Table 2.
Characteristics of patients in the six pain trajectories
| Pain trajectory groups | ||||||
|---|---|---|---|---|---|---|
|
| ||||||
| Characteristic | A (constant mild pain) | C (moderate regression) | E (major regression) | B (severe progression) | D (moderate progression) | F (constant severe) |
|
| ||||||
| n = 186 | n = 207 | n = 23 | n = 35 | n = 180 | n = 74 | |
|
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| Age, years (SD) | 56 (0.4) | 56 (0.4) | 57 (1.1) | 55 (0.9) | 56 (0.4) | 56 (0.5) |
|
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| Female, % | 80 | 79 | 83 | 80 | 83 | 85 |
|
| ||||||
| BMI (SD)a,b | 25 (0.3) | 26 (0.3) | 25 (0.8) | 26 (0.8) | 27 (0.3) | 28 (0.6) |
|
| ||||||
| Highest achieved education levela,b | ||||||
| Primary or secondary school, % | 62 | 77 | 68 | 83 | 83 | 83 |
| University/college, % | 38 | 23 | 32 | 17 | 17 | 17 |
|
| ||||||
| White ethnicity, % | 99 | 98 | 100 | 97 | 97 | 92 |
|
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| Participants with >1 comorbidity, %a,b | 32 | 48 | 59 | 57 | 49 | 69 |
|
| ||||||
| NRS in past week (IQR)a,b | 2.1 (1.0–3.0) | 3.4 (2.0–4.0) | 5.6 (5.0–7.0) | 2.3 (1.0–3.0) | 4.5 (4.0–6.0) | 6.2 (5.0–7.0) |
|
| ||||||
| NRS at moment of questionnaire (IQR)a,b | 1.7 (1.0–2.0) | 2.9 (2.0–4.0) | 4.5 (3.0–6.0) | 2.1 (1.0–3.0) | 4.0 (3.0–5.0) | 5.9 (5.0–7.0) |
|
| ||||||
| PCI subscales score | ||||||
| Pain transformation (IQR)a,b | 2.0 (1.5–2.5) | 2.1 (1.8–2.5) | 2.4 (1.9–3.0) | 2.2 (1.5–2.8) | 2.3 (1.8–2.8) | 2.4 (2.0–2.8) |
| Distraction (IQR)a,b | 2.1 (1.6–2.6) | 2.2 (1.8–2.6) | 2.2 (1.8–2.7) | 2.3 (1.6–3.0) | 2.3 (1.8–2.6) | 2.5 (2.2–2.8) |
| Reducing demands (IQR)a,b | 1.9 (1.7–2.3) | 2.0 (1.7–2.7) | 2.3 (2.0–2.8) | 1.9 (1.7–2.0) | 2.0 (1.7–2.7) | 2.3 (2.0–2.7) |
| Retreating (IQR)a,b | 1.5 (1.1–1.9) | 1.6 (1.1–1.9) | 1.7 (1.1–2.0) | 1.5 (1.1–1.9) | 1.5 (1.1–1.7) | 1.7 (1.3–2.0) |
| Worrying (IQR)a,b | 1.4 (1.2–1.7) | 1.5 (1.2–1.8) | 1.7 (1.4–1.9) | 1.6 (1.3–1.9) | 1.6 (1.3–1.9) | 1.8 (1.4–2.1) |
| Resting (IQR)a,b | 1.7 (1.4–2.0) | 1.8 (1.4–2.0) | 2.0 (1.6–2.3) | 1.7 (1.4–1.8) | 1.9 (1.6–2.2) | 2.1 (1.6–2.6) |
|
| ||||||
| WOMAC subscales score | ||||||
| Pain (IQR)a,b | 15 (5–20) | 24 (10–33) | 39 (25–55) | 19 (10–30) | 33 (25–40) | 46 (25–60) |
| Joint stiffness (IQR)a,b | 24 (13–38) | 34 (25–50) | 48 (38–63) | 24 (13–38) | 42 (25–50) | 53 (38–63) |
| Physical function (IQR)a,b | 14 (6–21) | 23 (11–31) | 37 (26–49) | 16 (6–21) | 31 (19–41) | 45 (33–58) |
|
| ||||||
| Uses pain medication, % | 36 | 38 | 26 | 35 | 39 | 44 |
|
| ||||||
| Drinks alcohol, %a | 78 | 78 | 91 | 74 | 76 | 63 |
|
| ||||||
| Smoker or previous smoker, % | 11 | 12 | 18 | 14 | 16 | 18 |
|
| ||||||
| Has additional supplements or vitamin intake, % | 54 | 52 | 46 | 51 | 52 | 57 |
|
| ||||||
| Pain in the ipsilateral hip, %a,b | 28 | 42 | 74 | 31 | 49 | 51 |
|
| ||||||
| Morning stiffness knees <30 minutes, %a,b | 64 | 67 | 61 | 59 | 76 | 80 |
|
| ||||||
| Palpable warmth knee, % | 6 | 6 | 9 | 0 | 6 | 4 |
|
| ||||||
| Joint space tenderness knee, %a,b | 36 | 51 | 52 | 61 | 70 | 68 |
|
| ||||||
| Bony enlargement knee, % | 4 | 4 | 0 | 9 | 6 | 4 |
|
| ||||||
| Crepitus during flexion knee, % | 53 | 56 | 43 | 51 | 50 | 57 |
|
| ||||||
| Positive re-fill test knee, % | 10 | 9 | 9 | 3 | 9 | 6 |
|
| ||||||
| ROM flexion knee, degrees (SD)a | 135 (1) | 134 (1) | 134 (2) | 132 (2) | 134 (1) | 131 (2) |
|
| ||||||
| ROM extension knee, degrees (SD) | 3 (0) | 3 (0) | 3 (0) | 3 (0) | 3 (0) | 3 (0) |
|
| ||||||
| Pain during active flexion knee, %a,b | 32 | 33 | 13 | 32 | 39 | 46 |
|
| ||||||
| Pain during active extension knee, %a | 12 | 21 | 18 | 12 | 24 | 29 |
|
| ||||||
| Pain during active internal rotation ipsilateral hip, %a,b | 20 | 28 | 55 | 25 | 39 | 46 |
|
| ||||||
| Bouchard swelling digit. 2–5 left or right, % | 18 | 19 | 17 | 20 | 19 | 24 |
|
| ||||||
| Heberden node digit. 2–5 left or right, % | 48 | 50 | 44 | 31 | 47 | 58 |
|
| ||||||
| Erythrocyte sedimentation rate, mm/hr (SD)a | 9.7 (0.6) | 9.4 (0.5) | 12.5 (2.3) | 9.9 (1.3) | 10.9 (0.6) | 12.3 (1.1) |
|
| ||||||
| Kellgren–Lawrence grade | ||||||
| Distribution, % knees with grade 0/1 | 57/43 | 63/37 | 70/30 | 56/44 | 55/45 | 49/51 |
|
| ||||||
| Kellgren–Lawrence score ipsilateral hip | ||||||
| Distribution, % hips with grade 0/1 | 81/19 | 75/25 | 70/30 | 85/15 | 80/20 | 79/21 |
|
| ||||||
| TKA after 5 years follow-up, total | 1 | 2 | 0 | 0 | 8 | 3 |
a
P-value <0.10 from the univariate multinomial regression analyses.
b
P-value <0.05 from the univariate multinomial regression analyses. BMI = body mass index. IQR = interquartile range. NRS = Numeric Rating Scale for pain. PCI = Pain Coping Inventory. ROM = range of motion. SD = standard deviation. TKA = total knee arthroplasty. WOMAC = Western Ontario and McMaster Universities Osteoarthritis Index.