (26) | 26 (28) | 96 (23) | 35 (19) | 18 (15) | |
| Smoking n (%) | ||||||
| Never/previous smoker | 849 (81) | 74 (80) | 323 (79) | 136 (74) | 90 (76) | 0.197 |
| Smoker | 198 (19) | 18 (20) | 86 (21) | 48 (26) | 28 (24) | |
| Immigrant n (%) | <0.001 | |||||
| Yes | 85 (8) | 13 (14) | 41 (10) | 27 (15) | 27 (23) | |
| No | 961 (92) | 79 (86) | 366 (90) | 157 (85) | 90 (77) | |
| Regular exercise n (%) | ||||||
| No | 425 (41) | 36 (40) | 182 (45) | 85 (46) | 41 (35) | 0.631 |
| Yes, 1-2 times/week | 373 (36) | 32 (36) | 133 (33) | 59 (32) | 48 (41) | |
| Yes, >2 times/week | 243 (23) | 22 (24) | 94 (23) | 39 (21) | 27 (23) | |
| SF36 mean (sd) | ||||||
| Physical function | 93.9 (11.2) | 91.0 (13.9) | 81.8 (18.9) | 77.5 (20.0) | 58.0 (24.1) | <0.001 |
| Role function, physical | 91.8 (23.0) | 85.7 (31.7) | 70.2 (39.1) | 58.4 (40.5) | 37.9 (41.6) | <0.001 |
| Bodily pain | 84.9 (19.8) | 81.1 (23.1) | 57.3 (21.6) | 51.1 (21.2) | 36.1 (17.7) | <0.001 |
| General health | 83.9 (16.3) | 78.5 (18.6) | 67.1 (22.1) | 58.9 (22.5) | 44.5 (20.8) | <0.001 |
| Vitality | 76.4 (19.0) | 69.6 (21.9) | 62.6 (22.1) | 52.9 (24.1) | 39.9 (21.3) | <0.001 |
| Social function | 93.9 (14.1) | 89.5 (19.5) | 86.8 (21.1) | 78.9 (24.9) | 67.5 (26.8) | <0.001 |
| Role function, emotional | 91.7 (23.0) | 83.9 (31.0) | 79.2 (35.1) | 69.5 (40.4) | 60.2 (40.7) | <0.001 |
| Mental health | 86.0 (15.2) | 80.6 (18.3) | 78.2 (19.4) | 70.1 (21.9) | 64.8 (21.7) | <0.001 |
| No. of pain regions (0-18) | ||||||
| Mean (SD) | 0.3 (1.2) | 0.0 (0.0) | 3.1 (2.8) | 4.1 (3.0) | 10.0 (3.7) | <0.001 |
| Median (IQR) | 0 (0) | 0 (0) | 3 (4) | 4 (4) | 9 (5) | |
| Care seek pain n (%) | ||||||
| Yes | 305 (32) | 31 (37) | 188 (59) | 98 (69) | 65 (82) | <0.001 |
| No | 650 (68) | 53 (63) | 131 (41) | 45 (32) | 14 (18) | <0.001 |
| Social support n (%) | ||||||
| Yes/yes probably | 952 (91) | 79 (88) | 348 (85) | 140 (77) | 92 (78) | <0.001 |
| No/not sure | 97 (9) | 11 (12) | 62 (15) | 42 (23) | 26 (22) |
*
Differences in covariates between clusters were analysed by ANOVA for means, Kruskal–Wallis for medians, and chi-square tests for proportions.
†
Others include self-employed, housewives, and students.
ANOVA, analysis of variance; CRP, chronic regional pain; CWP, chronic widespread pain; NCP, no chronic pain.