Table 2.
Baseline Characteristics for Each Trajectory Group
| n | Overall Sample | No/Rare LBP | Low Frequency-Stable LBP | Low Frequency-Increasing LBP | Moderate Frequency-LBP | High Frequency-Stable LBP | |
|---|---|---|---|---|---|---|---|
| (N = 5 976) | (N = 2 442) | (N = 1 040) | (N = 719) | (N = 745) | (N = 1 030) | ||
| Age | 5 976 | 74.14 ± 5.88 | 74.06 ± 5.99 | 74.52 ± 5.62 | 74.20 ± 5.93 | 73.72 ± 5.75 | 74.23 ± 5.90 |
| White race | 5 976 | 5 346 (89.46) | 2 167 (88.74) | 908 (87.31) | 655 (91.10) | 679 (91.14) | 937 (90.97) |
| Body mass index | 5 969 | 27.38 ± 3.83 | 27.06 ± 3.69 | 27.15 ± 3.67 | 27.75 ± 3.96 | 27.56 ± 3.91 | 28.00 ± 4.08 |
| Education (high school+) | 5 976 | 5 585 (93.46) | 2 304 (94.35) | 981 (94.33) | 670 (93.18) | 684 (91.81) | 946 (91.84) |
| Depressive symptoms | 5 975 | 296 (4.95) | 102 (4.18) | 61 (5.87) | 37 (5.15) | 39 (5.23) | 57 (5.53) |
| Greater/equal to 1 alcoholic drink per week | 5 968 | 3 113 (52.16) | 1 298 (53.24) | 547 (52.60) | 398 (55.51) | 384 (51.61) | 486 (47.23) |
| Current smoker | 5 975 | 206 (3.45) | 74 (3.03) | 39 (3.75) | 23 (3.20) | 31 (4.16) | 39 (3.79) |
| Lives alone | 5 976 | 835 (13.97) | 318 (13.02) | 149 (14.33) | 113 (15.72) | 108 (14.50) | 147 (14.27) |
| Married | 5 976 | 4 918 (82.30) | 2 038 (83.46) | 853 (82.02) | 573 (79.69) | 616 (82.68) | 838 (81.36) |
| Arthritis (body) or gout | 5 976 | 2 834 (47.42) | 906 (37.10) | 454 (43.65) | 374 (52.02) | 408 (54.77) | 692 (67.18) |
| Arthritis (low back) | 5 976 | 970 (16.23) | 140 (5.73) | 137 (13.17) | 118 (16.41) | 148 (19.87) | 427 (41.46) |
| COPD | 5 976 | 637 (10.66) | 187 (7.66) | 121 (11.63) | 75 (10.43) | 92 (12.35) | 162 (15.73) |
| CVD (MI, stroke, or angina) | 5 976 | 1 626 (27.21) | 549 (22.48) | 278 (26.73) | 213 (29.62) | 230 (30.87) | 356 (34.56) |
| Diabetes | 5 976 | 651 (10.89) | 238 (9.75) | 117 (11.25) | 87 (12.10) | 81 (10.87) | 128 (12.43) |
| Cancer (nonskin) | 5 976 | 1 088 (18.21) | 426 (17.44) | 200 (19.23) | 130 (18.08) | 130 (17.45) | 202 (19.61) |
| Fall in last 12 months | 5 976 | 1 262 (21.12) | 403 (16.50) | 240 (23.08) | 153 (21.28) | 179 (24.03) | 287 (27.86) |
| Fracture since age 50 | 5 976 | 98 (1.64) | 35 (1.43) | 13 (1.25) | 15 (2.09) | 15 (2.01) | 20 (1.94) |
| Antidepressant use | 5 635 | 351 (6.23) | 86 (3.76) | 56 (5.79) | 57 (8.28) | 57 (8.05) | 95 (9.68) |
| Benzodiazepine use | 5 740 | 205 (3.57) | 58 (2.48) | 30 (3.04) | 30 (4.30) | 23 (3.20) | 64 (6.42) |
| Opioid use | 5 740 | 158 (2.75) | 21 (0.90) | 16 (1.62) | 13 (1.87) | 25 (3.48) | 83 (8.32) |
| NSAID use | 5 740 | 888 (15.47) | 224 (9.57) | 133 (13.48) | 118 (16.93) | 133 (18.52) | 280 (28.08) |
| ADL limitation | 5 976 | 830 (13.89) | 185 (7.58) | 120 (11.54) | 110 (15.30) | 129 (17.32) | 286 (27.77) |
| IADL limitation (y/n) | 5 976 | 845 (14.14) | 186 (7.62) | 116 (11.15) | 107 (14.88) | 138 (18.52) | 298 (28.93) |
| Narrow walk-in m/s using best time | 5 421 | 1.15 ± 0.27 | 1.16 ± 0.26 | 1.15 ± 0.26 | 1.15 ± 0.28 | 1.14 ± 0.27 | 1.10 ± 0.27 |
| Walk speed in m/s using both times | 5 964 | 1.20 ± 0.23 | 1.22 ± 0.22 | 1.21 ± 0.22 | 1.20 ± 0.22 | 1.20 ± 0.23 | 1.15 ± 0.24 |
| PASE Score | 5 973 | 146.50 ± 68.16 | 150.30 ± 69.58 | 145.04 ± 65.23 | 144.80 ± 69.06 | 146.53 ± 68.82 | 140.10 ± 66.03 |
| Max of L/R grip strength, KG | 5 862 | 41.63 ± 8.50 | 41.72 ± 8.33 | 41.54 ± 8.47 | 41.72 ± 8.57 | 41.50 ± 8.69 | 41.57 ± 8.75 |
| Chair stands per 10 s (those unable/refused = 0) | 5 953 | 4.73 ± 1.52 | 4.91 ± 1.47 | 4.72 ± 1.51 | 4.71 ± 1.44 | 4.63 ± 1.54 | 4.39 ± 1.61 |
| Nottingham maximum power, both legs, watts | 5 426 | 208.46 ± 63.08 | 209.58 ± 62.97 | 206.39 ± 64.36 | 212.93 ± 61.96 | 209.35 ± 63.45 | 203.83 ± 62.26 |
| Total number of meds: (0, 1–3 or 4+) | 672 (11.93) | 344 (15.02) | 125 (12.91) | 73 (10.61) | 74 (10.45) | 56 (5.71) | |
| 5 635 | 2 164 (38.40) | 985 (43.01) | 373 (38.53) | 230 (33.43) | 257 (36.30) | 319 (32.52) | |
| 2 799 (49.67) | 961 (41.97) | 470 (48.55) | 385 (55.96) | 377 (53.25) | 606 (61.77) | ||
| Cognitive impairment trails B (>1.5 SD above mean) | 5 835 | 541 (9.27) | 215 (9.01) | 84 (8.29) | 66 (9.36) | 75 (10.29) | 101 (10.07) |
| Cognitive impairment, Teng 100 (<80) | 5 972 | 167 (2.80) | 66 (2.70) | 33 (3.17) | 12 (1.67) | 26 (3.49) | 30 (2.92) |
| SF-12 modified mental sum scale (median split) | 5 973 | 2 985 (49.97) | 1 079 (44.22) | 556 (53.51) | 386 (53.69) | 388 (52.08) | 576 (55.92) |
| SF-12 modified physical sum scale (median split) | 5 973 | 2 976 (49.82) | 864 (35.41) | 502 (48.32) | 377 (52.43) | 466 (62.55) | 767 (74.47) |
Notes: ALD = activities of daily living; IADL = instrumental activities of daily living; COPD = chronic obstructive pulmonary disease; CVD = cardiovascular disease; LBP = low back pain; NSAID = non-steroidal anti-inflammatory.